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Protein 101: The Complete Guide

by | Sep 22, 2020 | Last updated Oct 24, 2022

healthy vegetables and nuts

There are all kinds of macronutrients, micronutrients, vitamins and minerals that we need in our diets and protein is among the ones we need most. Besides being essential for muscle growth, it’s also a source of energy. The Merriam-Webster Online Dictionary describes protein as:

Some of the numerous naturally-occurring, highly-complex substances composed of amino acid residues joined by peptide bonds, containing elements such as oxygen, carbon, hydrogen, usually sulfur, nitrogen and sometimes other components (such as iron or phosphorus) and containing several important biological compounds (such as antibodies, enzymes, or hormones).

What is Protein? – A Quick Overview

Protein is a macronutrient found in some foods. It is vital to our survival. Oxygen, carbon, nitrogen, and hydrogen combine to produce chains of amino acids that are the building blocks of proteins.

There are a total of 22 amino acids, eight essential and 14 non-essential. The eight essential amino acids are tryptophan, lysine, leucine, threonine, valine, isoleucine, methionine, and phenylalanine. Non-essential amino acids include glycine, alanine, l-arginine, proline, asparagine, cysteine, aspartic acid, glutathione, taurine, glutamine, and serine.

Protein is important for organ health, hormone production, energy, endurance, immune function, and more. They carry nutrients in and out of cells. Protein isn’t just something you’re eating because you want to lose weight or build more muscle. You need to eat enough protein to achieve and maintain overall health.

Each cell of the human body contains protein from the skin to hair and nails. The most popular protein in your bones and ligaments is collagen. Without these structural proteins, you may not walk, stand, or move at all.

Protein is used for a variety of purposes by the human body, including cell regeneration, development of the brain, and growth of the hair and skin. The most well-known feature; however, is the impact of protein intake on muscle growth. 

Protein is one of three macronutrients, the other two being fats and carbohydrates. The human body can store fats and carbohydrates, but it doesn’t store extra protein. This means we need to make sure that every day we get enough to support body processes. The U.S. government sets the recommended dietary allowance (RDA) for minerals, protein, vitamins, fiber, fats, and carbohydrates. The RDA for protein starts at a low of about 0.8 grams per kilogram of body weight for sedentary adults 18 years and older, or about 0.36 grams per pound of body weight.

When using Noom to lose weight, you don’t have to worry about tracking protein intake. Foods are grouped into categories based on calorie density, so you learn how to eat more food and lose weight at the same time.

All About Amino Acids

The body relies on 20 total amino acids to carry out numerous functions. They are divided into essential and non-essential amino acids. Essential amino acids cannot be made by the body and have to be included in someone’s diet. In contrast, nonessential amino acids can be made by the body. While they are commonly found in people’s diets, they can be made from other amino acids. All amino acids are required to meet the body’s protein needs. These amino acids include:

Essential Amino Acids

  • Valine: Valine is one of three amino acids that has a branched side chain. This means it has a chain branching off of its molecular structure. Valine plays an important role in the body’s energy production, muscle growth processes, and regeneration processes following an injury.
  • Tryptophan: Even though tryptophan is commonly associated with Thanksgiving turkey comas, this molecule has other functions as well. It helps the body keep its nitrogen in balance, serves as a precursor to serotonin (which makes people feel happy), and also regulates sleep, appetite, and mood.
  • Threonine: Threonine is a major player in numerous proteins throughout the body including elastin and collagen. Threonine also plays a role in the body’s immune system and fat metabolism.
  • Phenylalanine: Phenylalanine serves as the foundation of numerous important neurotransmitters including dopamine and tyrosine. In addition, phenylalanine serves as the foundation of epinephrine and norepinephrine. Phenylalanine can also be converted into other amino acids.
  • Methionine: Methionine is a key player in countless detoxification and metabolism reactions throughout the body. It also regulates the absorption of minerals such as selenium and zinc. In this manner, methionine plays a key role in the growth of numerous tissues throughout the body.
  • Leucine: Leucine is another branched-chain amino acid. It plays a major role in blood sugar levels, wound healing, protein synthesis, and the repair of muscle tissues. In addition, Leucine regulates the body’s production of growth hormones.
  • Lysine: Lysine plays key roles in the production of energy, the regulation of the immune system, and the production of two key proteins, collagen and elastin. Lysine is also involved in the absorption of calcium, the production of hormones, and the regulation of enzymes.
  • Isoleucine: Isoleucine is another branched-chain amino acid. It plays a role in muscle metabolism and is concentrated in the body’s muscle fibers. In addition, Isoleucine plays a role in the regulation of the body’s energy levels, immune system, and the production of hemoglobin, which carries oxygen in red blood cells.
  • Histidine: Histidine forms the foundation of histamine, which is a neurotransmitter that plays a role in sleep, digestion, and the response of the immune system to foreign invaders. This amino acid also protects the nerve cells that maintain the myelin sheaths that protect them.

Non-Essential Amino Acids

  • Tyrosine: Tyrosine plays a key role in numerous chronic medical conditions by helping to control the body’s blood pressure, regulating the body’s mood, and helping people cope with chronic pain.
  • Serine: Serine plays an important role in the chemistry of the brain. It aids in the formation of numerous brain proteins in addition to regulating the synthesis of proteins in the immune system. Serine also works with muscle growth.
  • Proline: Proline is one of the most important amino acids for cell to cell signaling. Proline regulates the transmission of neurotransmitters that provide instructions to cells, enzymes, and other proteins that are located in other cells.
  • Glycine: Glycine is found in the skin and plays a role in wound healing. Glycine is a neurotransmitter that directs other cells and proteins to repair breaks in the skin. If the body has high levels of glycine, this could also cause fatigue.
  • Glutamine: Glutamine plays a role in nearly every cell. While this amino acid is concentrated in the brain, it also holds a key function in the formation of RNA and DNA. In this manner, Glutamine has an important role in DNA copying, transcription, translation, and proofreading.
  • Glutamic Acid: Glutamic acid forms the foundation of numerous protein synthesis reactions. In addition, Glutamic acid is the most common neurotransmitter in the central nervous system. Glutamic acid is used to transmit signals to other nerves throughout the body, controlling motor and sensory functions.
  • Cysteine: Cysteine is an amino acid that is commonly found in nails, skin, and hair. This amino acid forms the foundation of proteins that give these tissues their shape. In addition, Cysteine also plays a key role as a free radical scavenger and helps in the removal of key toxins from the body.
  • Aspartic Acid: Aspartic acid helps the body increase its stamina and plays a role in the removal of several toxins from the body, including ammonia. In addition, Aspartic acid helps in the synthesis of key proteins in the immune system.
  • Asparagine: Asparagine works in the central nervous system and mood regulation. It is derived from Aspartic acid and plays a role in numerous glycoproteins. Asparagine also works with removing ammonia from the body.
  • Arginine: Arginine helps the body regulate its blood pressure. It helps blood vessels relax, preventing hypertension. Arginine also helps men get and maintain erections. In addition, Arginine also works with the elimination of ammonia from the body, a common toxin and byproduct of numerous cellular reactions.
  • Alanine: Alanine is a detoxifier. It removes toxic substances from the body that might be released from the breakdown of key bodily tissues, such as muscle proteins and fibers that might be broken during exercise. High levels of alanine in the body could lead to chronic fatigue.

All amino acids are required for the human body to function properly.

Now that we know a little about what protein is and the amino acids that make them up, let’s take a closer look at what it does in the body. 

What Do Our Bodies Use Protein For?

Protein is vital for our body to function correctly. It’s required for growth, maintenance, biochemical reactions, structure, pH balance, and more. Here we dig deeper into many of the functions of protein in the human body. 

Growth and Maintenance

Protein plays a critical role in building and maintaining tissue. During times of growth (like infancy and childhood), pregnancy, and injury recovery, the body needs more protein than at any other time. While our bodies can naturally extract amino acids from old proteins, rarely does this system work well enough to provide all the protein and amino acids the body needs. This is why dietary protein intake is important for physical body maintenance, among other processes. 

Causes Biochemical Reactions

Enzymes are proteins that support thousands of biochemical reactions in and out of your cells. The enzyme structure enables them to combine with other protein molecules inside the cell, known as substrates that catalyze reactions that are important to your metabolism. Enzymes, such as sucrose and lactase, which help digest sugar, may also function outside the cell. For a reaction, other enzymes require specific protein molecules, such as vitamins or minerals. 

Enzyme-dependent body functions include:

  • Energy production
  • Muscle contraction
  • Blood clotting
  • Digestion

The failure or inadequate function of these enzymes can lead to disease. Enzymes are proteins that facilitate key chemical reactions in your body.

Acts as a Messenger

Hormones are proteins that serve to help communication between your organs, cells, and tissues. There are three major groups of hormones:

  • Steroids: made of fatty cholesterol. Sex hormones, testosterone and estrogen, are based on steroids.
  • Protein and peptides: made from a few to several hundred amino acid chains.
  • Amines: made of tryptophan or tyrosine amino acids, which help generate hormones related to sleep and metabolism.

Amino acid chains of different lengths bind proteins and peptides that contain various hormones and transfer information about your organs, cells, and tissues.

Provides Structure

Some proteins are fibrous and give rigidity and stiffness to cells and tissues. Keratin, elastin, and collagen are proteins that form a connective structure in the body. Keratin is a structural protein present in your skin, nails, and hair. Collagen is the body’s most abundant protein. It is the structural protein for tendons, muscles, ligaments, and skin.

Elastin is more versatile than collagen. Its excellent elasticity enables many tissues in your body, such as your lungs, arteries, and uterus, to return to their original form after they have stretched or contracted. A class of proteins known as fibrous proteins provides structure, strength, and elasticity to various parts of the body.

Balancing pH

Protein plays an essential part in the balance of acids and bases with blood and other body fluids. The equilibrium between acids and bases is measured by pH. Several buffer systems can preserve normal pH levels for your body fluids. A constant pH is necessary because even a minor change can be harmful or potentially fatal. Proteins are one way the body controls pH. One example is hemoglobin, a red blood cell protein. Hemoglobin binds small quantities of acid and helps preserve the blood’s regular pH value. Bicarbonate and phosphate are other examples of buffer structures in the body.

Balances Fluids

Proteins control body functions to maintain the balance of fluid. Globulin and albumin are blood proteins that help preserve the body’s fluid balance by attracting and retaining water. If you don’t eat adequate protein, your globulin and albumin levels will gradually decrease.

Therefore, blood can no longer hold these proteins in your blood vessels, and the fluid is pushed into the space between your cells. As fluid keeps increasing between cells, edema or swelling occurs, particularly in the stomach region. This can eventually lead to a type of severe protein malnutrition known as kwashiorkor, which mostly develops if a person consumes sufficient calories but does not eat enough protein.

Bolsters Immune Health

Protein helps to form antibodies or immunoglobulins to fight infections. Antibodies are blood proteins that protect the body from dangerous intruders such as bacteria and viruses. Once these foreign invaders come into your cells, the body develops antibodies to kill them.

Bacteria and viruses are free to multiply and to infect the body with the disease they cause without these antibodies. Your cells never forget how to create them, after your body has developed antibodies against a specific bacteria or virus. This helps antibodies to react quickly when a particular agent of disease invades. 

Stores and Transports Nutrients

Proteins transport substances in the bloodstream — to cells, tissues, and organs. Nutrients such as minerals or vitamins, blood sugar, oxygen, and cholesterol are transmitted via these proteins. For example, hemoglobin is a protein that brings oxygen from the lungs to tissues in the body. Transporters of Glucose (GLUT) transfer glucose into the cells while lipoproteins carry cholesterol and other fats. Protein conveyors are common, indicating that only certain substances are binding. In other words, cholesterol would not be transferred by a protein transporter that carries glucose. Proteins have storage functions as well. Ferritin is a protein contained in iron. Casein, the key protein in the milk that helps babies develop, is a storage protein. Some proteins transport nutrients all over the body, while others store them.

Benefits Of Dietary Protein

The amount of protein consumed, the nature or source of protein consumed, and the timescale of protein consumption all day long help assess the health benefits of dietary protein. Research demonstrates that dietary protein consumption over dietary requirements may have health benefits for some over the entire lifecycle. The following are benefits of dietary protein:

Reduces hunger levels and appetite.

The three macronutrients, carbs, fats, and protein, have various effects on your body. Studies have shown that protein is by far the most refined and makes you feel full. This is because protein reduces levels of your hunger hormone ghrelin. It also increases peptide YY levels, a hormone that makes you feel full. Such effects can be effective in suppressing appetite. In one study, raising protein intake from 15% to 30% of calories results in overweight men consuming 441 calories less per day without purposely limiting anything. When you need to lose weight and fat, try substituting protein for some of your carbohydrates and fats. This can be simple as to add a few extra bites of meat or fish in place of your rice or potato.

Noom can teach you how to fight hunger using your mind and body so you lose weight once and for all. Check out this clinically-proven weight-loss app today!

Increases muscle strength and mass.

A review of research shared in the journal Nutrients, summarizes the power of protein in terms of muscle strength and mass. Based on the 2019 review, “Increased protein intake contributes to greater strength and muscle mass gains when coupled with resistance exercise, allows for greater muscle mass preservation when consumed during periods of negative energy balance, limits age-related muscle loss, and, to a lesser extent, provides a greater muscle protein synthetic response when evenly distributed across meals.”

Good for your bones.

People who eat more protein tend to have improved bone health as they get older and are at a slightly lower risk of osteoporosis and fractures. Several long-term studies indicate a significant benefit to bone health for protein, like animal protein. Research also states that, to get the most out of dietary protein, in regards to bone health, adequate calcium levels are required. 

Increases fat burning and boosts metabolism.

High protein intake, both chronic and acute, will dramatically improve your metabolism, helping you burn more calories every day. Eating will enhance your metabolism. That’s how the body digests and utilizes nutrients in foods with calories. It is known as the thermal effect of food (TEF). Basically, research suggests “during weight loss, thermogenesis and protein use appear to be influenced by chronic protein intake, while appetite and ghrelin are more responsive to acute protein intake.”

Lowers your blood pressure.

In men and women between the ages of 30 and 54, “higher protein intakes were associated with lower mean [systolic blood pressure] and [diastolic blood pressure]. Both animal and plant proteins lowered BP and led to statistically significant reductions in [high blood pressure] risk.”

Helps maintain weight loss.

To many people, managing weight loss is a much more significant challenge than weight loss itself. A small improvement in the consumption of protein can help control weight. Based on research, replacing fat in your diet with protein helped participants lose and maintain weight

How Much Protein Do I Need?

Every day we must eat enough protein to meet the needs of our body. Protein helps the body maintain the correct amount of energy, carries nutrients, constructs and restores tissues, and provides other important functions. Do you know the amount of protein you need? We all need a different quantity, and various factors affect your number.

Determining Protein Needs

You may define a percentage of overall daily calories for your protein needs or achieve a certain number of grams of protein per day. You can also use your weight, activity level, and lean body mass. Current USDA dietary recommendations recommend that adult men eat 10 to 35% of their total calories from protein. 

You will eat about the same number of calories you lose each day to maintain a healthy weight. When you know the number of calories you eat, multiply by 10% and 35% to find your target range. For example, men who consume 2,000 calories daily need to take 200 to 700 calories from protein. 

Based on activity and weight.

An average person needs to consume at least 0.9 grams per kilogram of protein per day. One kg is equivalent to 2.2 pounds, which will require around 68 grams of protein a day for anyone weighing 165 pounds or 75 kg.

However, if you are very active, your protein needs can increase. Endurance athletes (they participate in sports such as cycling, running, or daily swimming) should consume 1.3 to 1.5 grams of protein per kilogram of body weight per day, or up to 113 grams of protein daily per 165 pounds.

Based on lean body mass.

The alternative way of assessing the amount of protein your body requires considers activity level and lean body mass. Some researchers claim this is a more accurate approach because our lean body mass needs more protein than fatty tissue.

Lean body weight (LBM) is bodyweight, which is not fat. Bone, organs, water, muscles, and other tissues are included. 

You can calculate your lean body mass using a mathematical equation that reads:

Men: (Weight in kg X 0.32810) + (Height in cm X 0.33929) – 29.5336

Women: (Weight in kg X 0.29569) + (Height in cm X 0.41813) – 43.2933

One pound is equivalent to 0.453592 kg and one inch is equivalent to 2.54 cm. 

Multiply your lean body mass by 2.2 to calculate how much protein you need daily. Let’s take a look at an example. 

Someone who has 72 kg of lean body mass would need (72 X 2.2) about 160 grams of protein daily. 

Calculating protein needs based on lean body mass is most effective with weight-loss diets. If protein requirements were based solely on total body weight, the suggested intake would be high enough to cause further weight gain, in some individuals. Thus, lean body mass is the best option when calculating protein intake for weight loss.

Do Athletes Need More Protein?

Athletes require more protein as both muscle and connective tissue construct and repair. According to EatRight.org, the average athlete needs between 1.2 and 2 grams of protein/kg body weight. It is suggested that athletes intake protein throughout the day, as opposed to one or two high-protein meals. What plays a role in how much protein athletes need and why does the need increase?


Muscle development occurs only by combining a healthy, protein-rich diet and exercise. Evidence has shown, for example, that the timing of protein intake plays a role. A high-quality protein (such as eggs, beef, fish, soy, or milk ) can increase muscle repair and development within the couple of hours after a workout – whether consumed alone or with carbohydrates. Duration and strength of the exercise are also considerations for protein requirements. Energy and protein needs depend on whether participants are in training or competing, seasoned participants, high-frequency intensity training, or engaging in new training programs.

Are supplements and powders required?

Many athletes can intake the required amount of protein without the use of supplements via food alone. Protein powders, protein shakes, and BCAAs can be beneficial if athletes need protein directly after training and don’t have time for a meal, however.

Do Men And Women Need The Same Amount Of Protein?

Research has shown that protein turnover rates are generally the same for men and women – though males do tend to need slightly more protein than females. However, there are instances and situations where one biological sex may need significantly more protein than another, such as during times of hormonal changes like puberty and growth spurts. Here are some details on how and when protein needs increase.


Between the ages of 10 and 12, girls and boys start undergoing body changes associated with puberty. These changes include development of muscle, increased height and weight, and bone growth. As puberty progresses and teens reach the ages of 14 to 18, protein needs increase from the standard 0.8 grams per kg of body weight to about 0.85 grams. The increase is small, but in some households, lack of access to proteins can play a role in overall development. Generally speaking, however, the average American teen gets twice the protein they typically need, so dietitians focus more on quality of macronutrients like protein versus quantity. 

Activity and Exercise

The real difference in protein requirements comes with athletics, exercise, and fitness. Female athletes need approximately 50% more protein than do their non-active male counterparts. On average, based on research using variable-intensity exercise like soccer, women need about 1.71 grams of protein per kg of body weight when athletically active. Non-active men, on the other hand, can get away with less than 1 gram per kg of body weight. 


The evident difference in protein needs between males and females comes during pregnancy and breastfeeding. Experts don’t necessarily suggest a specific grams/kg amount of protein during pregnancy, but the American Pregnancy Association does suggest a pregnant woman consume between 75 and 100 grams of protein daily. According to the association, “protein positively affects the growth of fetal tissue, including the brain. It also helps your breast and uterine tissue to grow during pregnancy, and it plays a role in increasing your blood supply.” Figuring as blood supply increases up to 60% by the last month of pregnancy, protein’s role is significant.


It is estimated that from age 50 onwards, the average person loses between 0.5% and 2% muscle mass. Muscle mass is also more difficult to grow as we age, but there’s good news. Consuming enough high-quality protein and exercising regularly, including weight-bearing exercises like lifting, help slow muscle loss. 

The recommended daily allowance, or RDA, for protein doesn’t yet reflect the increased need for protein as we age, claiming 0.8 grams of protein per kg of weight is enough. Research, on the other hand, shows that up to 1.2 grams of protein per kg of weight is more appropriate for men and women over the age of 65

Protein And Aging: A More Detailed Look

Muscle loss, or sarcopenia, is a natural process of aging. The resultant loss of muscle function and increased risk of falling, decreased capacity for everyday work and ultimately diminished quality of life are all factors to take into consideration when deciding on how much protein is right for your diet. A balanced and optimum protein-energy homeostasis is thus recognized as a significant dietary determinant of healthy aging. 

Optimal Level of Protein Intake During Aging

Based on research in the journal Nutrients, the aging could use more protein than the recommended daily guidelines. Researchers suggest up to 35% of total calorie intake from protein in elderly populations.

Counteracting Aging With Protein

According to a 2018 issue of Aging and Disease, “Muscular strength represents an independent role in the prevention of chronic diseases, whereas muscular weakness is strongly related to functional limitations and physical disability. Furthermore, low muscular strength has been recognized as an emerging risk factor for premature mortality beyond traditional risk factors such as hypercholesterolemia, obesity, hypertension, and smoking. For the above reasons and because muscle strength is known to decline with age, resistance-type and endurance-type exercise are currently prescribed by numerous health organizations in order to improve fitness and to counteract the adverse effects of aging on health-related parameters, including the risk of morbidity and mortality. In addition, the use of dietary protein supplementation can further augment protein anabolism, but can also contribute to a more active lifestyle, thereby supporting well-being and active aging in the older population.”

Protein Intake and Muscle Function

Another study, this time published in Current Opinions in Clinical Nutrition and Metabolic Care, “Recent evidence suggests that the RDA for protein is inadequate and that the timing and distribution of protein consumption throughout daily meals may be as important as the total quantity. Research has continued to advance our understanding of protein’s effects on muscle metabolism; however, there remains a need for large, long-term, randomized clinical trials examining whether the positive effects of dietary protein on muscle metabolism seen in acute studies will translate over the long term into gains of muscle mass, function, and overall health of older adults.”

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How Much Protein Is Too Much?

With all this focus on getting enough protein in your diet, is there a possibility you could be getting too much? The RDA for protein depends on factors such as:

  • Gender
  • Age
  • Breastfeeding and pregnancy
  • Activity levels

This RDA is a suggested intake, but what is the upper limit?

Because there are so many different opinions on how much protein the body needs, pinpointing an exact number of grams that’s too much is impossible, but we do know that you CAN consume too much protein. Harvard Health explains the idea of too much protein perfectly. “As with most things in life, there can be too much of a good thing and if you eat too much protein, there may be a price to pay.

For example, people that eat very high protein diets have a higher risk of kidney stones. Also, a high protein diet that contains lots of red meat and higher amounts of saturated fat might lead to a higher risk of heart disease and colon cancer, while another high protein diet rich in plant-based proteins may not carry similar risks.” So, yes, you can get too much protein in your diet, but just how much is too much is up for debate. Harvard goes on to say that an upper limit could be tentatively set at 2 grams of protein per kg of body weight daily. So, no more than about 125 grams for a 140-pound individual. 

Side Effects Of Too Much Protein

How will you know if you are consuming too much protein? Some of the physical side effects of too much protein include:

  • Dehydration
  • Indigestion and intestinal discomfort
  • Unexplained exhaustion
  • Nausea
  • Headache
  • Diarrhea
  • Irritability
  • Increased risk of kidney stones
  • Increased risk of heart disease
  • Increased risk of colon cancer (associated with high intake of red meat)

When To See A Doctor

Once you start a high-protein diet, it is important to weigh the risks and determine whether it is appropriate. Speak to your doctor often before beginning a new diet, especially if you have any health conditions. Your doctor and dietician will help you weigh the benefits and drawbacks of a high-protein diet based on your requirements.

Overall, a healthy, balanced diet and an active lifestyle are important. Adopt your agenda to meet your goals in the best way to maintain your well-being, whether it is weight loss or muscle gain.

Types Of Protein

Proteins are macronutrients that help body tissue growth and maintenance. Amino acids are the primary protein building blocks and are categorized as essential or non-essential. Essential amino acids are derived from foods rich in protein such as legumes, beef, and poultry, whereas non-essential foods are naturally synthesized in your body. According to the Centers for Disease Control and Prevention, 10% to 25% of your daily calorie requirements will be derived from proteins. The following are common types of proteins in the body:

Hormonal Protein

Hormones are protein-based, endocrine cell-secreted chemicals. Hormones are typically transmitted through the blood and relay signals from one cell to another as chemical messengers. The growing hormone affects some of the body’s cells, known as target cells. Such cells have unique receptors, to which the hormone is connected to transmit the signals. Insulin, which is secreted by the pancreas to regulate blood sugar levels in your body, is an example of a hormone protein.

Enzymatic Protein

Enzyme proteins improve the cell’s metabolic processes, including liver function, blood clotting, stomach absorption, and glucose conversion. An example is digestive enzymes that can quickly convert food into simpler forms.

Structural Protein

Structural proteins, also known as fibrous proteins, are essential components of your body. Collagen, keratin, and elastin are among them. Collagen shapes the muscle, bone, skin tendon, and cartilage connection. Keratin is the main structural part of hair, tooth, nail, and skin.

Defensive Protein

Antibodies or immunoglobulin are a central component of the immune system that prevents illnesses. In white blood cells, antibodies are produced that attack viruses, bacteria, and other harmful microorganisms, making them inactive.

Storage Protein

Storage proteins primarily store mineral ions in your body, such as potassium. Iron, for instance, is an ion essential for hemoglobin production, the principal structural component of red blood cells. Ferritin, a processing protein, controls and protects the body from the negative effects of too much iron. The storage proteins ovalbumin and casein are proteins found in breastmilk and egg whites, which are essential in the development of embryos.

Transport Protein

Proteins carry essential materials to the cells. For example, hemoglobin carries oxygen from the lungs to body tissues. Serum albumin contains fats in the bloodstream, while myoglobin consumes hemoglobin oxygen and then releases it through the muscles. Calbindin is another transport protein that enables calcium to be absorbed from the intestinal walls.

Receptor Protein

Located on the outside of the cells, the receptor proteins regulate the substances, including water and nutrients, that enter and leave the cells. Many receptors activate enzymes, while others allow endocrine glands to release epinephrine and insulin to stabilize blood sugar.

Contractile Protein

Contractile proteins are also known as motor proteins, which control heart and muscle contractions’ strength and speed. Those are actin and myosin. Contractile proteins can cause heart problems if extreme contractions occur. 

What About Complete and Incomplete Proteins?

Complete Protein

Any food that contains the nine essential amino acids is considered a complete protein. Examples of complete proteins include fish, eggs, chicken, beef, pork, tofu, dairy, and others. While you can’t get complete proteins from any single plant, eating a range of high-protein plant-based foods can round out the amino acid profile of your diet to achieve complete status. 

Incomplete Proteins

Incomplete proteins don’t contain all nine essential amino acids. You can find incomplete proteins in both the animal and plant categories. Eating a mostly, or totally, plant-based diet requires eating a variety of incomplete proteins. For instance, you’ll need to eat legumes, nuts, seeds, and other plants to intake all nine essential amino acids. 

What Foods Are High In Protein?

If you’re looking to balance out protein-rich with healthy, you can find a vast list of foods that fall into this category. Let’s take a closer look at some of the best sources of complete and incomplete proteins available today. 


Whole eggs are one of the most balanced and nutritious foods. They are a good source of healthy fats, vitamins, minerals, antioxidants that protect your eyes and brain nutrients that you need. Whole eggs are rich in protein, but egg white is almost pure protein. 

Content of protein: 33% of calories. 

One large egg has 6 grams of protein and 78 calories.


Almonds are a common tree nut. They are rich in essential nutrients such as starch, manganese, vitamin E, and magnesium. 

Content of protein: 15% of calories. 

One serving of almonds (28 grams) has 6 grams of protein and 164 calories.

Chicken Breast

One of the more common protein-rich foods is chicken breast. Chicken breasts are simple to prepare and work well in a wide variety of recipes. 

Content of protein: 75% of calories. 

One skinless, roasted chicken breast contains 53 grams of protein and 284 calories.


Oats are among the most popular grains. These deliver a range of nutrients like fiber, manganese, magnesium, thiamine, and vitamin B1. 

Content of protein: 14% of calories. 

One cup of oats has 11 grams of protein and 307 calories.

Cottage Cheese

Cottage cheese is a milk-based food rich in protein. It contains phosphorus, vitamin B12, calcium, selenium, and riboflavin (vitamin B2). 

Content of protein: 69% of calories. 

One cup of 1 percent fat low-fat cottage cheese contains 28 grams of protein and 163 calories.

Greek Yogurt

Greek yogurt is a very thick type of yogurt, also known as strained yogurt. It mixes well with sweet and savory food. It has a smooth appearance and a high nutrient quality. 

Content of protein: 69% of calories. 

One 6-ounce serving has 17 grams of protein and just 100 calories. 


Milk provides nearly all the nutrients the body requires. This is a healthy protein source with a high content of phosphorus, calcium, and riboflavin (vitamin B2). If your fat intake is concerned, low or zero fat milk is an alternative. 

Content of protein: 21% of calories. 

One cup of whole milk contains 8 grams of protein and 149 calories.

One cup of soy milk contains 6.3 grams of protein and 105 calories.


Broccoli is a protein-rich plant that contains potassium, vitamin C, vitamin K, and fiber. It also provides bioactive nutrients that can protect against cancer. 

Content of protein: 33% of calories. 

One cup of chopped broccoli consists of 3 grams of protein and just 31 calories.

Lean Beef

Lean beef is rich in protein as well as vitamin B12, iron, and a significant number of other essential nutrients that are highly bioavailable. 

Content of protein: 53% of calories. 

One serving of lean sirloin steak (85 grams) contains 25 grams of protein and 186 calories.


Tuna is a common dietary fish. In a variety of baked dishes, you can eat it hot or in salads. Fat and calories are low, but the fish is a rich source of protein. Tuna are a good source of various nutrients and contain omega-3 fats. 

Content of protein: 84% of calories. 

One can contains 27 grams of protein and only 128 calories.


Quinoa is a common pseudo cereal, considered by many to be a superfood. The vitamins, minerals, antioxidants, and fiber are abundant.

Content of protein: 15% of calories. 

One cup of cooked quinoa contains 8 grams of protein and 222 calories.

Whey Protein

A protein supplement can be helpful if you’re pressed for time and unable to cook. Whey protein is a high-quality protein that can increase protein intake without adding extra fat and calories. This can even help you to lose weight. 

Content of protein: varies among brands. 

More than 90% of calories can be protein – at 20–50 grams of protein per serving, on average.


Lentils have a high content of potassium, manganese, iron, folate, magnesium, copper, and other nutrients. They are among the best sources of protein, and for vegetarians and vegans, they are an excellent alternative to meat. 

Content of protein: 31% of calories. 

One cup of boiled lentils contains 18 grams of protein and 230 calories.

Where do these foods fit into the green, yellow, red food categorization of Noom? Download the app today and take a look at just how accurate Noom tracking really is.

Types of Protein Powders

You can visit any online or offline vitamin shop and find an entire shelf loaded with protein powders. What makes each different and is one necessarily better than another? 


Whey is the liquid milk protein byproduct of cheese production. This is the most common type of protein supplement. Within the whey protein category there are three types of whey: concentrate, isolate and hydrolyzed. We’ll discuss these more later. 


Casein is also a byproduct of cheese production. Of the milk proteins extracted, 20% are whey and the remaining 80% are casein. The big difference between the two is that casein digests more slowly than whey. 


If you take the fat out of soybeans and grind the leftover flakes you’ll get soy protein. Almost all soy protein is low fat and zero cholesterol. 


If you were to score protein powders based on quality of amino acids, egg protein powder would come out on top. Because egg protein is animal-based, it is a source of complete protein. 


The above-mentioned proteins are the big four, but they are far from the only sources of protein powder. You can also find powders derived from rice, peas, hemp, seeds, chia, and quinoa, to name a few.

Can Protein Powder Help You Lose Weight?

Now that we know much more about protein and the best sources of the macronutrient, both in food and supplement form, let’s take a closer look at how protein powder, specifically, can impact weight loss. 

Dietary protein in weight management: a review proposing protein spread and change theories

This study aimed to propose two separate theories including the “protein spread theory” as well as the “protein charge theory” to explain discrepancies that might have shown up in the literature. Protein spread theory refers to the idea that there has to be a certain difference in protein intake between two groups in order to see body composition changes. The protein change theory states that for the higher protein group, this change from the baseline intake of the group to see body composition changes. The study showed that the most important factor in changing body composition involved increasing protein intake from the baseline of the individual. A modest increase in protein led to favorable body composition changes.

Whey Protein Supplementation Enhances Body Fat and Weight Loss in Women Long After Bariatric Surgery

This study was published in the journal of Obesity Surgery and followed the course of a randomized controlled trial to look at whey protein supplementation and its impact on the weight loss and body composition of participants who regained weight following bariatric surgery. There were 15 patients in the study. All of them underwent gastric bypass and they were randomized to different groups. One group received whey protein while the other did not. The study found that those who received whey protein supplementation actually lost more weight and body fat, indicating that whey supplementation can help with long-term weight management following gastric bypass surgery.

Protein supplements after weight loss do not improve weight maintenance compared with recommended dietary protein intake despite beneficial effects on appetite sensation and energy expenditure

The researchers took a look at the impact of protein supplementations on weight maintenance and weight loss compared to a control group. There were 151 total participants. The researchers found that protein supplementation did not result in increased weight management or improved biochemistry profiles after losing weight when compared to a group that had a normal intake of dietary protein, published in the American Journal of Clinical Nutrition.

Effect of Protein Supplementation During Diet-Induced Weight Loss on Muscle Mass and Strength

This study, published in the Journal of Obesity, took a look at the impact of high protein intake on weight loss and muscle mass. The researchers followed 70 people with obesity and randomized them into several different groups. One group was supposed to maintain their weight, one group received the daily recommended value of protein and was supposed to lose weight, and the third group was supposed to lose weight but also received protein supplementation. The researchers found that whey protein supplementation did not have a significant impact on muscle mass or strength in those who were trying to lose weight.

Effect of a Whey Protein Supplement on Preservation of Fat Free Mass in Overweight and Obese Individuals on an Energy Restricted Very Low Caloric Diet

The study aimed to take a look at the impact of whey protein supplements given before going to sleep on free fat mass. 29 individuals with obesity participated in a walking program. Half received whey protein supplementation while the other half did not. The study found that there were no significant differences between the groups, indicating that whey protein supplementation did not lead to any improvements in the quality of the weight loss in obese individuals.

Can Protein Powder Help You Build Muscle?

Whey is a by-product of the process of producing cheese – the liquid is left after the milk has strained and curdled. It is one of the world’s most common sports nutrition supplements in its powder form, due to its quality, cost, and performance. After you have eaten whey, the body absorbs it so that it enters your muscles and then your bloodstream very rapidly. Whey comes in three types, all abundant in BCAAs or branched-chain amino acids, the necessary elements for restoration and repair of the muscular damage done by exercise.

There have been numerous medical studies performed taking a look at muscle growth and protein. Some of the key studies performed include:

Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training

A study, published in the Journal of the International Society of Sports Nutrition, took a look at prior research regarding the effects of protein and weight training. The researchers found that pre and post-workout protein increases:

  • Muscle hypertrophy
  • Muscle strength
  • Physical performance
  • Lead body mass
  • Training session recovery

On the other hand, specific gains vary depending on the type of protein ingested and the amount. For example:

  • Fat-free milk after a workout can promote muscle strength and lean body mass while reducing fat.
  • Leucine leads to protein synthesis and muscle hypertrophy when three to four grams are ingested after a workout.
  • A fast-acting carbohydrate, such as glucose, can increase the effectiveness of protein supplementation.

The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults

This study tried to provide a comprehensive analysis of all literature that looked at protein and its potential role in accelerating gains in muscle mass and strength. The researchers found numerous studies looking at adults between 18 and 50 years of age that looked at protein supplements and their impacts on muscle mass, strength, and power.

The study found that consuming supplemental protein was unlikely to result in gains in individuals who did not have a lot of experience with resistance training (such as weightlifting). On the other hand, those who work out on a regular basis are likely to experience more significant muscle gains as a result of protein supplementation.

Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Performance Recovery after Resistance Exercise

A research piece published in the journal Nutrients took a look at changes in protein metabolism and exercise performance during the recovery process following a resistance workout, such as weight training. In the study, 12 men consumed either whey protein or a placebo the evening immediately after an intense workout. Then, the researchers conducted tests periodically during the next 24 hours to see how their protein metabolism changed. The researchers found that:

  • Net protein balance was improved in the whey protein supplement group.
  • There was less protein breakdown in the whey protein supplement group.
  • Those who took the whey protein supplement experienced improved muscle strength, peak power, and number of repetitions to failure when compared to the control group during the next workout.

Therefore, the researchers found that whey protein supplementation improves exercise performance and protein metabolism.

Effects of Protein Supplementation on Performance and Recovery in Resistance and Endurance Training

This study took a look at the evidence supporting the use of protein before and after workouts to increase protein synthesis. The researchers found that protein consumption during and after a workout enhances physical performance for the next workout by expediting the recovery process. The researchers also found that those who do not eat anything following a workout are at a particularly severe disadvantage during the recovery process.

The Effect of Whey Protein Supplementation on the Temporal Recovery of Muscle Function Following Resistance Training

The research, as published in the journal Nutrients, took a close look at whey protein as a nutritional supplement. The review looked at 13 separate randomized controlled trials and combined the results. They found that whey protein supplementation improved the recovery of the body’s muscle fibers in terms of total contractile function. This means that whey protein plays an important role in the recovery of the body’s muscles following a workout.

Protein Supplements and Their Relation with Nutrition, Microbiota Composition and Health

This study took a look at the role of protein supplements in athletes. The study found that high-protein diets can help people reduce weight; however, the origin of these proteins plays a role in athletic performance. For example, eating processed foods leads to the development of certain illnesses and diseases. The researchers make the point that athletes have more control over the quality of their proteins if they supplement their workouts with whole foods such as fish, eggs, and dairy products (along with fiber to maintain gut health) instead of relying on refined protein supplements.

Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit

Published in the journal Nutrients, this study highlighted a disparity between current daily protein recommendations from regulatory health organizations when compared to the latest literature. The research study highlights several manuscripts that provide evidence that higher levels of protein above the recommended daily allowance (RDA) can prevent the loss of lean body mass while also building muscle. Even though the evidence in support of increasing protein intake is clear, actual dietary patterns have not changed for the average American. Therefore, the researchers make the point that current protein intake recommendations need to be evaluated and adjusted, claiming that the protein intake recommendations should vary based on someone’s overall lifestyle.

Effects of whey protein supplementation prior to, and following, resistance exercise on body composition and training responses

A study was published in the Journal of Exercise Nutrition and Biochemistry and took a look at whether a protein blend supplement before and after resistance exercise could increase muscular function. The study lasted 12 weeks and divided participants into two groups. One group took protein supplements before and after workouts while the other did not. The researchers found that the group taking a protein supplement had a lower intake of protein overall; however, they performed better during workouts after 12 weeks. Therefore, the researchers came to the conclusion that the timing of protein supplements was more important than the amount of protein supplements overall. Athletes looking to get the most out of their exercise routines should take protein supplements before and after workouts.

Types of Whey Protein

Within the category of whey protein powder, there are three types defined based on the amount of protein, lactose, and fat per serving. 

Whey Protein Concentrate

Whey protein concentrate contains between 25% and 89% protein, 4% and 52% lactose, and 1% and 9% fat. Of all types of whey protein, concentrate is the least standardized, which makes it more difficult for the consumer to find consistent quality. 

Whey Protein Isolate

Isolate is much more standardized than whey protein concentrate. To be defined as isolate, the powder must contain between 90% and 95% protein, 0.5% and 1% lactose, and 0.5% and 1% fat. 

Hydrolyzed Whey Protein

The protein content for hydrolyzed whey is more consistent than concentrate at an average of 80% to 90% protein. The biggest difference is that hydrolyzation breaks down the protein into peptides which are easier for the digestive system to process.  

How Much Protein Powder To Build Muscle?

The current US RDA is between 0.7g and 1g of protein per pound of body weight (1.6g to 2.2g per kg). 

Online protein calculators take factors other than body weight into consideration. For instance, some ask the user to include height, weight, sex, and activity level to estimate total protein requirements. Let’s take a look at a few examples from the calculator on Bodybuilding.com


  • Age: 25
  • Height: 6’2”
  • Weight: 275 pounds
  • Goal: Build Muscle

Now, based on activity level, the total amount of suggested protein per day can vary. 

  • Lightly Active: 227g/day
  • Moderately Active: 262g/day
  • Very Active: 296g/day
  • Extra Active: 331g/day

Now, how about a woman who’s one foot shorter and 40 pounds lighter?


  • Age: 25
  • Height: 5’2”
  • Weight: 235 pounds
  • Goal: Build Muscle

What does the calculator say for the woman?

  • Lightly Active: 183g/day
  • Moderately Active: 209g/day
  • Very Active: 236g/day
  • Extra Active: 262g/day

We also find that different organizations offer different insights into how much protein a person should consume. For instance, that same 25-year old male, based on the American Dietetic Association (ADA), The Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO) all suggest different protein intake ranges. 

Light Exercise

  • ADA: 125g to 225g/day
  • CDC: 77g to 270g/day
  • WHO: at least 104g/day

Now, for all other activity levels the ADA and WHO stay the same, in regards to protein intake suggestions, but the CDC changes based on activity level with increased activity sparking increased protein needs. 

Plant-Based Protein vs. Animal Protein

Animal Protein

Twenty different amino acids are required in the human body. Our bodies produce 11 (non-essential amino acids), but the remaining nine must be obtained by diet (essential amino acids). Complete proteins are animal proteins, including milk, meat, and eggs, ensuring that they provide the essential amino acids that our body needs. 

On the other hand, several studies have linked red meat consumption with an increased risk of heart disease, stroke, and early death – though research resulting in the opposite is also available.

Research from 2017, as published in the International Journal of Preventive Medicine claims recent findings do not support the idea that eating red meat, as long as it’s consumed in moderation, increases cardiovascular risk factors.

Flip the script and you’ll find 2018 research that makes the opposite claim. This time around, research in the journal Hypertension shares, “Over a 4-year period, red meat consumption was related to cardiovascular target organ damage in hypertensive [adults]. These findings emphasize the importance of dietary measures for cardiovascular disease prevention.”

Plant Protein

Some plants can be healthy protein sources, often fewer calories, and less adverse effects than animal products. Some plant proteins are complete proteins, meaning that they contain all nine essential amino acids we need. Some other plants lack completeness and amino acids are lacking, so it is important to eat a variety of plant-based foods to get all nine.

Studies indicate that the risks of certain diseases like obesity, cancer, hypertension, type 2 diabetes, and ischemic cardiovascular disease are lower among people on vegetarian or vegan diets (often depending on plant protection).

Plant vs. Animal – Complete vs. Incomplete

One issue of the 2015 edition of the Journal of Nutrition found that plant proteins tend to be light on amino acids like methionine, lysine, and leucine. These are prevalent in animal proteins. However, the study authors suggest a few ways to even the odds. First, you can eat more plant-based foods to up the total protein and amino acid intake. Second, you can choose to pick fortified plant-based proteins. And third, you can consume a wide variety of protein sources to ensure optimal amino acid intake for anabolic muscle growth. 

Plant vs. Animal – Muscle Maintenance

According to research in the journal Nutrients, “High-quality protein consumption optimizes protein metabolism at both the whole-body and skeletal-muscle level, especially in older people. Plant-based protein sources that are rich in fiber and micronutrients may be valuable, but they have lower anabolic potential than animal-based proteins.” So, when it comes to maintaining muscle mass, at least some research shows animal proteins are more effective

Quick List of High-Protein Food Sources

We want you to come away today with all the information you need to make the best decision possible on healthy sources of protein. Feel free to copy this list and post it on the refrigerator so you know exactly how much protein is in some of your favorite foods.


  • Whitefish (1 fillet or 154g): 38g
  • Salmon (½ fillet or 198g): 40g
  • Chicken (1 cup or 140g): 38g
  • Turkey (1oz or 28g): 8g
  • Lean Beef (3oz or 85g): 22g
  • Pork (3oz or 85g): 29g
  • Shrimp (100g): 24g
  • Crab Meat (3oz or 85g): 16g
  • Eggs (1 large): 6g
  • Bison (4oz or 113g): 17g
  • Venison (3 oz or 85g): 26g


  • Greek Yogurt (170g): 17g
  • Cottage Cheese (1 cup or 225g): 25g
  • Milk: (1 cup or 240ml): 8g


  • Black Beans (1 cup or 172g): 15g
  • Tofu (½ cup or 124g): 10g
  • Tempeh (1 cup or 166g): 31g
  • Seitan (3.5 oz or 100g): 25g
  • Nuts and Seeds (1 oz or 28g): 6g
  • Almond Milk (1 cup or 240ml): 1g
  • Oat Milk (1 cup or 240ml): 3g
  • Soy Milk (1 cup or 240ml): 7g
  • Corn (1 cup or 164g): 5g
  • Potato (1 medium or 148g): 3g
  • Broccoli (1 cup or 91g): 6g
  • Oats (1 cup cooked or 234g): 6g
  • Nutritional Yeast (1 oz or 28g): 14g
  • Green Peas (1 cup or 240ml): 9g
  • Wild Rice (1 cup or 240ml): 7g

According to Healthline, “Vegetables with the most protein include broccoli, spinach, asparagus, artichokes, potatoes, sweet potatoes and Brussels sprouts. They contain about 4–5 grams of protein per cooked cup.”

The website goes on to say, “Fresh fruits generally have a lower protein content than vegetables. Those containing the most include guava, cherimoyas, mulberries, blackberries, nectarines and bananas, which have about 2–4 grams of protein per cup.”

Nearly all fruits and vegetables fall into the green zone on Noom. That means you can eat much more without feeling guilty and you’ll feel full in no time. Learn this trick and more with the Noom app.

What Have We Learned About Protein? 

Today, we’ve uncovered that protein is one of three main macronutrients found in food. The body uses protein for growth, maintenance, biochemical reactions, structure, pH balance, immune system function, and to transport nutrients, among many other functions.

We’ve also touched on the fact that proteins are made up of amino acids. There are 20 amino acids, nine essential, which we must get from food products and 11 non-essential that the body produces. 

What about protein and weight loss? There’s evidence that protein can help stave off hunger. It’s best to get protein from whole foods and natural sources, but protein powders will work when food sources aren’t available. 

As for protein and muscle growth – muscles need protein to grow. Though just how much protein is up for debate, the consensus is around 1g of protein per pound of body weight when aiming to increase muscle mass. 

There are various factors that affect how much protein we need each day, including sex, age, weight, and activity level. 

One thing is certain, the human body needs plenty of lean, nutrient-rich protein sources that cover a wide spectrum from animal proteins to plant proteins to seeds, grains and beyond. When it comes to this macronutrient, it’s all about quality. 

Questions and Answers

Q: What are the 3 types of proteins?
A: Protein is a macronutrient found in foods that’s made up of hydrogen, carbon, nitrogen, oxygen and chains of amino acids. There are three types of proteins: membrane, globular, and fibrous. 

Q: Where is protein found?
A: Protein is found in hair, nails, skin, organs, muscles, bone, and every other body part and tissue. 

Q: Are enzymes proteins?
A: Some, but not all, enzymes are proteins. Ribozymes are a part of RNA and are not made of proteins, but they are enzymes.

Q: What is whey protein?
A: Whey protein is what’s left after cheese is made from milk. The liquid is dehydrated to form protein powder.

Q: What protein is best?
A: The best sources of protein for weight loss are whey protein, casein protein, egg protein, and plant proteins. 

Q: How to make a protein shake?
A: To make a protein shake mix your protein powder with a non-carbonated beverage. Depending on the powder, you may have to process the shake in a blender to completely break down the powder.

Q: What are proteins made of?
A: Proteins are made of amino acids. Amino acids are organic compounds composed of things like sulfur, hydrogen, nitrogen, carbon, and oxygen. 

Q: How much protein should I eat for bulking?
A: It is recommended that you eat about 1g of protein per pound of body weight during a bulking phase. That equates to about 2g/kg. 

Q: What are the building blocks of protein?
A: Amino acids are the building blocks of protein. 

Q: What is protein synthesis?
A: Protein synthesis is a cellular process that replaces lost proteins with new proteins.