- Intermittent fasting can be safe and effective for weight loss, but it’s not for everyone.
- How much weight you can lose depends on factors like age, activity level, fasting plan, and current weight.
- Intermittent fasting can be challenging at first—prepare for emotional struggles by knowing your food triggers.
Maybe you’ve heard that intermittent fasting (cycling between fasting and eating periods) can help you lose weight without cutting calories—or that it gives your metabolism a boost.
If that sounds exciting, we get it. Losing weight by focusing on when (not what) you eat seems like an easy, doable strategy. But does intermittent fasting for weight loss work?
Intermittent fasting isn’t a magic bullet. You’ll still need to practice mindful eating while on an intermittent fasting weight loss plan, but it can help you get closer to your weight loss goals.
To learn more about intermittent fasting for weight loss (and to get answers to your most pressing questions), we chatted with Kendra Gutschow, RDN (registered dietitian nutritionist).
Note: Consult with your medical provider before making dietary changes.
Ready to make a lasting change?
A healthier you, wherever you are.
This is Chapter 3 of Noom's Guide to Intermittent Fasting:
Does intermittent fasting work for weight loss?
Intermittent fasting is thought to work by helping you eat fewer calories, which causes your body to tap into stored body fat for energy.
According to Gutschow, you lose weight when you eat within a calorie deficit, meaning you burn more calories than you eat. Because intermittent fasting limits when you can eat, it can lead to an overall reduction in calories.
For example, let’s say you eat nutritious meals throughout the day but tend to snack mindlessly at night. (We’ve all been there.)
If you stick to a 16-hour fasting period that begins at 8 p.m., you’ll probably avoid eating some of those extra calories when snacking.
In one study, participants who chose to fast for 10- to 12-hour windows averaged a 20% reduction in calories from intermittent fasting alone. The best part? They weren’t even trying.
Eating within a calorie deficit gives your body a chance to burn stored fat for fuel. Your body uses sugar from foods as a primary fuel source—but when that’s tapped out, it turns to stored fat for energy.
Is intermittent fasting safe for weight loss?
Gutschow doesn’t recommend this intermittent fasting if you:
- Have a history of blood sugar issues (including type-2 diabetes).
- Take medications affected by food.
- Have any history of eating disorders.
- Are pregnant or breastfeeding.
- Have any significant health conditions.
As always, it’s important to chat with your doctor before starting any weight loss plan.
To learn more about the potential health benefits and side effects of intermittent fasting (including a lower risk of heart disease, lower cholesterol, and lower blood pressure), check out our guide to intermittent fasting.
How much weight can you lose with intermittent fasting?
It depends on the person. If you look at stories shared online, you’ll find all kinds of different weight loss testimonials.
That’s because how much weight you lose when you change your habits (and how quickly) varies by person. Gutschow says that factors like age, activity level, fasting plan, and current weight have a big impact.
Case in point: Individuals with more weight to lose may drop pounds faster when starting a weight loss plan.
If you’re wondering how intermittent fasting stacks up against other weight loss methods, like daily calorie restriction, the research looks good. The results of one study suggest that intermittent fasting is likely just as effective as calorie restriction in helping people lose weight.
Another small study comparing calorie restriction and intermittent fasting showed similar short and long-term weight loss. After one year, participants were equally successful in keeping the weight off.
How to start intermittent fasting for weight loss: 6 tips for success
Ready to give intermittent fasting a try? We’ve put together strategies and tips to help you get the most out of your journey.
1. Choose a plan that fits your lifestyle
One of the major perks of intermittent fasting is how flexible it is—and research suggests one fasting pattern isn’t necessarily better than the other for weight loss.
The best intermittent fasting plan for weight loss is the one that works for your lifestyle. Gutschow advises experimenting to find one that feels doable long-term.
These are the most common types of intermittent fasting for weight loss:
- 16/8: This simple schedule requires eating within an eight-hour window and fasting for the remaining 16 hours of the day.
- 5:2: Eat as you usually would for five days out of the week. On the other two days, eat 25% of your daily calorie needs.
- Skipping breakfast: This less formal approach involves only eating lunch and dinner.
Think about your current habits and build your plan around them. For example, the 16/8 method could be a good fit if you usually skip a meal. Or, if you prefer to avoid long fasting windows, you might try starting with the 5:2 method.
There are also some more extreme forms of intermittent fasting:
- Eat-stop-eat: For five to six days per week, eat normally. On the remaining one to two nonconsecutive days, this plan requires a 24-hour fast.
- Alternate-day fasting: One to two nonconsecutive 24-hour fasts, with normal eating during non-fasting days.
- Warrior diet: Eat sparingly during the day, followed by a single large meal at night. This plan suggests eating 80% to 90% of your calories during a four-hour eating window.
Gutschow notes that restricting food for 24 hours and beyond may slow down your metabolism and cause your body to hold onto excess calories—not exactly the desired effect.
These fasts can also be difficult (especially for newbies), and Gutschow does not recommend them.
2. Understand the emotional side of fasting
If you’re like most people, you’ll probably start your intermittent fasting journey feeling determined and empowered. It’s exciting to know you’re taking steps to get closer to your goals.
But it’s important to prepare yourself for the emotional side of fasting, too. Gutschow acknowledges that people may feel hungrier at first—and feeling hungry is just as much an emotional struggle as a physical one.
Thankfully, Gutschow reassures us that this “extra hungry” feeling usually fades within a few weeks. Be sure to check with your doctor if this feeling continues or if you have any concerns.
When you notice yourself feeling more hungry (and maybe more frustrated) than usual, take a look around. Do you notice that certain social situations trigger this feeling? Is it more challenging to fast when your favorite treats are sitting on the counter?
By putting on your detective hat and understanding what your triggers are, you can take steps to avoid them during your fasting window.
3. Experiment with new foods to stay motivated
Once you’ve been on an intermittent fasting plan for a while, try shaking up your routine by experimenting with new foods.
Stepping outside your comfort zone is a fun way to build nutritious habits into your fasting plan, like adding more vegetables to your dinner plate.
Small shifts will help you find creative ways to boost your vitamin and nutrient intake—and you can impress your friends with some fun options at the next dinner party.
If a fun-looking fruit or vegetable catches your eye at the farmer’s market, try it out! Look into uncommon produce—like Peruvian purple potatoes or Jamaican ugli fruit—and add it to your next meal. You can thank us later.
Not sure how to map out your meals? Check out our sample meal plans for more inspiration!
4. Aim for moderation in your food choices
First things first: you can throw out the rulebook on “good” and “bad” foods (insert sigh of relief). All foods can be eaten without guilt or shame in moderation.
Instead, try thinking about food in terms of calorie density. Calorie density refers to the total calories in a specific volume of food.
Treats like soda and chips have a high-calorie density, while fresh fruits and vegetables have a lower density. Foods with lower calorie densities also tend to have a higher water content, which helps keep you hydrated and feeling full.
Gutschow says foods like complex carbohydrates (think vegetables and fruits), healthy fats, and lean proteins fill you up with fewer calories and leave you feeling nourished and satisfied for longer.
Knowing which foods keep you feeling satisfied with fewer calories helps you make choices that move you closer to your weight loss goals.
Our suggestion? Aim to eat mostly low-calorie density foods while still allowing room for your favorite treats.
5. Right before your fast, eat whole grains, fiber, and protein
Before your fast, Gutschow recommends eating a meal that includes a combo of whole grains, higher-fiber carbs, and protein.
This formula is key for slowing down digestion and providing satiety and energy for a long time. It’s the perfect way to finish up your eating window, and you’ll be less likely to have an energy crash or feel early hunger pangs mid-fast.
6. Log your meals
By now, you know you need to be in a calorie deficit to lose weight—and intermittent fasting seems to make that easier.
But how do you know for sure if you’re in a calorie deficit? By tracking what you eat.
You can start by using a calculator tool (like our calorie deficit calculator) to figure out how many calories to eat in a day.
Noom Weight can help you keep an eye on your calorie intake with food logging. And logging your food isn’t just about calories—it gives you a visual breakdown of your food choices and can highlight areas where you might want to make changes.
If you notice that you keep breaking your fast early in the day, for example, you can adjust your eating window to start earlier.
Ready to make a lasting change?
A healthier you, wherever you are.
3 common intermittent fasting challenges (with solutions)
If you find yourself putting in the work but getting minimal results, you may be hitting one of several common intermittent fasting speed bumps.
Let’s explore what they are and how to navigate them.
1. Overeating during your non-fasting window
If you’re feeling extra hungry after a fast, it’s oh-so-tempting to scarf down whatever is nearby to curb your hunger. This can lead to overeating.
Gutschow suggests planning meals ahead of time to stay on track. Work in balanced choices throughout your day and keep healthy options on hand to fend off hunger pangs.
But remember: Going off course doesn’t mean you’ve failed. Life happens, and things won’t always go according to your plans.
If you forget to plan and break your fast with a tasty donut or treat, that’s okay! Your next meal is a chance to incorporate satisfying options that will help you feel fuller, longer.
2. Not eating enough nutritious foods
Not getting enough nutrients from your foods may leave you feeling physically and mentally tired. When you’re on an intermittent fasting plan, filling up on nourishing foods is essential. You need nutrients that will sustain you throughout the day.
A simple way to approach eating nutritious foods is by using the calorie density principle we mentioned earlier.
To put this principle into practice, take on the mindset of a curious scientist. Ask yourself what choices will give you the most bang for your buck when it comes to nutrition.
According to Gutschow, no treats are off limits—we all deserve them once in a while! But, when possible, try to limit processed foods with little nutritional value.
3. Forgetting to plan ahead for social situations
Social situations can be tricky, especially for intermittent fasting newbies. What happens if you get invited to dinner at your favorite restaurant, but the timing is outside of your eating window?
While breaking one fast won’t hurt, Gutschow says the best remedy is planning. If you know you’ll be out late with friends and family, plan to shift your fasting window that day. Start eating later in the day, so you don’t need to worry about timing while you’re out having fun.
You can also try switching to a different eating plan that week, like 5:2.
Reach your intermittent fasting weight loss goals with Noom
Getting started with intermittent fasting can be as straightforward as choosing an eating pattern and sticking to it.
For those who would prefer to ease in slowly, Gutschow suggests looking at when you typically finish dinner and planning to start your fasting hours around that time. Start small—try skipping breakfast and see how you feel, then work your way up to a fasting pattern like 16/8 or 5:2.
If you need extra support, learn about how Noom can help with intermittent fasting.