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Do Fat Burners Break a Fast? (The Science Behind it)

Isaac Robertson
Published by Isaac Robertson | Co-Founder & Chief Editor
Last updated: August 12, 2023

As long as your fat burner doesn't contain carbohydrates or proteins, it is okay to use it while intermittent fasting.

The trick is to select the right combination of ingredients that work best in this particular scenario.

You've probably heard people saying that intermittent fasting and fat burners can be a powerful fat loss combination, but knowing how both of them work individually is what will save you precious time and money, so that's why we're going to cover all the basics in this article.

With the number of supplements available on today's market, it's easy to get lost and confused, but fear not - our research team has also compiled this ingredient-based guide to help you select the best fat-burning product.

So, let's dive in.

Quick Summary

  • Fat burners don't break a fast in intermittent fasting as they don't contain substances that will spike your blood sugar levels.
  • Intermittent fasting helps in weight loss by reducing insulin levels, which in return triggers the body to burn fat for energy.
  • Studies reveal that fat burners help aid weight loss by speeding up the body's metabolism rate.
  • Ingredients to look for in fat burners for intermittent fasting are HMB, coleus forskohlii extract, black pepper extract, and cayenne pepper extract.

What Kind of Supplements Break a Fast?

pouring scooped collagen in a glass of water

Taking anything that will spike your blood sugar levels, for example, collagen or BCAA supplements will break a fast.

The reason behind this is that amino acids turn into protein, which contains calories that your body has to metabolize, so when you take them, you are signaling your body that you are not fasting.

Intermittent fasting reduces the level of insulin and helps burn fat for energy.

When you break a fast, insulin level goes up and your system stops using fat for energy. [1]

So, when you are intermittent fasting, steer clear from anything that has caloric value or triggers an insulin response.

More extreme forms of fasting exclude everything but water - even plain coffee or tea.

However, most experts agree that it's fine to have sugar and milk-free cup of coffee or tea while intermittent fasting.

The Science Behind Intermittent Fasting (IF)

fork, leaves, small blue clock, measuring tape placed on a plate

As you may know, intermittent fasting is not a diet per se; it's more like an eating pattern inspired by our ancestors' diet.

The idea behind IF is that human bodies work best when cycling between periods of feasting and famine.

Fasting exposes your cells to moderate levels of stress, making them more resilient to oxidative stress and diseases related to that.

A brain hormone norepinephrine, gets released to your fat reserves, triggering fat cells to break down. [2]

It can also help with inflammation reduction, blood sugar control, gut health, and insulin resistance.

Interestingly, some research suggests that fasting can decrease hunger hormone ghrelin and increase satiety hormone leptin, which can be a good tool in suppressing food cravings. [3]

It's a pattern that allows you to prevent overeating and keep an eye on your food and calorie intake.

The popularity of this IF in bodybuilding comes from the fact that this eating pattern might help burn fat while preserving muscle, but it also comes with an array of other health benefits.

What Are the Benefits of IF?

woman holding a paper with a smiley face to his stomach wrapped in measuring tape

When used correctly, intermittent fasting can do amazing things to your body. In recent years, there has been much research that confirms its role in:

  1. Inflammation reduction - limits the damage caused by free radicals
  2. Promoting fat mobilization - helping you achieve a healthy balance of fats (aka body composition)
  3. Hormone balance - IF can stimulate the production of testosterone and growth hormone - the key hormones for building muscle
  4. Cell repair (autophagy)
  5. Keeping your blood sugar levels in check - When you are constantly eating, insulin in your bloodstream spikes, but when fasting, your insulin is low, forcing your body to use the stored energy in the form of fat and glycogen.

Although IF on its own can be a great tool to break into your body's fat storage and help you lose weight, adding fat burner supplements can make it twice as efficient and accelerate fat loss.

Does IF Cause Muscle Breakdown?

man in a white shirt holding his painful shoulder

According to some researchers, it appears that intermittent fasting doesn't cause more muscle loss than any other continuous calorie restriction diet.

That being said, it's also important to note that without exercise, weight loss usually results in the loss of both fat mass and lean mass.

But there is a way around it: "If you get enough protein in your feeding period, fasting for 16 hours does not appear to be detrimental to your muscles, compared to a normal diet"

- Grant Tinsley, Ph.D.,

Although taking dietary supplements during fasting periods is not always necessary, creatine and protein may play a role in maintaining muscle mass - just be sure to take them during the feeding periods of your intermittent fasting.

Additionally, if you're looking to optimize your muscle preservation during fasting while maximizing your fat loss journey, incorporating fat burners into your routine can be beneficial.

Look for fat burners that contain ingredients like HMB, a metabolite of leucine known for its ability to protect muscle tissue, reduce muscle degradation, aid recovery, and enhance energy levels during fasted training.

Choose fat burners that align with your goals and complement your intermittent fasting regimen.

Is Exercising On an Empty Stomach Good For You?

woman in black underwear with a question mark paper on her stomach

Combining fasted training with the right kind of fat burner can be a fat loss jackpot, but it really depends on the type of workouts you're doing and the goal you are after.

For example, intense exercise in a fasted state can lead to muscle degradation because your system breaks down amino acids to preserve sufficient blood glucose levels, which can lead to an increase in stress hormone and a depressed immune system.

So, fueling up before high-intensity sessions longer than 90 minutes is a good idea if you want to avoid spending all of your energy midways through your session.

As for weight and strength training, "lifting weights while fasting is not recommended, especially during heavy lifting sessions or if your goal is to build muscle. For best results, lift weights during the window of time that you're eating"

- Lisa Booth, Nutritionist at

So, yes, feel free to hit the gym on an empty stomach, but keep your activity light to moderate and don't forget to supplement.

How Do Fat Burners Work?

container and white pills surrounding it

Fat burners should aid fat loss by speeding up your fat metabolism, increase your fat oxidation during exercise, and aid weight loss.

By moving fat into the bloodstream, good fat burners help you use stored fat to fuel exercise.

Fat burners can work in three different ways:

  1. They trigger thermogenesis, which raises your body temperature to burn more calories
  2. Can reduce overeating and snacking
  3. Boost energy

They contain additional ingredients that protect lean muscle mass. This aspect of a fat burner is crucial when following the intermittent fasting diet.

To achieve this, most of them rely on stuff like caffeine, L-carnitine, green tea, coleus forskohlii extract, chromium, Raspberry Ketones, Yohimbe, and Glucomannan.

Choosing the right formula and right doses is crucial to maximizing fat burners' potential, but the thing is, you'll often encounter products that are jam-packed with stimulants and additives that can make you feel worse when taken on an empty stomach.

So, let's get into tips and tricks on selecting the best fat burner to complement your intermittent fasting regimen.

Choosing the Right Fasting-Friendly Fat Burner

women holding up different types of sachet pills

The fitness industry is flooded with fat burners of all shapes and sizes, ranging from awesome to terrible formulas, so choosing the best fat burner can be challenging.

Low-quality fat burners rely on stimulants, such as caffeine, which ramps up epinephrine levels, giving you the energy to work out longer at the gym, but this makes sense only to some extent.

The effectiveness of caffeine-packed fat burners is limited, and they often come with side effects ranging from jitters, insomnia, fatigue, and more serious health issues.

On the other hand, a good fat burner should be stimulant-free and loaded with ingredients that trigger the breakdown of fat stores, increase thermogenesis, speed up the metabolism and stimulate hormones responsible for effective fat reduction and weight loss.

To get the most bang for your buck, choose a product that's clean and 100% natural.

Nowadays, you can find diet pills with ingredients that are grown via a process called nutrigenesis, which means all ingredients are obtained in controlled lab conditions that replicate what is found in nature, helping you absorb and utilize it quickly and efficiently.

What Ingredients To Look For in a Fat Burner for Intermittent Fasting?

close up image of fresh cayenne pepper, and a spoonful of black pepper

Although intermittent fasting does great things for your body and mind, like keeping your insulin levels in check and curbing food cravings, adding a well-rounded supplement can turn you into a fat-burning and muscle-building machine.

So, let's check out the qualities and ingredients that you should look for on a product label:  

HMB (Hydroxy Methylbutyrate)

This is the ingredient to look for if you're aiming for a jacked-up physique.

HMB is responsible for increasing muscle strength during a workout and preserving lean muscle mass during intermittent fasting, so it's no wonder that it's commonly found in supplements for bodybuilders.

HMB also improves oxygen consumption, which helps burn more calories per session.

HMB influences the strength and lean body mass by acting as an anticatabolic agent, minimizing protein breakdown and damage to cells that may occur with intense exercise. [4]

In short, HMB is a training intensity amplifier that builds and preserves muscle in calorie-restricted fitness programs.

Coleus Forskohlii Extract (Forskolin)

coleus flower

In theory, diet pills containing forskolin can promote weight loss by creating enzymes called adenylate cyclase and lipase.

These two enzymes free fatty acids from the cells, which can then be burned as fuel.

This process is known as fat oxidation.

When the body burns fatty acids, it may promote fat breakdown without affecting lean muscle mass. [5]

Both Coleus Forskohlii and HMB have the ability to preserve muscle mass and boost muscular strength during a workout.

Not only will this fend off catabolism during fasting, but it will also promote muscle growth during strength training, which some studies suggest is harder during intermittent fasting.

Related: Does Forskolin Increase Testosterone?

Cayenne Pepper Extract (Capsaicinoids)

Eating spicy food not only makes you sweat but according to some research, capsaicinoids in cayenne pepper can promote thermogenesis, causing you to burn calories.

Choosing a fat burner with cayenne pepper can raise your body temperature, adding to the number of calories you burn at rest.

Black Pepper Extract (Piperine)

Just like cayenne pepper, black pepper extract does a great job as a thermogenic. On top of that, piperine may slow down the creation of new fat cells. [6]

This ingredient is an excellent addition to any fat burner, thanks to its ability to promote absorption of the other ingredients.

GTF Chromium

Chromium is an essential mineral commonly found in foods such as meat, vegetables, and shellfish. The GTF in its name stands for glucose tolerance factor – a reference to its potential to regulate the metabolism of carbohydrates.

Many studies have shown that chromium can help in appetite control and regulation of fats and cholesterol levels, but it can also raise your energy levels and boost performance while exercising.

GTF Chromium is also now known to be beneficial for people with type 2 diabetes, metabolic syndrome, and insulin sensitivity.

Related Articles:

What's the Best Time To Take Fat Burning Supplements?

woman holding a cup of water and a yellow pill in one hand

Unlike creatine or BCCAs, taking fat burners won't spoil your fast, but of course, the timing will depend on your intermittent fasting schedule and what you want to achieve (e.g., fat loss vs. weight loss).

Before breakfast 

You've probably noticed that the instructions on thermogenic products state to take the dose on an empty stomach to allow the supplement to be absorbed faster so you can benefit from its effects in a flash.

Taking your fat burner a half hour before breakfast will give time for your metabolism to speed up after a good night's sleep and help not only with the fat-burning process but also with appetite suppression throughout the day.

Before workout

If you need that extra kick of energy to get you through a grueling workout and burn more calories per session, taking fat burners right before working out should be your choice.

With meals

This is a good option for people with a more sensitive digestive system. Having fat burners with food can reduce the risk of stomach irritation and discomfort.

Related Article: Best Fat Burners For Vegans

What Are the Benefits of Taking Fat Burners When Fasting?

woman holding a sachet of pills with her thumbs up

Taking a fat burner while intermittent fasting, especially in conjunction with fasted exercise, may help improve your fitness results by:

  • Promoting Pre-Workout Thermogenesis
  • Increasing energy, muscle stamina, and exercise endurance
  • Limiting Fat Storage and Balancing Blood Sugar
  • Protecting Hard-Working Muscle Tissue
  • Control sugar cravings and food intake, helping you achieve healthy body composition

So, Is It Okay To Take a Fat Burner While Fasting?

There is more than enough science-backed evidence that these two go hand in hand.

This is a combination that can not only take your fat-burning potential to the next level but can also help you maintain your lean muscle mass while intermittent fasting.

If you throw in fasted exercise, you can be sure that your body fat will melt away like ice cream on a hot summer's day.

You should try to choose a fat burner supplement with thermogenic properties that can support calorie loss, is stimulant-free, and has other ingredients that can protect your muscles.

Also, don't underestimate the power of food.

Use your eating window wisely; avoid binge eating, take sufficient protein, consume enough fruits and veggies and other healthy stuff to supply you with nutrients when dieting.

If you have tried mixing fat burners and intermittent fasting, share your experience in the comments below.


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