How Do Fat Burners Work

How Do Fat Burners Work? (The Magic Weight Loss Pill Myth…)

Over the last few years, the number of people using fat burner supplements has absolutely exploded.  

Whether it’s the increased awareness in a social media world, people genuinely caring more about getting fit and healthy, or simply the impact of tens of thousands of influencers pushing products on Insta, fat burners seem to be everywhere. 

But is it possible to just take a fat burner for a week, then walk out onto the beach with the physique of a fitness model? Do fat burners actually work without exercising alongside their use?

Like all things fitness, the answer is more complicated than a simple yes or no. Here’s what you need to understand if you’re planning on taking them as we explain just how do fat burners work below: 

What Is a Fat Burner

Fat burners are supplements that are supposed to help you strip the excess pounds from your frame, trim you down, and shred your body fat. Most fat burners come in easily accessible daily pill form, and promise to help you lose fat without changing anything about your current diet or activity levels.   

The good news is, fat burners do work… To an extent. 

Yes, they can burn away pounds of fat if all you do is take the supplement but only if it is taken as a supplement to an optimal diet and fitness regime targeting overall weight loss. 

The absolute truth is that fat burner supplements work much better if they’re used alongside a good diet and an effective exercise plan. 

This means that taking a fat burner by itself might help someone shed a couple of pounds of excess fat but it’s not a guarantee and a few pounds may be the absolute limit! 

But a fat burner is much better suited if you already have a fitness routine in place, and you’re looking to kick start rapid fat loss or put the finishing touches on a physique. 

How Does a Fat Burner Work?

Nearly every fat burner is going to work in roughly the same way. Providing supplements that increase your metabolism, or total daily energy expenditure (TDEE.) 

Your TDEE is the number of calories you burn at your current height, weight, and level of physical exertion. It’s also sometimes called your maintenance level, as it’s the number of calories you need to consume to maintain your current weight if nothing else changes. 

Check out this popular TDEE calculator to see your own results. 

The active ingredients in fat burners increase this number, which means that you’re going to burn more calories at rest, every day, without having to change anything else. 

This means that fat burners don’t specifically burn fat. Instead, they increase your body’s caloric expenditure, encouraging your body to burn more calories than you’re taking in. 

This matters because your body will burn any available resources to fill that caloric deficit, so it’s important that you take steps to encourage your body to burn fat, instead of muscle. 

How do Fat Burners Work?

The main ingredient in a lot of fat burners is caffeine, often in the form of green tea extract or anhydrous (dehydrated) caffeine. Caffeine is a stimulant that already has verified medical support in its effect on increasing metabolism and helping specifically to help the breakdown of adipose tissue; burning away fat, as promised.

Caffeine also helps provide energy and mental focus, as anyone who relies on their morning cup of coffee to function will attest. This can function like a pre-workout, which contains high doses of caffeine for precisely this reason. 

Many fat burner supplements also have ingredients that are designed to help you lose the fat using other methods, including:

  • Reducing the amount of fat your body absorbs when digesting food
  • Increasing blood pressure to further increase metabolism
  • Suppressing your appetite, so you naturally eat less

How Your Body Burns Fat

Your body stores excess energy as fat. If you’re consistently eating more calories than you need, they’re stored away for later, an evolutionary adaption to stop you starving in case there are leaner times ahead. 

The good news is that this means the path to losing fat is simple. Burn more calories than you’re using. Anyone who’s heard about the keto diet is probably aware that there are ways to encourage your body to burn fat and build muscle. 

Fat burners work in a similar way. 


Thermogenesis (lit. heat production) is part of the process where your body naturally burns calories even when it’s completely at rest. 

The ingredients in fat burners help to boost your resting metabolism, can increase your internal body temperature, and sometimes also increase blood flow to your muscles and organs by increasing blood pressure.

All of these things encourage your body to burn more calories, and in concert with exercise and a good diet, can have a huge effect on overall weight loss.  

How Quickly Can You Lose Fat Using a Fat Burner?

It’s common for people to hear the term fat burner and imagine some magic bullet that’s going to strip off pounds of fat in a week.  

Nothing is further from the truth. More importantly, you don’t want this to be true. 

There is a limit to healthy weight loss. Studies show that losing around 1 to 2lbs of fat per week is optimal. Any more can cause a host of negative health effects, including dehydration, muscle loss, lowered metabolism, and other, more serious issues. 

Do You Need To Exercise While Using a Fat Burner?

As already mentioned, while you don’t need to exercise when you’re taking a fat burner, however, the results if you do are significantly better.  

Before reading on, it’s worth noting we’ve produced a more detailed article on whether fat burners will work without exercise that’s worth checking out separately. 

But there’s another point to keep in mind. Because the main active ingredients in many fat burners are caffeine and other stimulants, taking a fat burner could increase your energy levels and give you a boost of focus and energy. 

This means that your fat burner supplement might work similarly to a pre-workout formula if you take it a short time before you head to the gym, contributing to better workouts and overall fitness and health. 

Are There Any Other Side Effects to Using Fat Burners?

A fat burner supplement that contains high amounts of caffeine and other stimulants may contribute to increased heart rate and blood pressure, in the same way that consuming large amounts of caffeine from other sources (e.g. coffee) would.

Stimulants like caffeine can also have an effect on mood, increasing irritability, and might affect sleep. 

The last thing to be aware of is that use of fat burners can lead to dehydration. If you choose to supplement, make sure that you’re drinking enough water to stay properly hydrated throughout the day. 

Final Thoughts

A fat burner is a supplement, and like all supplements, they’re not a substitute for the core tenets of fitness. 

Fat burners work by raising your metabolic rate and core body temperature through thermogenesis. This is done to promote fat loss, however, it’s not the primary cause of fat loss. 

An energy deficit (or caloric deficit) is the most important thing that will lead to weight loss and a fat burner is only a small tool you can use to contribute to this. They won’t do the work themselves and it’s definitely not the case that you can take fat burners and just instantly see the pounds start to drop off!

For some further info on how to get the maximum impact from a fat burner, check out our other guides below: 
When is the best time to take fat burners
How long do fat burners stay in your system
Should you take fat burners on an empty stomach

What Next

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