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Are Fat Burners Actually Dangerous? (Revealed)

Tyler Sellers
Published by Tyler Sellers | Senior Coach
Last updated: August 13, 2023
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Most of my fitness clients have questions about supplements, including if any of them include dangerous ingredients.

A recent conversation about fat burners prompted me to consult our dietician to discuss such questions as: “do they contain too much caffeine?” or “are there any harmful effects?”

If you are considering taking a fat burner and are concerned about their safety, read on.

Quick Summary

  • Fat burners are not dangerous for most people, but it is advisable to always consult your doctor before consuming them.
  • The miracle pills increase metabolism, suppress your appetite, and also reduce the fat levels absorbed in the gut.
  • Some ingredients found in fat burners are caffeine, green tea, fiber, and CLA.

Fat Burners: Are They Dangerous?

Supplement pills on carpet

Fat burners are likely not dangerous for most healthy individuals.

However, discussing any supplement with your doctor to determine how it will affect any health conditions or interact with any medications you take is always paramount.

To evaluate the safety of fat burners, we looked at how they work and their active ingredients.

Let’s take a look now.

How They Work

Fat burners are not miracle pills that make fat magically disappear. What they might do, however, is:

  • Increase metabolism, so you burn more calories
  • Reduce the fat your gut absorbs
  • Suppress your appetite, leading to fewer calories consumed and helping you lose weight

None of these mechanisms of action, in and of themselves, is likely to cause any harm to healthy individuals.

But let’s zoom in a bit further to evaluate common ingredients that might be problematic for some.

4 Common Ingredients

Some ingredients commonly found in supplements to help burn fat include the following:

1. Caffeine

A cup of coffee close up image

Caffeine is the top ingredient in most fat-burning supplements because studies show that it can significantly impact energy expenditure and promote thermogenesis [1].

Increased resting metabolic rate (RMR), the number of calories burned while the body is at rest, aids energy expenditure. Caffeine increases RMR by as much as 11% [2].

Additionally, studies suggest that caffeine aids fat mobilization from the fat cells. Caffeine is a central nervous system stimulant that directly signals the fat cells to break down fat by increasing adrenaline (epinephrine) [3].

Caffeine is also known to increase blood pressure slightly, or when used in excess amounts, especially for caffeine-sensitive individuals, it might cause dehydration, headaches, stomach upset, or jitteriness [4].

But for healthy individuals, and when used in adequate amounts, it poses no danger whatsoever.

2. Green Tea

Look at many fat burner ingredient labels, and you will likely see green tea extract because it can mobilize fat from the fat cells because of its caffeine and EGCG content.

EGCG is the primary antioxidant found in many teas, particularly green, which can boost the levels of norepinephrine, resulting in increased fat burning [5].

Along with boosting exercise performance, many studies support the theory that the extract enhances fat oxidation, particularly during a workout [6].

However, this same beneficial antioxidant can also cause some unwanted effects, especially when consumed in excess. It might contribute to anemia or affect the liver negatively [7].

For these risks and any potential drug interactions, always make sure to consult with your doctor prior to including green tea in your diet.

3. Fiber

Using a water soluble fiber

Certain fat burners take a different approach by using water-soluble fiber, like glucomannan, instead of heavy doses of stimulants.

Research suggests that consuming 30 grams of fiber daily is enough to promote weight loss [8].

Fiber increases satiety, and this feeling of fullness will likely reduce calorie intake, especially snacking, which will help you maintain a calorie deficit, the key to inhibiting weight gain and promoting weight loss.

“Like other soluble fibers, glucomannan absorbs water in your stomach and contributes to feelings of fullness. In addition, it may promote reduced calorie intake and weight loss in other ways.”

- Atli Arnarson BSc, PhD

Although generally safe, glucomannan supplements can sometimes present a choking hazard as they absorb a lot of water, so make sure to keep that in mind when consuming them [9].

4. Conjugated Linoleic Acid (CLA)

CLA is a fat primarily found in dairy and meat and is added to some fat burner supplements for its potential to enhance fat metabolism.

Though many animal studies show promise in CLA’s effect on reducing body fat, the results in human studies are less concrete [10].

The CLA found in supplements is a different form than derived from food intake. A 12-week study showed decreased adipose tissue and increased lean muscle mass with CLA supplementation [11].

CLA is generally considered safe, but it may be responsible for some digestive issues, so keep that in mind as well [12].

How to Safely Use Fat Burners

Close up image of spilled white pill supplements

The promise of burning fat with all-natural ingredients comes with nearly all weight loss supplements.

Just because ingredients are all-natural and easily obtained through diet doesn’t mean you shouldn’t consider some things before taking them in supplement form:

  • Consult your doctor: talk about any underlying health conditions and how the ingredients in the supplement will interact with any medications.
  • Take the proper dosage: Don’t assume taking more will lead to more weight and fat loss.
  • Purchase from reputable sources: The FDA doesn't regulate supplements like medications. To ensure the safety and quality of any supplement, look for products that come from FDA-approved, GMP-certified facilities that are third-party tested.

Side Effects

As discussed earlier, taking fat burners may come with some generally mild risks.

Here’s a list of some side effects of fat burners reported by users:

  • Stomach issues
  • Diarrhea
  • Dry mouth
  • Itchiness
  • Jitters
  • Acne
  • Hot flashes
  • Nausea
  • Vomiting
  • Nervousness


Do Fat Burners Cause Liver Damage?

Overusing fat burners can cause liver damage, including causing acute liver failure [13]. It is always advisable to consult your doctor to discuss any fat burner supplement ingredients, underlying health conditions, and medication interactions.

Do Fat Burners Affect Your Heart?

Fat burners may affect your heart. Some problematic fat burner ingredients might cause issues like irregular heartbeat or high blood pressure [14]. The FDA does not regulate fat burners, so one of the ways to ensure quality and safety is to purchase from reputable sources.

So, Are Fat Burners Dangerous?

Fat burners promise fat loss with all-natural ingredients that increase metabolism and decrease fat absorption.

I have seen remarkable results in my fitness clients implementing a fat burner into their fitness routine with proper diet and exercise.

Here at Total Shape, we recognize that choosing the right supplement can be daunting, so we test products for quality and efficacy and report the best ones we find.

Click the links below to find our number-one picks:


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