Fat burners are comfortably in the mainstream now. Long gone are the days when fat burners were dangerous diet pills you bought from Mexico, or powerful pharmaceuticals you saw advertised on late-night TV and begged for a prescription for. Today, fat burners are widely used and generally considered safe.
But are fat burners really that much safer today?
Natural fat burning supplements today claim to be safe and side effect-free. As you’ll know if you read some of our fat burner reviews, many of these promises are totally untrue! But people generally assume that natural, top-tier fat burners are safe for long-term. However, this might not be the case.
In particular, there is some evidence that fat burners may be harmful to the liver.
Do fat burners cause liver damage?
Let’s take a closer look at how fat burners work, what the side effect risks are, and the long-term dangers.
How do fat burners work?
Fat burner supplements tend to work in a number of different ways. The best fat burners will combine multiple ingredients to promote fat loss and body recomposition in several ways at once, while lower quality weight loss pills will focus on just one or two pathways. But most fat burners work in very similar ways.
One of the main ways that fat burners work is by increasing lipolysis directly. In other words, some high quality fat burners contain ingredients which stimulate the release of stored fat for use as fuel. A prime example here is forskolin, which has been found to directly stimulate stored fat loss. Another example would be EGCG, which increases fat loss independently of exercise.
Another way natural fat burners work is by suppressing appetite. Now there are a number of different ways fat burners do this; some are great, others are not. The best stim-free fat burners usually contain appetite suppressants which work by increasing feelings of fullness. Water soluble fibers are the go-to here, as they expand in the stomach and make you feel full without contributing any meaningful calories. Lower quality fat burners will rely on large doses of stimulants to decrease appetite, which comes with severe side effect risks, and more often than not, a rapid regain of weight once you stop using the fat burner!
This brings us to the next way that fat burners usually work – boosting energy. Almost all fat burners, except caffeine-free fat burners, contain ingredients which rapidly increase mental and physical energy levels. The most common ingredient used to do this is, of course, caffeine. Caffeine quickyl decreases fatigue, increases both mental and pjhysical energy, sharpens focus, boosts motivation, and suppresses appetite.
All of these things sound amazing. Combining energy boosters, appetite suppressants and direct fat burners will accelerate fat loss and make body recomposition efforts a lot more successful. But there’s no such thing as a free lunch! What kind of side effects do fat burners cause?
What are the dangers of using fat burners?
Good fat burners do make cuts much easier and ultimately more successful. Athletes find them invaluable in making weight for a fight or contest without losing too much muscle mass.
However, as stated above, there is no such thing as a free lunch. Benefits always come with consequences, and with fat burners, those consequences can be serious.
Some of the most common side effects associated with fat burners are those associated with stimulant use. These include nausea, anxiety, panic attacks, elevated heart rate and high blood pressure.
There are, of course, other side effects associated with non-stim fat burners. Nausea, stomach cramps, diarrhea, constipation, loose stools and total loss of appetite are all common side effects of fat burners.
More worrying is the potential for liver damage from long-term fat burner use. Many of the herbal extracts used in natural fat burners require a great deal of processing by the liver and kidneys. There is some concern, and a growing body of evidence, to suggest that some fat burners may damage the liver long-term if used incorrectly.
Are fat burners bad for your liver?
Obviously, the answer to this question depends on the fat burner in question. But generally speaking, the answer is “yes”, fat burners can be bad for your liver.
Despite natural fat burners often claiming to have no adverse side effects whatsoever, there is strong evidence that some supplements are associated with severe hepatotoxicity. There have been several cases of acute liver failure attributed to the use of natural fat burners.
In one documented case, a fat burner containing usnic acid (12 mg), propionyl-L-carnitine (500 mg), green tea extract (300 mg), guggulsterone Z and guggulster-one E (10 mg), cyclic adenosine monophosphate (2 mg) and vitamin E (20 IU) per capsule was found to cause fulminant hepatic failure requiring emergent liver transplantation in a young woman. She was otherwise healthy and there was no other identifiable cause of liver failure.
The simple fact is that taking any unusual and untested herbal extracts, amino acids or stimulants in large quantities for prolonged periods will put a lot of stress on the liver. If a fat burner contains unusual ingredients not typically found in the diet, then the liver will likely need to process them before they can be utilized. This is a particular concern with fat burners using synthetic ingredients, untested substances and excessive dosages of stimulants.
To avoid the side effects from fat burners associated with liver damage, it is best to stick to fat burners which use sensible doses of tested ingredients known to have no negative effects on the liver.
Pavel Sadovnik is a leading biochemical scientist with a PhD in biochemical engineering. He has spent decades working in industry as a chemist and pjharmaceutical consultant. He has extensive experience with the supplement industry, and specialises in supplement tsting and formulation consultancy. He is the Editor of NARSTO.