Complete Guide to Fat Burners

Complete Guide to Fat Burners

The term fat burner is used to refer to all dietary supplements that increase fat metabolism or energy expenditure, which reduce the absorption of lipids or carbohydrates from foods, increases weight loss, Increases the oxidation of fat during physical exercise, or anything else that causes more or less long-term increase in lipolysis, decreased appetite or reduced fat absorption.

Complete Guide to Fat Burners


The most popular fat burning supplements are caffeine, carnitine, green tea, conjugated linoleic acid, forsklin and taurine. There are some less known, such as ephedrine from the ephedra plant, capsaicin which decreases the appetite, or clenbuterol.

We will see in this file the different types of fat burners with their operating principles, then the main supplements in detail.

The different types of fat burners


Thermogenics are supplements that will literally help burn fat.

These are effective in dislodging stubborn fat stored in adipose tissue. The resulting energy of thermogenesis can be used to ensure muscular work or to increase the internal temperature of the body. Caffeine is the most popular supplement in this category. Yohimbine is also very much in vogue on the other side of the Atlantic in spite of a rather small number of scientific studies about it.

The stimulants

Caffeine, ephedrine and ephedra are stimulant ingredients prevalent in most fat burners. In France, ephedrine and ephedra are banned and although they are over-the-counter in some countries, these substances are banned by the International Olympic Committee (IOC).

These stimulants that increase alertness can have side effects in some people: nervousness, heart palpitations, digestive problems …

Carb blockers

Carbohydrate blockers contain ingredients that prevent the functioning of certain digestive enzymes, those whose function is to break down carbohydrates into simple sugar. Because of this, the carbohydrates you ingest can no longer be assimilated because of their “too large sizes”. The caloric intake and the secretion of insulin are therefore reduced.

These blockers contain extracts of white bean which contains a substance to reduce digestion and thus the absorption of starch.

This means that if you give yourself sweets or other sources of simple sugars, this supplement will have no effect. It will be effective with foods like bread, potatoes, pasta, etc. To learn more about the different types of sugars, read our special carbohydrate file.

The main disadvantage of these carbohydrate blockers is the production of gas in large amounts causing bloating and abdominal pain. This is due to the fact that there are bacteria present in the colon, which will ferment excess carbohydrates.

Another side effect: lowering blood sugar and therefore decreasing energy that can lead to discomfort.

For these reasons, it is highly recommended to seek the advice of a physician before taking this type of supplement or medication.

Lipid blockers or “Fat Blockers”

The same principle as the carb blockers, but this time, it is the lipids whose assimilation is limited. One of the main ingredients of these fat blockers is chitosan (also found under the name of chitosan).

Chitosan has the ability to bind chemically to lipids, up to 15 times its own weight. Since this macromolecule can not be metabolized, the lipids are not assimilated by the body: they are therefore eliminated in the stool.

There is also a drug (Orlistat) marketed under the trademark Xenical at Roche or Alli at GlaxoSmithKline and non-prescription drugs of type XL-S medical fat sensor. Orlistat inhibits intestinal enzymes called lipases, whose job is to break down the fat.

The problem with these fat blockers is that it also prevents the assimilation of  fat-soluble vitamins that the body needs to stay healthy.

Thyroid Regulators

The thyroid is an endocrine gland lodged in the neck that regulates among other things the basic metabolism . Its function is to control how the body burns energy and makes proteins. This organ also regulates the body’s sensitivity to other hormones.

If your thyroid gland does not work optimally, it will no longer secrete enough hormones and your metabolism will slow down. To avoid this, there are thyroid stimulators that help boost metabolism and therefore help to lose weight.

Among the ingredients to boost the thyroid are iodine and plant extracts such as commiphora mukul, chondrus crispus and laminaria digitata.

The appetite suppressants

Also known as anorectics or appetite suppressants, they are substances (supplements or drugs) that reduce appetite and lead to eating less.

Like all other types of fat burning drugs, do not buy anything on the internet and even less without the advice of a doctor. You may have heard about Meridia, the slimming pill to treat obesity. This slimming drug that can be purchased from unscrupulous sellers was withdrawn in 2010 following numerous heart and brain accidents caused by the active ingredient, sibutramine 1 .

Among the supplements that help stop the cravings for nibbles , hoodia gordonii is a very popular plant. Unfortunately, this plant known to be a natural appetite suppressant, used for hundreds of years by the indigenous populations of South Africa is not allowed in France.

If you are looking for natural appetite suppressants with no side effects, look for fatty , high-fiber, bulky, low-energy foods.

Cortisol blockers

Cortisol is a hormone released by the adrenal glands. This hormone often referred to as “stress hormone” increases blood pressure, blood sugar levels and weakens the immune system.

As the cortisol increases, appetite and fat storage increases. In other words, every time we are in stress, cortisol increases in the body, and tells our brain that we are hungry, while activating the storage of triglycerides in adipocytes. Cortisol blockers can prevent these negative repercussions.

Fat burner supplements


Caffeine also acts as a stimulant and increases the release of adrenaline and norepinephrine in the body, also known as “theine”, “guaranine” or “mateine”.

These neurotransmitters or vigilance hormones accelerate the degradation and combustion of fatty acids , making them available as fuel sources. Caffeine also acts as a mild anorectic.

All the benefits of the effects of caffeine on metabolism stem from physiological studies carried out in the 1970s. The first studies 2 demonstrated that caffeine ingested before physical exercise significantly raises the rate of oxidation of fats, As well as performance.

This mechanism occurs indirectly by increasing the circulating rate of adrenaline (which has the potential to improve the availability of fatty acids for their oxidation).

Caffeine also provides a short-term thermogenic effect 3 4 5  caused by increased oxidation of fat.

Caution, by consuming caffeine regularly, you decrease your sensitivity to this stimulant, and over time, these benefits become zero 6.

The advantage of consuming one or two espressos before each training is therefore questionable: one should not deny the placebo effect.

Absolutely, it is better to consume caffeine cyclically to make the most of these benefits.

Plants containing caffeine

  • Guarana : this Amazonian plant contains the highest concentrations of caffeine, between 3.5 and 5.8% of its volume. In comparison, coffee has a maximum of 2%.
  • Tea : Tea leaves (camellia sinensis) allow the preparation of the most drunk beverage in the world after water. This makes it the most popular thermogenic to lose weight. The caffeine of tea represents between 2.5 and 5% according to the varieties. Green tea also contains a powerful antioxidant, epigallocatechin gallate (EGCG), a beneficial health-promoting polyphenol.
  • Yerba mate : a popular South American herb, with a caffeine concentration between coffee and tea leaves.
  • Coffee : Originating in East Africa, coffee is a shrub mainly used for its caffeine. Prefer the consumption of green coffee, much richer in antioxidants.
  • Cocoa : these beans are used to make chocolate. 100 g of dark chocolate is equivalent to the amount of caffeine in an espresso (43 mg).
  • Kola nuts : a traditional source of caffeine in African countries, its caffeine content is slightly higher than that of coffee.

Cayenne pepper

Cayenne Pepper contains capsaicin, a powerful antioxidant that activates the skin’s heat receptors, resulting in the burning sensation. But that’s not all.

Several studies have shown that capsaicin increases energy expenditure , with more fat burned 7 8 9. This increase in fat metabolism is due to a significant secretion of adrenaline and noradrenaline, caused by capsaicin.

If you are sensitive to anything that is spicy, you can buy extract of Cayenne pepper as a dietary supplement.

Caution, capsaicin can cause heartburn. Start with small amounts to test your tolerance.

That is to say : neither the cooking, nor the drying or the freezing do not overcome the capsaicin. There is a single protein that you know surely that can neutralize it, this is casein , a milk protein. If you do a Chile Challenge, do not drink water to put out the fire, but dairy products like milk, cheese, yoghurt or casein shake!

Conjugated linoleic acid (CLA)

This essential fatty acid belonging to the family of omega-6s is one of the healthiest slimming supplements over a long period.

It has many positive effects on energy metabolism , adipogenesis, inflammation, lipid metabolism and adipocyte apoptosis 10.


This essential trace element that helps to metabolize carbohydrates and fats is the source of a huge media hype and marketing. Chromium alone helps the body to increase muscle mass, promote fat loss and reduce appetite.

It is marketed mainly in the form of chromium picolinate, chromium nicotinate, or even chromium chloride. Picolinic acid is an organic compound that binds to chromium and promotes its absorption and transport.

Caution, never exceed the recommended doses. Indeed, a study carried out in 1995 suggests that an excess of chromium can cause chromosomal lesions 11 , in other words cancers.


Carnitine is a molecule produced in the body that is naturally found in meat, fish, and dairy products. This compound is involved in the transport of long chain fatty acids through the mitochondrial inner membrane.

Carnitine supplementation improves fat metabolism, reduces fat mass and increases muscle mass. This supplement is also used by endurance athletes to increase fat oxidation and therefore performance.


The active principle of the plant coleus forskohlii, forskolin stimulates an enzyme (lipase), which hydrolyzes triglycerides stored in adipocytes. This ingredient is present in many supplements for drying, including the famous Hydroxycut Hardcore from MuscleTech or Animal Cuts from Universal Nutrition.

The cider vinegar

Cider vinegar (ACV for Apple cider vinegar) is a natural remedy, used by many as a preventive measure, more than curative.

The most interesting study on how cider vinegar helps to slim was published in 2009. Published in the journal Bioscience, Biotechnology, and Biochemistry 12 , the study concludes that drink 2 tablespoons of vinegar for 2 months Can help to lose weight, especially abdominal fat, resulting in a reduction in waist size.

Regarding its mechanisms of action, it is now known through numerous studies that it acts as an appetite suppressant and that it improves the sensitivity to insulin 13 .

Fat burners prohibited


A popular ingredient in bodybuilding before 2000, especially in the ECA fat burner cocktail (ephedrine, caffeine, aspirin), this Chinese herb named ma huang or ephedra is banned in many countries including France. This stimulant of the central nervous system, cardiovascular, respiratory, and digestive and urinary sphincters causes numerous and frequent adverse effects, such as heart attacks and strokes.

Bitter orange

The bark of bitter orange is one of the most fat burning foods to reduce the fat mass. It contains synephrine, a compound chemically similar to ephedra. Although this thermogenic plant can help promote weight loss, it can also contribute to heart disease and other serious health problems.

Garcinia Cambogia

Also found under the name of Malabar tamarind tree, this small berry can suppress appetite and boost metabolism. However, this effect has been demonstrated only in animals. Although garcinia cambogia helps reduce the accumulation of abdominal fat, it also brings its share of negative health effects including liver disease.


Clenbuterol is one of the most potent (and dangerous) thermogenic. Used in bodybuilding to increase muscle definition, its consumption results in tremors, hyperhidrosis (excessive sweating), cardiac arrhythmias and muscle cramps. Studies also show that clenbuterol may cause enlargement of the aorta after physical exercise, increasing the risk of aortic rupture and sudden death.

FAQ on fat burners

Do fat burners really work?
Yes, fat burners can actually help in losing fat, but with the condition of following an appropriate diet. It is a “complement”, not a miracle capsule. If you consume more calories than you need, nothing will help you lose weight.

When to take a fat burner?
The best time is in the morning to wake up, especially for thermogenics and stimulants like caffeine. These can also be taken 30 minutes before physical activity, unless you train at the end of the day. In this case, take them only in the morning if you want to have a good sleep.



  1. Sibutramine (Sibutral®) : Suspension de l’autorisation de mise sur le marché – Communiqué
  2. Effects of caffeine ingestion on metabolism and exercise performance
  3. Caffeine and coffee: their influence on metabolic rate and substrate utilization in normal weight and obese individuals
  4. A simple apparatus for comparative measurements of energy expenditure in human subjects: the thermic effect of caffeine
  5. Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers
  6. Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation
  7. Administration of capsiate, a non-pungent capsaicin analog, promotes energy metabolism and suppresses body fat accumulation in mice
  8. Sensory and gastrointestinal satiety effects of capsaicin on food intake
  9. Combined effects of red pepper and caffeine consumption on 24 h energy balance in subjects given free access to foods
  10. Antiobesity Mechanisms of Action of Conjugated Linoleic Acid
  11. A prediction of chromium(III) accumulation in humans from chromium dietary supplements
  12. Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects
  13. Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects

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