“Fat burners”, or thermogenic drugs

Sports nutrition

What is

Fat burners, or “diet” pills, according to manufacturers, accelerate metabolism and reduce fat mass. The main ingredient is ephedrine, or ephedra-a stimulating substance obtained from the Chinese plant ma Huang. It is often combined with caffeine and aspirin. Endurance athletes and strength athletes usually take fat burners to increase the intensity and duration of exercise and contribute to weight loss.

Ephedrine in low concentrations is also used for colds and flu (pseudoephedrine).


Athletes use fat burners, as they increase thermogenesis (burning calories) and accelerate metabolism. They create a “speed” effect, providing a feeling of greater readiness, motivation and confidence; they also increase heart rate and blood pressure. The combined intake of ephedrine and caffeine seems to enhance the effects of each of these substances. Sometimes aspirin is added to fat burners, which can prolong the stimulating effect of the latter. No one knows the exact effect of fat burners, but it is believed that when they are taken, the nervous system is temporarily overloaded, which leads to increased heat production (thermogenesis) and the release of fat reserves. Studies show that these supplements do increase fat burning when following a low-calorie diet, although this effect weakens over time. The problem with fat burners is that they can lead to adverse side effects (see below).

Do you need them?

Fat burners are addictive drugs, and I would strongly recommend avoiding any fat burners containing ephedrine (or ma huang) due to significant health risks. The International Olympic Committee (IOC) prohibits ephedrine. Physical activity and appropriate nutrition are the safest method of fat burning.

Side effects

A dose of up to 25 mg at a time is considered safe in the treatment of colds; higher doses may be required to create a stimulating effect. The doses required for the fat-burning effect are quite high and are associated with many dangerous side effects, including increased and irregular heartbeat, increased blood pressure, insomnia, anxiety, nausea, irritability, dizziness and other manifestations of increased excitability. In addition, cases of more serious consequences of high doses, such as heart attack, stroke and death, have been reported in the medical literature. Taking a mixture of “ephedrine-caffeine-aspirin” increases the likelihood of side effects even at low doses. Thus, the risks far exceed any potential benefit.

Fat burners (without ephedrine)

What is

Some fat burners and weight loss supplements are advertised as products that mimic the effect of ephedrine, that is, they accelerate metabolism and fat burning, but without adverse side effects. The main components of such products are orange (synephrine, or bitter orange extract), green tea extract and folius forskolia extract (a plant similar to mint).


Orange is a weak stimulant, chemically similar to caffeine and ephedrine. It contains a chemical compound – synephrine, which, according to manufacturers, reduces appetite, accelerates metabolism and provides fat burning. However, despite these statements, there is no significant scientific evidence that would confirm the effect of weight loss.

The active components of green tea are polyphenols, which are known as catechins (the main representative is epigallocatechin gallate), and flavanols, which have a powerful antioxidant effect. In addition to the obvious benefits of green tea as an antioxidant, initial studies suggest that it can also stimulate thermogenesis, increasing calorie consumption, providing fat burning and weight loss.

The theory underlying the use of coleus forskolia extract as a dietary supplement is that the forskolin contained in this plant should stimulate the activity of adenyl cyclase, which should increase the level of cAMP in fat cells, and this, in turn, should lead to the activation of another enzyme – hormone – sensitive lipase-and, thereby, trigger the mechanism of splitting fat reserves. However, there are no published trials demonstrating that coleus forskolia extract provides weight loss.

Do you need them?

All studies regarding the actions of fat burners that do not contain ephedrine are unintelligible and unreliable. The effects that these fat burners give are relatively small or completely absent. The doses used in some brands may be too small to provide a significant effect. Careful calorie intake and exercise are likely to provide more noticeable and long-term weight loss. Positive information is given only about green tea, but to achieve a significant fat-burning effect, it is necessary to drink at least 6 cups of tea daily (equivalent to 100-300 mg of epi-gallocatechin gallate).

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