The discovery of the hormone leptin was thought to be a major breakthrough in the battle against obesity.
Unfortunately, leptin could not live up to its hype.
However, researchers from France reported findings which suggest that leptin may be of interest to totally different population.
The major functions of leptin are to decrease appetite and energy expenditure.
It is secreted by adipose tissue and its levels increase with increasing amounts of fat mass. Thus, lean individuals have low levels of leptin, which protects them against starvation. While on the other hand, overweight individuals have increased levels. This should theoretically prevent them from gaining more weight.
However, it was found that these overweight individuals are resistant to the effects of leptin, much like diabetics are resistant to the effects of insulin. Therefore, treatments to increase leptin did not result in weight loss in overweight subjects.
An interesting question is what leptin levels are in an athletic population, because of their specific body composition.
The researcherd compared male rugby players who practiced for more than 10 h/week, with a control group which consisted of regular men who exercised less than 3h/week.
The results for leptin and other hormones are shown in the table.
The athletes had decreased levels of leptin, while their fat mass was higher and their percentage body fat similar to the control group. The researchers speculate that leptin must not be just regulated by fat mass, but also by physical activity.
Athletes have decreased leptin levels.
The results make me wonder if athletes could benefit from exogenous leptin?