Early weight gain in children linked to ability to produce the hormone leptin

Leptin levels vary between individuals, however, and around 10 to 20 percent of individuals with obesity have the same leptin levels as individuals with normal weight. This variation raises questions about the role leptin plays in regulating weight.

In the study scientists screened the genome of more than 55,000 people for genetic variants that affect leptin levels. They identified five new genetic variants that play a role in regulating leptin levels.

Leptin may play a stronger role in weight control in children, than adults.

One of the variations, Vel94Met, which reduces the amount of leptin that the body produces, is only found in individuals of African ancestry. Young people with this variation are more at risk of developing obesity, though this is not true of adults with the variation, who tend to be of similar weight as other adults.

This finding supports the theory that people become less sensitive to leptin with age. Administering leptin to obese adults has proven ineffective at controlling their weight.

"This new knowledge on the impact of leptin in the weight control of young people now needs to be followed up with further studies to uncover the molecular mechanisms that underlie this age-dependent relationship between leptin and BMI," says Associate Professor Tuomas Kilpeläinen.