According to a study conducted by the Technical University of Munich, environmental, social and behavioral factors make a bigger difference than genes.

In France, 17% of the adult population is obese, which represents more than eight million people. Childhood obesity is a big challenge around the world. In Germany, researchers have studied the impact of genes in the development of obesity. According to their findings, "obesity genes" play a minor role in the success of weight loss interventions while environmental, social and behavioral factors make a bigger difference.

Indeed, the latter are much more important to consider in obesity treatment strategies for children, the researchers suggested. "Distinguishing individuals who are more or less likely to respond to obesity treatment based on their genetic predisposition will not necessarily lead to better treatment success," said study author Melanie Heitkamp, researcher at department of prevention, rehabilitation and sports medicine at the university. Before adding: "Even people with risk variants of obesity-related genes will benefit from a healthy lifestyle, including a balanced calorie diet and regular physical activity."

Over 900 genetic variants

  The study included more than 1,400 young people aged 6 to 19, overweight or obese. All were enrolled in a four to six week program that included daily physical activity, a low-calorie diet, and behavior therapy. The researchers also studied the genes of nearly 1,200 participants. The authors report that some people suffered from a rare form of obesity caused by monogenic abnormalities, but that in most people, no gene could be identified as the cause. The complex interplay between genetics and an unhealthy lifestyle contributes to obesity, the authors say. Studies have identified more than 900 genetic variants associated with obesity. 

“The most significant finding is that the known genetic variants linked to obesity appear to play only a minor role in short-term weight reduction in overweight and obese children,” explained the researcher. Scientists were surprised to find that three of the five statistically significant genetic variants were associated with greater weight loss during the study intervention. This meant that carriers of the most risky genes lost more weight than expected with these lifestyle changes. The results were published online in JAMA Pediatrics. 

"An individual is two to eight times more likely to be obese if family members are themselves. Note that if each gene taken individually has only a small role in body mass and composition, the contribution of these genes becomes significant when they interact with external factors such as energy imbalance, ”notes Inserm. Looking ahead, new research needs to determine whether other genes unrelated to obesity may also affect weight loss.