Overweight and Obesity: When Genes Make You Fat

Our genes influence our feeling of satiety, fat metabolism, and fat distribution. So there is a genetic predisposition to overweight and obesity.

Getting obese or staying lean depends on how much you eat and exercise. But the genes also determine how difficult it is to maintain weight. They provide the blueprints for all substances in our body and are involved in the production of hormones and proteins that determine our eating habits and metabolism.

Leptin and MC4R determine satiety

If the blueprint of the satiety hormone leptin or the leptin receptor (LEPR) is defective, there is no feeling of satiety and the person concerned is constantly at risk of eating too much.

The melanocortin-4 receptor gene (MC4R) also influences appetite: certain variants of this gene mean that their carriers never think about eating, so they eat little and stay thin. However, other variants mean that the desire to eat is omnipresent. The carriers of these gene variants never feel full and therefore often eat far too much.

FTO regulates fat metabolism

The most well-known gene that influences fat metabolism is called FTO (“Fat mass and obesity-associated gene”). It regulates whether we store or burn fat. Humans have three types of fat cells: white fat cells store fat, while brown fat cells burn fat while releasing heat. Adults have very few brown fat cells.

The third type is decisive: the beige fat cells. You can both burn and store fat. In people with certain variants of the FTO gene, the beige fat cells can only store fat and not burn it – the result is obesity.

Fat distribution is dependent on genes

Scientists have already identified more than 40 gene segments that determine how fat is distributed in the body. So there is a genetic predisposition to obesity. In total, the researchers already know 2.1 million gene variants in around 100 sections of the genome that have an impact on weight.

Together, the gene variations can account for up to five points in the body mass index (BMI) – and that often means the difference between normal weight, overweight and obese people. On the scales, however, even the strongest genes only weigh up to two kilograms.

Intermittent fasting and exercise: behavioral change affects genes

The influence of the hereditary factors ensures a different starting position. However, our behavior decides whether the genes are switched on or off: so-called epigenetic mechanisms cause, for example, a gene that has been muted by high-calorie nutrition to be activated by intermittent fasting, calorie-reduced food or sport, so that the fat metabolism or sugar metabolism suddenly works better again and with weight loss supported.

Tailor-made therapy is the goal

The reasons for obesity vary from person to person. And the ideal strategy for losing weight is just as different. Obesity centers rely on three building blocks in the fight against obesity:

  • movement
  • nutritional advice
  • bariatric surgeries, such as gastric bypass

Which method is most effective individually depends largely on the genes of those affected.

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