High-Fat Foods Fuel Weight Gain By Tweaking Hunger Hormones

Researchers with Baylor College of Medicine have published a new study revealing the potentially damaging effects of high-fat diets on body weight, warning that eating these food products may disrupt appetite and fuel overeating. Key to the findings is a hormone called gastric inhibitory polypeptide (GIP) and its effect on leptin, the hormone that reduces hunger.

Leptin is known to play a role in hunger and one's tendency to overeat, but the full picture has remained unclear. Leptin is secreted by fat cells and it works by inhibiting hunger — meaning that when leptin is high, hunger is low. There's an exception, however: obese individuals secrete too much leptin due to excess body fat, resulting in leptin resistance.

Leptin resistance is essentially a lack of response to leptin signals, leading to a persistent sense of hunger that drives overeating and weight gain, pulling people into a cycle of obesity that can be difficult to escape. The new study out of Baylor sheds light on why this happens, linking it to a hormone produced in the gut called GIP.

Researchers found that mice who ate a high-fat diet experienced increased levels of GIP. When too much GIP is present in the blood, it travels to the brain and inhibits leptin. As a consequence of interfering with leptin, the individual (or, in this case, mice) doesn't feel satiated after eating, causing them to overeat and gain weight.

The study found that by inhibiting GIP's ability to interact with the brain, mice were responsive to leptin, experienced decreased appetite after eating, and didn't overeat. This led to weight loss in the mice, highlighting a potential future treatment pathway for addressing obesity in humans. Though the research focused on mice, it indicates that decreasing fatty foods and increasing fat-free foods like fruit and leafy vegetables in one's diet may help overeaters feel satiated.