Regulatory Feedback Mechanisms in Fat Gain and Eating Behavior

Regulatory feedback mechanisms should prevent excessive fat gain, but homeostatic and non-homeostatic factors can override these controls. Homeostatic controls are hunger-driven behaviors to meet energy needs, while non-homeostatic factors like habits and environmental influences can lead to overeating. The brain defends both lean and obese states against weight changes, indicating a change in the regulatory system. It's unclear why some individuals transition to defending a higher body fat level. Non-homeostatic overeating and elevated leptin levels may contribute to actively defending a higher body fat level. People with obesity show an inflammatory injury response in the hypothalamus that regulates body fatness, possibly triggered by passive overeating. Surroundings with calorie-dense foods, insufficient physical activity, lack of sleep, and poor stress regulation can also lead to passive overeating and the defense of a higher body fat level.