Researchers find brain perceives weight loss as a survival risk

Researchers at the University of Copenhagen have found that the brain perceives weight loss as a threat to survival and actively works to restore the body to its previous mass. The study, published in the journal "Science Advances," identifies the biological drivers behind weight regain following diets or the discontinuation of weight-loss medications. The analysis revealed that reducing body mass triggers a cascade of protective responses. The body increases levels of ghrelin-the hormone responsible for hunger-which intensifies cravings for calorie-dense fatty and sugary foods. Simultaneously, the basal energy expenditure drops as the body begins to conserve calories during physical movement. This process is driven by a biological "memory" in the brain that aims to return the organism to its habitual weight set point. This mechanism explains the effects of GLP-1 receptor agonists (such as Ozempic). While these drugs artificially suppress appetite signals, the body's biochemistry reverts to its original state once the medication is stopped, leading to the restoration of lost weight.