Physiological regulation of weight

The normal individual maintains its body weight in a predetermined level of stability quite remarkable, given how much they vary daily calorie intake and activity level. Given the physiological importance conserve energy reserves is difficult to lose weight and keep it off voluntarily.

Appetite and metabolism are regulated by a complicated network of neural and hormonal factors. Hypothalamic centers for hunger and satiety are essential in these phenomena.

Some neuropeptides such as corticotropin-releasing hormone (corticotropin-releasing hormone, CRH), the melanocyte-stimulating hormone alpha (α-melanocyte stimulating hormone, α-MSH), and the transcript related to cocaine and amphetamines (cocaine and amphetamine-related transcript, CART) cause anorexia by acting on the central nervous system (CNS) in the satiety centers.

Gastrointestinal peptides ghrelin, glucagon, somatostatin and cholecystokinin are those which cause satiety and reduces food intake. Hypoglycemia suppresses the action of insulin, which lowers glucose utilization and inhibits the action of the satiety center.

Weight loss Occurs
when energy intake exceeds the calories available for this purpose. In most individuals, about half of the energy from food is used as basic functions such as keeping the body temperature. In a 70 kg weight, basal metabolism consumes about 1 800 kcal / day.

About 40% of calories consumed in exercise, although athletes can use more than 50% when performed in a marked degree. About 10% of caloric intake is used for dietary thermogenesis, a process in which energy is consumed in the digestion, absorption and metabolism of food.

The mechanisms of weight loss

The lowest food intake, malabsorption, loss of calories and increasing energy needs . The changes in body weight may be due to the changes in tissue mass or fluid volume contained in the body. In general, a shortfall of 3 500 kcal corresponds to a loss of 0.45 kg of body fat, but must also take into account water (1 kg / L) to be won or lost. Weight loss that lasts weeks to months usually means a loss of tissue mass.