Central Physiological Determinants
of Eating Behavior and Body Weight
SARAH F. LEIBOWITZ
Nutritional and appetite disorders occur in epidemic proportions. Obesity and diabetes affect over 30% of our population, while eating disorders occur in up to 3% of adolescents and young adults. Disturbed eating patterns are a primary symptom of numerous psychiatric disorders, and loss of appetite and cachexia, during illness or in the elderly, preclude proper medical treatment for restoring good health or preserving life. Increased understanding of the systems of the body and brain related to energy and nutrient balance may help us treat and prevent these common problems.
Researchers in neurobiology have used an integrative, interdisciplinary approach to study the multiple determinants of eating behavior, energy balance, and body weight. These include such diverse signals as (1) simple nutrients in the blood, including glucose, fatty acids, triglycerides, or amino acids; (2) classical neurotransmitter molecules for rapid, short-term communication; (3) larger neuropeptides for slower, more long-term action; and (4) circulating hormones for both neuromodulatory and metabolic processes. These signals derive from different peripheral organs, in particular, the adrenals, liver, pancreas, and gastrointestinal tract, and also from different areas of the central nervous system, from the hindbrain to the forebrain. Moreover, they are dynamic in nature, shifting across the daily cycle, developmental stages, the female estrous cycle, and seasonal periods.
In the periphery, in both animals and humans, a variety of substances are believed to be involved, in the complex process of integrating physiological and behavioral systems