set point theory
A theory that postulates that body weight is regulated around a given set point using a homeostatic mechanism similar to that which regulates temperature. Preliminary studies indicate that people who lose weight through semi-starvation or gain weight by overeating return to their normal body weight quickly when they revert to normal eating patterns. It has been suggested that the body has the ability to balance caloric intake and expenditure to within plus or minus 10–15 kcal day−1. It appears that the body attempts to maintain its normal weight when overfeeding or underfed by changing the three components of expenditure (see resting metabolic rate, thermic effect of food, thermic effect of activity). If the set point theory is correct, it explains why some athletes have great difficulty losing or gaining body weight for weight-classification sports, such as wrestling and horse riding.