Physical and psychological consequences of weight gain.

Obesity and overweight are clearly associated with many serious conditions, including type II diabetes mellitus, hypertension, and coronary heart disease. Excess weight also increases the risk of death. Recent evidence suggests that weight gain itself, even if persons remain within the "normal" weight range, also increases the risk of medical illnesses and premature death. Persons who gain 5.0 to 7.9 kg (11 to 17.3 lb) as adults are 1.9 times more likely to develop type II diabetes mellitus and 1.25 times more likely to develop coronary heart disease than those who lose weight or maintain a stable weight after age 18 years. Gaining 11 to 20 kg (24.2 to 44 lb) or more in adulthood increases the risk of ischemic stroke 1.69 to 2.52 times. The relationship between weight gain and breast cancer has been difficult to study, primarily because postmenopausal hormone replacement therapy can mask the effect of weight gain on cancer risk. Accordingly, weight gain in adulthood has been associated with an increased risk of breast cancer only among women who have never used hormone replacement therapy. In addition to its adverse effects on disease outcomes, weight gain also impairs physical functioning, reduces quality of life, and is associated with poor mental health. These psychological and mental health consequences of weight gain can become an added burden for patients with schizophrenia and other mental disorders.