Weight gain occurs after onset of bipolar illness in overweight bipolar patients.

BACKGROUND: Bipolar patients appear to have a risk of weight gain and obesity higher than the general population. This has traditionally been attributed to medication and disease variables, but there have not been any studies that have investigated this directly. METHODS: We examined 32 consecutive bipolar subjects and 32 matched controls for weight, BMI, fat content, and historic weight at age 18. RESULTS: Bipolar patients were heavier (193.1 +/- 55.6 vs. 165.6 +/- 37.8 lbs., P = 0.03), with greater BMI (30.3 +/- 8.8 vs. 24.3 +/- 4.0, P = 0.001), and higher fat content (33.3 +/- 9.9 vs. 19.1 +/- 9.9%, P < 0.0001) than psychiatrically well controls. A larger fraction of bipolar subjects were obese (BMI > 30, 50% vs. 9.7%, z = 3.88, P < 0.01). However, weight at age 18 was not statistically different (143.0 +/- 35.8 for bipolar subjects vs. 152.8 +/- 42.7 lbs., P = 0.3). CONCLUSIONS: This is the first controlled study examining weight gain in bipolar illness and the first demonstration that premorbid weight is in the normal range for bipolar subjects. Subsequent weight gain is probably related to illness and treatment variables.