Association of weight control behaviors with body mass index and weight-based self-evaluation.

Objective:: To determine the frequency of weight control behaviors (WCBs) and their correlation with body mass index (BMI) and weight-based self-evaluation.

Methods:: Data were collected by the Brazilian Internet Study on Temperament and Psychopathology (BRAINSTEP) from 27,501 volunteers (30.4% men, mean age 28.9±8.7 years).

Results:: The most prevalent WCBs for men and women were exhaustive physical exercise and prolonged fasting, respectively. Frequent exhaustive physical exercise was the only behavior more often adopted by men. BMI was positively associated with WCBs, which were very frequent in obese subjects. About 15% of normal-weight women reported using diuretics and laxatives, and 12.2% reported vomiting as a WCB at least occasionally. Among subjects who regarded body weight highly in their self-evaluation, there was a strong positive association with all WCBs, at similar degrees, in both genders. Compared to those who never base their intrinsic personal value on body weight, those who frequently base intrinsic value on body weight were at 25-30 times higher risk of inducing vomiting.

Conclusion:: The prevalence of participants adopting WCBs was high, especially in women and obese subjects. Weight-based self-evaluation was more strongly associated with WCBs than BMI.