BACKGROUND: Weight maintenance is less successful in black women than in white women after weight loss. OBJECTIVE: We compared objectively assessed total energy expenditure (TEE) with estimates of energy expenditure (EE) from self-reported physical activity (PA) in overweight black and white women before and after weight loss. We also compared those values with values in never-overweight control subjects. DESIGN: A total of 20 white and 21 black premenopausal women were evaluated while overweight and weight reduced; 20 white and 14 black control subjects (matched with women in the weight-reduced state) were evaluated once. Weight loss of >/=10 kg was achieved by energy restriction in the overweight subjects. The evaluations were as follows: body composition (dual-energy X-ray absorptiometry), free-living TEE (doubly labeled water), Tecumseh Occupational Activity Questionnaire, Minnesota Leisure Time PA Questionnaire, and Baecke Activity Questionnaire. RESULTS: Questionnaire estimates of TEE were overestimated when compared with TEE (P < 0.001). Overweight women overestimated TEE 49% more than did never-overweight control subjects. After weight loss, white women reduced overestimation of EE 48% (P < 0.05), so that their overestimation of EE was not different from that of black and white control subjects. Black women overestimated to the same extent both before and after weight loss. CONCLUSIONS: Premenopausal women overestimate PA estimates on questionnaires. Overestimation of PA in weight-reduced black women is greater than in weight-reduced white women and never-overweight black and white women.