OBJECTIVE: To evaluate the effect of weight and body composition changes on waist measurement of severely obese women receiving a low-carbohydrate diet for a short-term. METHODS: Nineteen severely obese women divided into an intervention and a control group received a low-carbohydrate diet and a conventional diet, respectively, both with 1,200kcal, for seven days. Anthropometric measurements such as weight, body mass index, arm circumference, waist circumference (at the navel), two proposed measurements of waist circumference (waist circumference 1, 10cm above the navel; and waist circumference 2, 20cm above the navel), hip circumference; and body composition (lean mass and fat mass) were performed at baseline and end of the study. RESULTS: There was significant reduction of all variables in the intervention group (p<0.01), but the control group had no change in waist circumference (p=0.06) and hip circumference (p=0.36). Patients of the intervention group presented greater weight loss (4.4kg, p<0.01) and reduction of body mass index, waist circumference, waist circumference 1, waist circumference 2 (p<0.01), and fat mass (p=0.04) than the control group. CONCLUSION: The weight loss and body composition changes were greater in the low-carbohydrate group than in the conventional-diet group, and they had a greater impact on waist measurements. The proposed measurements (waist circumference 1 and waist circumference 2) were sensitive to weight reduction in both groups.