Abstract
BACKGROUND: The first-line strategy for the treatment of obesity is weight loss (WL) through decreasing calorie intake. However, a diet that is capable of attenuating fat free mass decline following WL is preferred. Furthermore, it is required to choose proper measurements and appropriate obesity-assessment indices to monitor weight and body composition during WL program. METHODS: A total of 68 adults with overweight and/or obesity underwent a WL program (rapid and slow WL). Dependent variables include: weight, resting metabolic rate (RMR), body composition, and related measurements such as waist circumference (WC), waist to height ratio (WHtR), body adiposity index (BAI), a body shape index (ABSI), fat mass to lean body mass (FM/LBM), and percentage body fat (PBF). RESULTS: Obesity measurements decreased in both groups (all P < 0.05) while LBM and RMR decreased more in the rapid WL group (P < 0.05). After age and sex adjustment, a robust correlation was observed between FM/LBM and PBF (r = 0.918), LBM% and PBF (r = -0.949), LBM% and FM/LBM (r = -0.904), WHtR and WC (r = 0.986), and BAI% and HC (r = 0.986) (P < 0.001 for all correlations). FM has the highest correlation with WHtR among other indices (r = 0.706). CONCLUSIONS: Compared to fast WL, our data support that slow and gradual WL is more effective to improve body composition and obesity-assessment indices. The robust relationship was observed between FM and WHtR, among other indices such as BMI or ABSI. Therefore, in order to evaluate FM, where the FM is not measurable, the WHtR might be the reasonable index.