Isocaloric weight-loss diets with contrasting carbohydrate and fat content led to similar body mass and composition changes in elderly mice

Introduction. Caloric restriction (CR) is essential in obesity treatment and weight-making practices in some sports. It is still controversial about the role of carbohydrate and fat content in weight-loss diets on body mass and composition especially in elderly population which seems to be more prone to glucose intolerance. Our goal is to address this issue using the mouse model. Methods. 18-month-old and naturally overweight males of the C57BL/6J mouse strain were matched by body mass into two groups (n = 6 each) and then subjected to 30% CR for 4 weeks with either low-fat (LFD; 20 and 60% of total kcal for fat and carbohydrate, respectively) or low-carbohydrate diet (LCD; 60 and 20%). Body mass was monitored daily and hindlimb muscles as well as major body fat sites were dissected and precisely weighted at the end of CR. Results. The dynamics of the daily changes in body mass was similar between LFD and LCD at each time point during CR (P > 0.05). Overall, LFD and LCD groups decreased their body mass by 27.5 ± 3.0 and 25.6 ± 2.6%, respectively. There were no differences between groups in mass of any single muscle or fat site at the end of CR. Combined muscle mass was 391.7 ± 34.5 and 406.3 ± 20.4 mg and combined fat mass was 1137.2 ± 660.3 and 1170.2 ± 344.2 mg for LFD and LCD (P > 0.05). Conclusions. Dietary carbohydrate and fat content do not affect body mass and composition improvements in elderly mice during isocaloric food restriction