Effects of diets with different macronutrient distribution on body composition during caloric restriction followed by ad libitum feeding in aged mice

Weight loss and body composition improvements pursued by overweight persons and athletes can be achieved with caloric restriction (CR) using different dietary macronutrient distribution (Ge et al. 2020, Aragon et al. 2017). However, a post-diet period is less studied and it is not clear how selected dietary macronutrient distribution sustains these achievements particularly when return to ad libitum feeding (Muhammad et al. 2017). The aim of the study was to examine this issue using the mouse model. 18-month-old naturally overweight males of the C57BL/6J mouse strain were examined. They were matched by body mass into three groups (n = 23 each) and subjected to 30% CR for 4 weeks with either low-fat (LFD; 20, 60, 20% of total kcal for protein, carbohydrate, fat, respectively), low-carbohydrate diet (LCD; 20, 20, 60%) or high-protein (HPD; 35, 35, 30%) followed by 4 weeks of refeeding period (RFD) on the same diets ad libitum. 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 or RFD. Eleven mice on ad libitum chow diet served as controls throughout the experiment. CR resulted in more than 30% weight loss with no differences between diet groups (P > 0.05). Majority of it was contributed to body fat loss while muscle mass loss was much less but still significant compared to controls (P 0.05). However, LCD overshot controls and both other diet groups in body and fat mass by 18-21% and 100-118%, respectively (P < 0.001). In conclusion, the low-carb-high-fat diet leads to similar improvements in body composition during CR compared to other types of diets but much greater body fat recovery and overshoot during ad libitum post-diet period in aged mice