Effect of caloric restriction with protein supplementation on weight, adipose mass, and muscle mass in professional male soccer players: a controlled randomized trial

Background Achieving optimal body composition can be advantageous for athletes in terms of competitive performance. To date, there is no research examining the effects of caloric restriction (CR) on body composition in male professional soccer players. Purpose This study aims to investigate the impact of 6 weeks of CR with protein supplementation on body composition and the maintenance of changes after stopping CR for the next 6 weeks. Methods The study was a controlled, randomized, parallel-group, experiment involving 28 participants. The experimental group received a CR diet (2650 kcal/d) and the control group received a normal caloric (NC) diet (3500 kcal/d). The intervention lasted for 6 weeks, followed by 6 weeks without intervention and provision of ad libitum diet in both groups. Body composition was assessed using anthropometric measurements. Results The study participants were aged 27.6 ± 4.4 years on average. After 6 weeks, the CR group showed a significant reduction in body weight compared with the NC group (− 0.33 kg for CR vs. −0.08 kg for NC; p  < 0.05). Both groups experienced a reduction in adipose mass after 6 weeks ( p  > 0.05), but only the CR group continued to decrease body fat after stopping CR ( p  < 0.05). Throughout the study, there was an increase in muscle mass, and no significant difference was observed between the two groups ( p  > 0.05). Conclusions CR with protein supplementation improves body composition in male professional soccer players by reducing weight, promoting fat loss, and enhancing muscle mass.