Context: A higher protein to carbohydrate ratio in the diet may potentiate weight loss, improve body composition and cardiometabolic risk, including glucose homeostasis.
Objective: To determine the efficacy of two structured lifestyle interventions, differing in dietary protein and carbohydrate composition, on insulin sensitivity and body composition. We hypothesized that a moderate-carbohydrate, increased-protein diet would be more effective in improving outcome measures in obese, insulin resistant adolescents.
Design: Randomised control trial, known as RESIST, in two hospitals in Sydney, Australia.
Participants: Overweight or obese 10 to 17 year olds with either pre-diabetes and/or clinical features of insulin resistance.¹
Intervention: At baseline adolescents were prescribed metformin and randomised to an energy restricted diet, which was either high-carbohydrate or moderate-carbohydrate with increased-protein. The intervention included regular contact with the dietician and a supervised physical activity program.
Outcomes: Insulin sensitivity index measured by an oral glucose tolerance test and body composition measured by dual-energy x-ray absorptiometry at 12 months.
Results: 77% of the 111 adolescents completed the intervention. Body mass index expressed as a percentage of the 95th percentile decreased by 6.8% [95%CI:-8.8 to -4.9], ISI increased by 0.23 [95%CI: 0.06 to 0.39] and total fat decreased by 2.4% [95%CI:-3.4 to -1.3]. There were no significant differences in outcomes between diet groups at any time point.
Conclusion: When treated with metformin and an exercise program, a structured, reduced energy diet, which is either high-carbohydrate or moderate-carbohydrate with increased-protein, can achieve clinically significant improvements in overweight and obese adolescents at risk of type 2 diabetes.