Low-carbohydrate (low & high-fat) versus high-carbohydrate low-fat diets in the treatment of obesity in adolescents

Aim: To compare the impact of low-carbohydrate diets of different fat content to high-carbohydrate low-fat diet on weight and metabolic parameters in obese adolescents. Methods: Fifty-five patients aged 12-18 years with a body mass index (BMI) above the 95th percentile were randomly allocated to one of three isoenergetic diet regimens. Anthropometric and metabolic measurements were taken after overnight fast, at baseline, after the 12-week intervention and after nine month of follow-up. Results: No significant differences were found among the groups in changes in BMI, BMI-percentile, fat percentage, or metabolic markers at the end of the intervention and at the end of follow-up. Insulin level and homeostasis model assessment (HOMA) level decreased significantly at both time points only in the two low carbohydrate diet groups. Conclusion: All diet regimens are associated with a significant reduction in BMI and improvement of some metabolic parameters in obese adolescents. Low-carbohydrate diets apparently have no advantage over high-carbohydrate low-fat diets. The significant drop in insulin level and HOMA in the low carbohydrate diet groups is noteworthy given the increasing frequency of type-2 diabetes as part of metabolic syndrome in children and youth. The impact of low carbohydrate diets in obese and insulin-resistant youth warrants further investigation.