Short-term low-carbohydrate diet decreases body weight and fat mass but not muscle strength in children and young people with type 1 diabetes

Aims We investigated whether a short period of tightly controlled low-carbohydrate diet (LCD) leads to a change in body weight, body composition, and muscle strength in children and young people with diabetes (CYPwD). Methods Thirty-five CYPwD were recruited into this randomized controlled cross-over study (20 female; age 14.5 ± 2.9 years). The interventions were five and five weeks of ready-made food box deliveries of isocaloric diets in random order: either LCD (94.5 ± 4.7 g/day) or recommended carbohydrate diet (RCD) (191 ± 19.2 g/day). The outcomes were body weight and body mass index (BMI) standard deviation scores (SDS), body fat percentage assessed by bioimpedance and muscle strength assessed by jumping mechanography at the end of each dietary intervention. The Welch two-sample t-tests were used to determine the difference in outcomes. Results At the end of the LCD period, the participants had significantly lower body weight and BMI SDS than at the end of the RCD period (61.7 kg vs. 62.6 kg, P < 0.001, and 22.3 kg/m 2 vs. 22.7 kg/m 2 , P < 0.001) and (0.84 SD vs. 0.94 SD, P < 0.001, and 0.81 SD vs. 0.91 SD, P < 0.001). The body fat percentage was lower at the end of the LCD period (24.5% vs. 25.3%, P = 0.001). Dynamic muscle functions did not differ significantly at the end of the intervention periods. Conclusions We demonstrated that a short-term low-carbohydrate diet is able to decrease body weight, BMI, and decrease the percentage of body fat in CYPwD without negatively affecting their muscle function.