INTRODUCTION: Adolescent obesity requires effective and accessible intervention options and there is potential for intensive dietary interventions to be used as adjunctive therapy to behavioural weight management for some individuals.
METHODS: The Fast Track to Health study (HREC/17/SCHN/164; ACTRN12617001630303) was a multi-site 52-week RCT, conducted 2018 – 2023, comparing a very low energy diet followed by i) an intermittent energy restricted (IER) diet; and ii) a continuous energy restricted diet (CER), for adolescents (13-17years) with ≥1 obesity associated complication. Interventions were delivered as part of an intensive behavioural weight management intervention by a multidisciplinary team. Anthropometry, body composition and cardiometabolic health were assessed at baseline and 52weeks. Dyslipidaemia was defined as HDL <1.03mmol/L and/or triglycerides ≥1.7mmol/l, and elevated liver function tests (LFTs) as ALT and/or GGT ≥1.5 upper limit of 30U/L.
RESULTS: In total, 141 adolescents (70 female) were enrolled and 97 (48 female) completed the intervention. At 52 weeks, BMIz reduced by -0.23 [95%CI -0.37 to -0.22], BMI expressed as a percentage of 95th percentile reduced by -8.86 [95%CI -12.46 to -7.47] and Fat Mass Index reduced by -1.49 [95%CI -2.36 to -1.08]. There was no significant difference for weight or cardiometabolic outcomes between diet groups. The occurrence of dyslipidaemia was unchanged between baseline and 52 weeks (n=60 [43%] and n=37 [43%] respectively) and a small improvement in the occurrence of impaired LFTs (n=37 [27%] to n=15 [17.2%] respectively). There were no differences in change of dyslipidaemia or impaired LFTs between intervention groups.
CONCLUSION: These results suggest that both IER and CER, delivered as part of an intensive behavioural weight management program, are equally effective for improving weight and cardiometabolic outcomes for adolescents with obesity.