Background:
Intermittent fast diets in adults are as effective as continuous energy restriction. This is the first study to investigate the effectiveness and acceptability of an intermittent fast diet (IFD) in adolescents with obesity.
Methods:
During weeks 1-12, participants followed an IFD consisting of a Very Low Energy Diet (VLED) 3 days/week (500-600kcal/day) and a standard healthy diet 4 days/week. For weeks 13-26, participants were given a choice to continue with 1-3 days of VLED/week or follow a standard healthy diet. Outcomes measured at 0, 12 and 26 weeks were weight, fasting glucose, insulin sensitivity, lipids and diet acceptability.
Results:
30 participants, aged 12-17 years (mean [SD] 14.5yrs [1.4], female n=25) with a median BMI 34.9kg/m2 (range: 27.7-52.4), were recruited and to date, 19 have completed the 26 week protocol. The study will be complete in August 2017. Compared with baseline, both body weight and BMI were reduced at 12 weeks (mean [SD], n=20, -3.5kg [3.7], -1.4kg/m2 [1.3]) and 26 weeks (n=18, -2.1kg [7.9], -0.9 kg/m2 [2.6]). Fasting insulin (n=18, -26.2pmol/l) and triglycerides (n=16, -0.2mmol/L) were reduced at 12 and 26 weeks from baseline, respectively. The reduction in insulin was sustained to 26 weeks in those who maintained or continued to lose weight (n=10, -38.6pmol/l). At 12 weeks, all participants chose to continue with the IFD with 2 days/week (n=11) or 3 days/week (n=10) of VLED. Adolescents found the IFD acceptable, rating it as easy (mean [SD] n=15, +2.1 [1.2]) and pleasant (mean [SD] n=15, +1.7 [1.2]) on a Likert scale from -4 to +4.
Conclusion:
Intermittent fast diets may be an effective and acceptable dietary intervention in adolescents with obesity. A randomised controlled trial is required to compare IFD with continuous energy restriction.
This study was funded by the Foundation for Children and Heart Foundation of Australia Vanguard Grant.