Sample size
The sample size was estimated for the main outcome of the randomized clinical trial, child body mass index (BMI) for ages (17, 18), using WinPepi® software version 11.65, based on previously published studies on the subject. Considering a unit standard deviation of 1, the statistical power of 80%, and a significance level of 5% to detect a difference in BMI of 0.8 kg/m