Sample size estimation
The estimation of the sample size was based on the rate of weight reduction with non-pharmacological treatment (diet and physical activity) is approximately 15% (p1) and it is assumed that we want to achieve a success rate of 35% (p2) in the experimental group (patients with Obex® treatment), i.e. we aim to detect a difference of 20% between the two treatments, with a Type I error = 0.05 and a Type II error = 0.2. Under the above assumptions, a total of 146 patients would need to be included, 73 in each treatment group. Assuming a probable subject loss of 10.0% during the trial, a total of 160 patients (80 in each treatment group) would then need to be recruited to ensure adequate power.