Sample size calculation
The sample size calculation was done by G*Power 3.1.9.2 (Universitat Kiel, Germany). We performed a pilot study on five cases in each group. The mean ± SD of leptin level after 2 weeks (the primary outcome) was 1.42 ± 0.148 ng/ml in the control group and 1.74 ± 0.52 in the study group. Four cases were added to each group to overcome dropout. We needed 35 cases in each group to achieve 90% power of the study with a 0.83 effect size and 0.05 α error.The CONSORT 2010 checklist is included in the supplementary files (supplementary file 1).