<qa>  What is the effect of H2 on body composition, hormonal status, and mitochondrial function inMolecular hydrogen H2 effectively tackles obesity-related disorders in animal models yet no studies so far investigated the effectiveness of H2 for improving biomarkers of obesity in humans. In this double blind, placebo-controlled, crossover pilot trial, the investigators will evaluate the effects of H2 intervention on body composition, hormonal status, and mitochondrial function in middle age overweight women, with hydrogen administered orally for 4 weeks. 