The aim of this randomized, double-blind, parallel-group, placebo-controlled trial is to evaluate whether molecular hydrogen supplementation enhances the effectiveness of weight loss retreat for overweight and obese adolescents. Weight loss retreat is indicated for participants based on diagnosis and recommendation of a pediatrician. During the 4-week retreat, participants follow a prescribed standardized intervention consisting of reduction diet and physical activity. The total planned number of participants is 60. Participants are randomly divided into two balanced groups, with one group receiving molecular hydrogen in the form of hydrogen-rich water and the other receiving a placebo water. The daily amount of water given (hydrogen-rich or placebo) is 1.5 L. Hydrogen-rich water is packaged in specially designed aluminum containers to minimize hydrogen leakage and ensure long-term stability with a dissolved hydrogen concentration of 1.2-1.6 ppm. Participants are unable to distinguish hydrogen-rich water from the placebo because molecular hydrogen is colorless, odorless, and tasteless. Participants monitor their physical activity, sleep, and sedentary behavior one week before to retreat and undergo baseline diagnostics (including blood sampling), three weekly interim diagnostics during retreat, and final diagnostics (including blood sampling) after four weeks. If participants are available, two follow-up diagnostics are conducted six weeks and six months after the retreat and include seven-day monitoring of physical activity, sleep, and sedentary behavior. Statistical analysis is performed at a significance level of α = 0.05 and the data is evaluated using analysis of variance. In cases of non-normality, data transformations or non-parametric alternatives are used.
