Obesity is a chronic disease associated with chronic inflammation, insulin resistance, dyslipidemia, oxidative stress and increased risk for type 2 diabetes, cardiovascular disease, stroke and multiple cancer types. Oxidative stress can lead to base lesions of DNA which could be detected with alkine comet assay and its version with use of formamidopyrimidine DNA glycosylase-endonuclease enzyme in fresh or frozen small volume samples. Dietary caloric restriction has beneficial effects on insulin sensitivity, inflammation, oxidative stress and DNA repair. Very low calorie diet (VLCD) data are scarce, especially on the changing levels of DNA damage.This study will assess the effect of a three-week VLCD used in Special Hospital for extended treatment of Duga Resa in individuals with BMI ≥ 35kg/m2 on the level of primary and oxidative DNA damage as well as body composition and biochemical parameters.