BACKGROUND: The Russian Federation is among the top ten countries in terms of obesity prevalence among adults. AIM: To identify the endogenous (biological factors such as age and FTO genotype) and exogenous (diet and physical activity level) factors that influence body fat accumulation and distribution among a group of women and men from Moscow. MATERIAL AND METHODS: A total of 464 volunteers, consisting of 231 women and 233 men aged between 18 and 60 years, from Moscow took part in a single-center, cross-sectional, observational study. The program involved measuring body height, weight, body and limb girths, as well as conducting caliperometry, bioimpedance analysis, and administering questionnaires. Indices of body fat distribution were calculated. Additionally, differences in genotype, specifically the rs9939609 TA variant in the FTO gene, were also determined. RESULTS: Maintaining a vegetarian diet for at least three years was associated with lower fat and fat-free mass, but not with abdominal fat in both men and women. Engaging in regular physical activity had the most significant impact on abdominal fat in both genders. Furthermore, participating in amateur or professional sports activities for a minimum of 180 minutes per week was associated with lower overall body fat. We found no association between the FTO rs9939609 gene and fat accumulation or distribution, regardless of diet and physical activity levels. CONCLUSION: The results suggest that vegetarian diet and regular physical activity are likely to be the most effective total and abdominal fat loss strategy for male and female adult residents of Moscow.