OBJECTIVE: There is evidence showing the effect of hypocaloric diet and increasing physical activity on weight loss. However, the effect of these factors on body composition and functional capacity remains unclear. Also, it is not clear which type of exercise (aerobic, resistance) has effective health benefits for men who are overweight. The aim of this study is to investigate whether a 12-week combined exercise or walking intervention combined with a hypocaloric diet provides improvements in body composition and functional capacity of men who are overweight compared to those who do not exercise. METHODS: 60 healthy adult men who are overweight were randomized and divided into 3 groups: 1: Hypocaloric Diet + Combined Exercise; 2: Hypocaloric Diet + Walking; 3: Hypocaloric Diet. The exercise groups were trained for 12 wk, 3 days a week and 60 min (60 min\3 days\12 wk). Body composition was determined with Bioelectrical Impedance Analysis (BIA) device, strength parameters with MicroFet 2, functional capacity with 6-min walking test. RESULTS: Improvement was observed in all groups at the end of 12 wk. The greatest improvement was in the combined exercise group. While the values of the combined exercise group increased in Skeletal Muscle Mass, there was a decline in the walking and non-exercising group. Basal Metabolism was maintained in combined exercise, but a decrease occurred in the non-exercising group. Muscle force increased in combined exercise; however, it was maintained in the legs in the walking group. Cardiorespiratory fitness was at best level in walking group, but there was no difference between combined exercise. CONCLUSIONS: As a result, a hypocaloric diet without an exercise prescription is sufficient to lose weight in the short term (12 wk) at a certain level. But exercise is more important for body composition, weight management and functional capacity. Long-term and in-depth studies should be conducted to interpret the results better.