Hello Dear. Testosterone levels does go down due to ageing. But it s natural process. But it has got very little to do with increase of belly fat. Belly fat can come even in youth, if you are physically inactive. Main thing is that regular exercise at least half an hour per day is must. Exercises particularly focussed on abs can reduce belly fat. Even diet control is very important. Small meals at frequent intervals is the main motto. Many a times people eat very little for breakfast, then bit for lunch, then at night they are very hungry and do binge eating. This is very bad. Eat well for breakfast. And very little for dinner. Avoid oily food and high calorie food. Preferably be a vegetarian. Lead a stress free life as much as possible. These things will help reduce belly fat. Hope your question is answered. Feel free to contact me for any more queries. With warm regards Dr Sanjay Kini