^ disagree with both of the above posts.
First of all, exercise helps tone your body. If you do weight bearing exercises to tone your gluteus maximus you will tone and gain muscle there making it appear fuller.
Whether you lose, gain or maintain your weight while exercising really depends on your diet and not exercise alone.
Secondly, eating sugar is the biggest mistake you can make. Not only is it unhealthy for you but it will also make you gain weight in areas that you do not wish to gain weight.
My suggestion : start weight training. doing exercises such as squats and lunges are a few of the many things you can do to make your glutes look fuller.
Ditto! :)