All of us teenagers go through this phase at one time or the other! It's not easy is it? Losing tummy weight has been very difficult for me, but I managed to do it. It took me a while to get used to the restrictive diet program, but believe me it was well worth it. I've lost 6 kilos in three months and I feel so much fitter. I suggest that you work towards achieving your goals right away. I went to a fitness center and they helped me a lot. They will design a good exercise pattern for you.