What are the best ways to lose stubborn belly fat?

I am really wanting to lose my belly fat. I drink bottled water everyday, sometimes even 10 bottles of water a day. I walk on a treadmill for about 1-2 hours and do 100 sit ups everyday. And I have been trying to eat only 1 meal a day. But I don’t seem to be losing the belly fat like I want, and I have been trying this for 2 months. Anybody got any good ideas or suggestions?