Open Question: What is the best way to lose weight?

So i have been feeling rather unconfident lately, and i believe it is because of my weight. Im 16 and i am 5' 3, so know it may be normal, but i have never been to the point where i have been over weight. i feel like i have been gaining weight and i remember last year, i was alot skinnier than i am now. I had a flatter stomach and everything. I am usually athletic and i watch what i eat most of the time. Now, i feel like my waist has gotten alot bigger and my theighs seem bigger too. My arms seem thicker and it all makes me look over weight. So i have been trying situps and other things to try and slim me down a little, but nothing seems to be working. If it is weight that i am gaining, i need a way to help slim me up, and keep it off. i was thinking about drinking more water and eating less food through out the day, but i dont want to completely starve myself. Please if you have any suggestions, let me know. I highly appreciate it. Thank you