text: your only 14 . you are still developing. eat healthy foods rich in protein. eggs are a good food for that. eat calcium such as cheese , drink milk. any dairy products . if you can exercise all your body. run , ride a bike. swim that is excellent for building the muscles and stamina .Your body metabolism may keep your Skinner /slim all your life. you will still grow for a few more  years till you are 21.If you are meant to be thin you are lucky.look at your family. If any one or several are slim then you may be also.