if you're 14 you can lose weight much easier than someone who is done growing. eliminate all soft drinks, alcohol (if you even drink that is), fast food, and sugary stuff. eat a lot of meat, seafood, and vegetables. that's not saying don't treat yourself to a fatty burger here and there, though. some times you can't always eat a clean meal. also make water the only thing you drink. no tea, milk, or juice. try to drink at least 4 tall glasses of water a day.

if you're going to exercise try to get it done in the morning. this will kick-start your metabolism for the day and burn more fat. also try to eat 4-6 small meals a day. this will increase your metabolism because it will always be burning something off. if you're going to lift weights and do cardio, lift weights prior to your cardio. this way your heart rate will already be up and in 'fat-burn' mode. also don't lift weights every day...do it every other day at the least, so your muscles have time to grow back.

sleep is also important. get at least 6-8 hours a night.

good luck man.