I usually do these when I'm being bullied because I'm fat.
1. Work on my attitude. Any fact facing us is not as important as our attitude toward it, for that determines our success. No one can make you feel inferior without your consent. Just show "I don't care" attitude. People always tend to do more when you react more. When you stop giving them a shit, they will be disappointed and never again do it.
2. Work on my wardrobe. We can change our body appearance to a maximum of 30% by wearing appropriate clothes that will show you as an averagely built person. Check online, they have some pretty good ideas for that.
3. Work on my nutrition or think about the people like ME who wants to be skinny! lucky that you are! :)
The best way to deal with this is to ignore anyone who is bullying and mocking you. Exchanging bitter words with people who are trying to pin you down can cause ravaged reactions which may worsen the situation. Try to avoid being in a company of such people and instead, find friends who appreciate and like you for who you are. If the situation gets worse, you can report those bullying you to the teacher.
Stay strong and don't think about how you look on the outside, but about how you feel on the inside. It's important to know that you are doing the right thing, most importantly, believe in yourself (; you can get through it. (Believe it or not, they are just jelly)
I never had any experience of being bullied, but it is true that words are more painful than Acting. But for as long as they are not hurting you physically. It is just okay I guess.. Smile at them and feel pretty.