How can I lose some weight before school starts?

Ok, anorexia is a disease - you don’t want to go there.

Besides, given your modest goal of losing only 5-10 pounds, with eleven days, it should be easy for you, provided you can do the following:

1. stop eating sugar, drinking colas, etc. Diet OR regular.
2. drink water only, and if you must, drink some vegetable juice (V8, etc)
3. exercise for an hour a day, something cardio, that will burn the most calories for the session.
4. eat a balanced diet, stay away from fatty foods, eat vegetables, fruit, whole grains, and some protein. Don’t skip on any of the important food groups.

If you can stick to that, and eat exactly - no more, no less - your daily calorie needs for your age / height / and weight (should be about 1500 per day), then I can guarantee you’ll lose the weight you want. Yep, it’s hard, it’s not fun, and trust me - I’m no more a fan of eating vegatables than you are. But if you’re serious about weight loss, it is the only way to go that won’t ruin your health, appearance, or cause you other problems.