How does my friend stay so skinny?

many people are gifted with a fast metabolism. problem is over the years it slows down. so her eating habits aren't going to be any different they are today then 15 years from now. so while you are watching what you eat. she is going to be eating like a pig at age 30 and is going to be extremely fat. if you keep a healthy life style at age 18 you will hopefully drag it out for the next couple years. and be healthy and when you see her at your high school reunion she is going to look alot different.