I am female, 18 years old, trying to lose weight. I am 5'10 and weigh about 164. I was very active, but in the last year, I stopped exercising as often, and didn't eat very well. I have been trying to lose weight by exercising strenuously for at least an hour each day, and by making sure I eat healthy food. This last week, my appetite has completely disappeared, and I have started gaining weight, despite the fact that I can hardly force myself to eat three meals a day. I don't know of anything I've done that might make my metabolism slow down like that. I thought exercise was supposed to boost your metabolism? Can anyone tell me what I might be doing wrong...?