on diet

I have a friend who is always dieting all the time. But last night while taking on our lunch break she was eating a lot of food. We were all eating a lot last night and I was very full. I said that I thought she was on diet? She said she was depressed and could not resist the food. I think she needs to take an appetite suppressants to help her with her diet. I am not sure if it is right for her but maybe she should try and if it works for her.