It matters as much of what you eat as how much you eat. And a lot of people, especially at your age, have freaky high metabolisms so comparing yourself to what your friends do is not going to work. I'm still waiting for one of my friends eating and exercise habits to catch up with him and he turned 33 today. As others have said though check into body mass index and use it as a guide, much better than considering weight as it considered muscle tone / fat percentages etc. A lot of people today are actually "skinny fat" where the scale says they are healthy but BMIs are not.
"Unless someone like you cares a whole awful lot, nothing is going to get better. Its not." Dr. Seuss
"Use peaceful means where they are appropriate; but where they are not appropriate, do not hesitate to resort to more forceful - Thupten Gyatso (the Dalai Lama, 1932)
"It is not the will to win that matters - everyone has that. It's the will to prepare to win that matters" Coach Paul 'Bear' Bryant.
"The ink of scholars is more precious than the blood of martyrs" - Muhammed