I'm overweight and I can say for sure: If you want to put on more weight, eat take away food. Chinese, KFC, Maccas, HJs. Full cream milk I've been told is good for "growth". Protein shakes as well. Is or could there be a medical reason you cant put on weight or is it high met? My friend cant put on weight because of her kidneys, she did explain but it went over my head. Maybe get checked out?