High metabolisms do exist, but you're absolutely right that it's no excuse. What you just described are Ectomorphs. People with ectomorph body types are "hard gainers." They are skinny, usually with small chests and thin shoulders. I'd say I'm under this category. But since the summer started I've been on a program that's yielded results I'm liking, slow and steadily. Now I'm probably not as small as some people on this site, but the program I did would likely benefit anyone trying to gain weight. I was 135 at 5'8" the start of the summer. I'm about 144 pounds now. To do this I began eating more and going to the gym AT LEAST 3 times a week. "But wombraider, I do eat a lot!!!" No you don't. Or at least, not what you should be eating. I'm no nutrition expert, but protein gets you bigger. You need to be eating lots of chicken and beef, fish if you like it. Protein powder drinks are good too. I use basic whey protein powder and drink about 1 scoop and a half after a workout. Also, you need to be drinking lots and lots of water. Before I go to bed I would eat a turkey sandwich and 2 glasses of water as well, to hold me over while I slept. That's just a basic nutrition guide. As for working out: I haven't done ANY cardio at all, literally zero. All I do is big muscle group workouts. Bicep/tricep back/chest and abs. I don't do legs because I've been a soccer player and sprinter my whole life, my legs are already big enough to support me and not look goofy even if my upper body gets larger. Also keep your workouts short, just going and pushing weight for hours on end won't get you bigger. Any workout longer than 45 minutes and you're just burning calories you need to gain weight. I haven't even been that super dedicated to my workout program, I've just been eating more and more of the right stuff. TL;DR he's right you can gain weight; no excuses Eat more beef and chicken and protein shakes Workout no longer than 45 minutes No cardio Drink water all the time