Age has a lot to do with it. At age 15 I could eat everything, literally EVERYTHING I saw and never gain a pound. And I wasn't a bird eater either, I packed down the food and then some. I lived with my grandparents in high school who are from Oklahoma so I would have pancakes, eggs, fried potatoes, gravy and biscuits, etc.. for breakfast. For dinner I'd have things like pork chops, mashed potatoes and gravy, bread & butter with apple butter, etc... My grandma put oil in everthing and didn't know what low-fat meant. Then of couse like most teenagers I supplemented my diet with pizza, french fries, 6 packs of soda, cheeseburgers, cookies, etc... on a daily basis. I never played sports yet I managed to maintain a very lean physique my entire childhood up until my twenties. I graduated high school at 6', 185lbs and was less than 10% bodyfat and I never lifted weights.
When I hit my early 20's however the fat got revenge from all those years of neglect and eventually found a way to wedge itself firmly under my skin.
So it's hard to gauge your metabolism against teenagers(unless you are one as well), unless they are some of the unlucky ones that have a slow metabolism from the start. If you want to pack on muscle with as little fat as possible then I suggest going to Animal's board, check the forums and look for a post titled "cycles for pennies". It's a huge thread but inside lies all you need to know to get what you want. Doggcrap has laid out the basics from his years of experience and after reading all of the success stories I tried it out. I have to say I was able to eat more calories than I ever thought I could and managed to not gain a pound of fat. In fact I lost weight on what I thought was maintenance calories.
Combine DC's methods with the right supplements(searth the same forums for "anarchy stack" and I think you will be amazed.
Please Scroll Down to See Forums Below 
