Q: How many grams of carboyhydrates does an average teenager need daily?

A: Sorry, that's kinda tough to answer in general. Typical consumption for an average growing boy might be around 400-500 grams of carbs. I would recommend a lower-carb, higher-protein diet. For your specific case, just fill outhttp://www.mikesfitness.com/content/fitnessguide specifying 'Build Muscle' as your goal -- a typical teenager should not in general try to lose fat, so build muscle is a more appropriate goal for the Guide.