Ever wonder who the hell the FDA's 2,000-calorie-a-day recommendation was intended for? Probably not you. If you're even mildly active, chances are you've burned 2K by lunch. Thankfully, the Institute of Medicine at the National Academy of Sciences in Washington, D.C., issued its "Dietary Reference Intakes" report in September, offering a more realistic guide based on height, weight, and physical activity. According to the report, a brisk walk for an hour each day makes you an "active adult." Knowing that, guys should take a look below for a better approximation of how much to eat.