If you want to eat for maximum health and energy, you have to break down your food intake into carbohydrates, protein, and fats, then figure out how each contributes to your total calorie intake. It isn't as tough as it sounds. First, if you're going out for more than a couple of days, you'll need 3,500 (women) or 5,500 (men) calories a day-in the 65-15-20 ratio-to maintain weight and energy levels. Sports nutritionists recommend that athletes involved with moderate, long-duration activities like backpacking eat 4 to 6 grams of carbohydrates per pound of body weight per day. So a 125-pound female backpacker who wants to maintain the recommended 3,500 calories a day would need to consume about 500 grams (4 g. x 125 lbs.) of carbohydrates, as shown in "Energy For A Day."