[cross posted from body.livecurt.net for your convenience]
A calorie is 4.1184 Joules, which is roughly 4 watts. A calorie is a physical unit of potential energy. When burned by the body a calorie produces electrical and thermal energy as needed throughout the day. Calories come from 3 things: protein, fat and carbohydrates. Oddly, the worse of the three are the carbs. One gram of protein is 4 calories, one gram of carbs is 4 calories, and a single gram of fat is 9 calories.
Protein is the best thing you can get from your daily calorie allotment, it powers your muscles and acts as a stored energy source throughout the day that can be easily accessed. It is best to eat protein rich foods before and after working out for the biggest benefit to your body.
Carbohydrates are evil. They break down very fast and should almost always be utilized immediately, or else, you risk them slowing you down as the metabolism revs up to burn through them and then crashes you right back down after its done. Carbs are best to eat at breakfast, when you can use them as quick fuel to get you started and the chances of them being burned away almost instantly are very high. If you live a life that isn’t active at all, eliminating carbs is likely your only hope for weight-loss, but keep your protein high to protect your muscles.
Fats are GOOD! Fat is very hard for the body to store as fat, because it is more complex and takes too long to break down (your stomach cant just pass fat out to begin building a fat monument on your abs). Fats are relatively quick energy, and aren’t reserved for high-level muscle use. Fast-twitch muscles need a lot of protein, but the slower fibers will settle for the fats. Saturated fats are bad, avoid them if possible. Fats in nuts and milks are usually the best for your body because they usually are carrying other things that are really great for the body.
There is some good news, you can blow off 10% of the calories eaten each day to the digestive process itself.
Want to know how many calories you should eat per day? To determine the number of calories you need to maintain your weight, take your current body weight and multiply it by 11, then take that number and multiple it by your energy multiplier, then add whatever you burn during a workout. So.. in an easier form: (Current Weight*11*Energy Multiplier)+workout calories. If you want to gain weight (bulk), add 500 calories per day, if you want to loose weight, subtract 1000 calories per day.
*Energy multiplier: 1.3 (sedentary), 1.6 (light work), 1.7 (moderate work), or 2.1 (hard labor).
Just a little wisdom I picked up in my research.