A calorie is a unit equivalent to the large calorie expressing heat-producing or energy-producing value in food when oxidized in the body.

It is an amount of food having an energy producing value of one large calorie.

1 gram of protein or carbohydrate has 4 calories and 1 gram of fat is about 9 calories.

An athletic person should eat at least 2.2 gram of protein per kg. of lean mass, but no more than 4.4 grams. They should eat at least 4.4 grams of carbohydrate per kg. of lean mass, but should not exceed 8.8 grams. At the most, a person should eat no more than 1.1gram of fat per kg. of lean mass, preferably less. All calculations are done from lean body mass, not total body weight, which includes fat.

The needs of your body depend upon your goals and your current activity level. For example, a 60kg. person and one weighing in at 120kgs. who are both trying to reduce body fat will each consume different amounts of calories, as well as individual nutrients. To lose 1 kg a week would require a daily calorie deficit of 1100 calories. You could eat less and burn off the rest through exercise. It really is that simple. In our opinion anything more complicated than that should be avoided.