Calorie Expenditure Charts
For Physical ActivityCalorie Expenditure Charts
For Physical ActivityKatch/Katch/McArdle
Calories
In Foods
Foods generally consist of a mixture of the three macronutrients-carbohydrates, lipids, and proteins. The burning of 1 gram of pure carbohydrate in the bomb calorimeter produces on average 4.2 kcal, 1 gram of pure protein releases 5.65 kcal, and 1 gram of pure lipid yields 9.5 kcal. Because the foods we consume have different proportions of these three nutrients, the caloric value for a given food such as apple pie and vanilla ice cream is determined by the amount of carbohydrate, lipid, and protein in an average serving. Thus, a food containing a large amount of lipid has a greater total energy (calories) content than a food that is relatively fat free. For example, there are 160 kcal in 1 cup of whole milk, whereas 1 cup of skimmed milk has only 90 kcal.
When 1 gram of carbohydrate or lipid is "burned" or metabolized in the body, it gives the same value of 4.2 kcal for carbohydrate and 9.5 kcal for lipid as it did in the bomb calorimeter. For protein, on the other hand, the energy yield is 4.4 kcal due to the loss of this nutrient's nitrogen component from the body. To keep the calculations simple, and to account for variations in each macronutrient's "digestibility coefficient," the values become 4 kcal for carbohydrate and protein and 9 kcal for lipid. Thus, one gram of lipid has more than twice the energy (kcal) content of a gram of carbohydrate and protein.
1 gram carbohydrate = 4 kcal1 gram protein = 4 kcal1 gram lipid = 9 kcal |
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