What Calories Do?

[Gourav]

Humans need energy to survive - to breathe, move, pump blood -and they acquire this energy from food.

The number of calories in food is a measure of how muchpotential energy that has food. One gram of carbohydrate has 4calories, one gram of protein has 4 calories and one gram of fathas 9 calories. Food is a compilation of three building blocks. So if you know how much carbohydrate, fat and protein in the food provided, you know how many calories, or how much energy, thatfood contains.

If we look at the nutrition label on the back of packets ofmaple-and-brown-sugar oatmeal, we find that it has 160 calories.This means that if we pour this oatmeal into a dish, set theoatmeal on fire and get it to burn completely (which is actually quite complicated), the reaction would produce 160 kilocalories(remember: food calories kilocalories) - enough energy to raise temperature of 160 kilograms of water 1 degree Celsius.

[Gourav]

If we look closer at the nutritional label, we see that our oatmeal has 2 grams of fat, 4 grams protein and 32 grams ofcarbohydrates, resulting in a total of 162 calories (apparently,food manufacturers like to round down). Of these 162 calories, 18come from fat (9 cal x 2 g), 16 derived from protein (4 cal x 4 g)and 128 come from carbohydrates (4 cal x 32 g).

Our bodies "burn" calories in the oatmeal through metabolic processes, the enzyme that breaks down carbohydrates intoglucose and other sugars, fats into glycerol and fatty acids and proteins into amino acids.

These molecules are then transported through the blood strea min to cells, where they are either absorbed for immediate use or sent to the final stage of metabolism in which they react with oxygen to release their stored energy.