What is a calorie? Without them we couldn’t survive. A calorie is a unit of energy. Calories give us energy. We tend to associate calories with food only, but they apply to anything containing energy. How about gasoline, yep, gas has energy and a lot of it. A gallon of gas contains about 31,000,000 calories. Wow! That will put the pounds on!
Specifically, a calorie is the amount of energy (or heat ) it takes to raise the temperature of one kilogram of water 1 degree Celsius. For all you geeks out there a calorie is equal to 4.184 joules, a common unit of energy used in the physical sciences.
Humans need calories to survive, to breathe, move, and we acquire this energy from food. The number of calories in a food is a measure of how much potential energy that food possesses. A gram of carbohydrates has 4 calories, a gram of protein has 4 calories, a gram of fat has 9 calories. Food is a compilation of these three building blocks (macro-nutrients). If we look at the back nutritional label of any given food and it reads that it contains 160 calories that means that if we could ignite that food and get it to burn completely it would produce enough energy to raise 160 kilograms of water 1 degree Celsius.
Our bodies “burn” the calories in food through metabolic processes by which enzymes break down the macro-nutrients into glucose and other sugars. These sugar molecules are what our bodies use for fuel. These molecules are then transported, via the blood stream, to the cells where they are either absorbed for immediate use or stored.
The BIG question is just how many calories do we need to function? Well everyone is different. It depends on three things: Basal metabolic rate, Physical activity, Thermal effect of food.
I’ll get into these three criteria in my next e-mail. But before I go remember that when a nutritional label lists the amount of calories on back, it is for one serving. You NEED to check how much a serving is. And how much you are actually eating. Is it a serving or four servings? Usually the servings are minimal, and we are eating much more.