Nutrition 101: What is a calorie?
Simply explained, a calorie is a unit of measurement. A calorie represents the energy in food, or more precisely Macronutrients. Macronutrients are protein, carbohydrates, and fat. Two of these, protein and carbohydrates, have four calories per gram. Fat has 9 calories per gram.
This means when your body needs fuel it can burn the calories in food for energy. If you eat more calories than your body needs at any given moment, it doesn't burn those calories but stores them as body fat. When you create a calorie deficit, whether through activity or diet, your body taps into it's energy stores. First, your body burns any glycogen stores in your muscles, which are limited. Then it taps into fat stores, which are nearly unlimited.
In scientific terms, a calorie is the amount of energy it takes to raise the temperature of one gram of water by one degree Celsius. Calories in food represent how much energy is in that food. This means an apple that has eighty calories provides your body with enough energy equal to raising that gram of water by eighty degrees. Except your body uses the fuel in the apple to do any number of functions.
If you eat a double cheeseburger and fries with a thousand calories, your body could heat that gram of water to one thoousand degrees. But your body rarely needs a thousand calories all at once, unless your competing in an Ironman competition. Your body will convert the extra calories into body fat. Unless you give your body a reason to retrieve that stored fat, like exercising or dieting, it pretty much stays in storage.
Cheeseburger 20 years ago had 333 calories well a modern cheeseburger contains 590 calories.
