It’s funny, the calories your body takes in may not be the same as the calories your body uses. Shocker? A 2500 calorie per day diet may cause some people to gain weight, or a 2500 calorie per day diet made up of of different foods could cause no weight gain or even a weight loss. It all depends on how the calories are counted and on how your body digests/uses those calories.
How Calorie Count Is Measured
Calories is the fancy term for the energy we use every day to measure the food we eat. One calorie is the amount of energy necessary to raise the temperature of one gram of water by one degree Celsius at normal atmospheric pressure. I know, I know, I will try not to get to sciency for you.
Calories in Food
When we talk about calories in food, we are actually talking about kilocalories. One kilocalorie is equal to a thousand calories. When talking about food, one calorie is actually a kilocalorie.
Manufacturers of different types of food are measured using what is called a “bomb calorimeter.” Stay with me….
The way the bomb calorimeter works: food is placed in a sealed container and water at normal atmospheric pressure. Electrical energy is used to burn the food. When the food is burned completely, the temperature of the water is measured and a calculation is made as to how many calories are in that food. That’s how we get calories on labels. But…
How The Body Uses Calories
The problem with the “bomb calorimeter” is that it measures every single available calorie the food contains. In our diets, we don’t always use up every available calorie. Most of us do not use every available calorie we eat.
For example, fiber. Fiber can be burned in a bomb calorimeter and its calories are measured as part of the total amount of calories in a specific food. But, in the gut, fiber is not digested (especially insoluble fiber) and it passes through the body to make up the bulky portion of poop. This means that the calories you ate from fiber aren’t absorbed and you are consuming fewer calories than you’d expect. This is why you may have heard to eat food with a lot of fiber because it makes you feel full.
And because you probably haven’t been in a science class in a long time…let me present….
The Atwater System
This is another method of determining calories. In this system, the calories are broken down into the number of calories in the protein, fat, carbohydrates, and alcohol in each food. For protein, there are 4 kilocalories in each gram of protein. There are also 4 kilocalories in each gram of carbohydrate. Fats contain 9 kilocalories per gram. If you drink alcohol, it takes up 7 kilocalories per gram of alcohol. (I know, it’s fair). The food is broken down into the amount of each of these components and the calorie count is added up.
Neither Method Is Truly Exact
Neither method is a perfect measure of the digestibility of food and the degree of absorption of the digested products. The truth is, the food that those calories come from greatly determines how they are processed in the body.
Calories are NOT created equal as the exact same amount of calories from two different types of food can pose completely different biological effects in the body.
In the next post I will describe a case study showing just that!
I’m curious, did you know, or did you believe that not all calories are created equal??