First, what is a calorie?
Calories are essentially units of energy that you get from the carbohydrates, protein and fat content from foods you eat and are used by the body to perform basic functions of living such as breathing, digesting, walking, talking, etc.
Simply put, calories become a problem when you absorb more calories that you need because they will be stored as fat for later use. This may have been great during the caveman years when food was scarce, however that is not the case today.
A very common misconception is that all calories are equal, and that 100 calories of say potato chips are absorbed the same way as 100 calories of say chicken. Here are some reasons why calorie counting doesn’t always add up and some incentives to eat more natural foods.
1. Your body does not absorb all calories from some foods.
For example, almonds. Recent studies have found that about 20% of the calories from almonds are not absorbed by the body. This means if a package advertises a serving of almonds to be 160-170 calories, you are actually only absorbing about 120-130 calories.
2. Your body absorbs more calories from cooked food compared to raw foods.
Cooking breaks down the bonds in food that hold it together, which makes it easier for your digestive system to break down food. In effect, your body doesn’t have ato work as hard to break down the food and less energy and calories are lost to digestion. When food are raw, all the bonds are intact making your digestive system work harder to break down food. Think about when you bite into a raw carrot compared to a cooked one, which one is easier?
3. Your body burns more calories with protein.
Up to 30% of calories from protein are lost to digestion, meaning if you eat 100 calories of protein, you are only really absorbing 70 of them (this also is dependent on the type of protein you are using whether it be natural or supplement). This is because proteins are built up of several amino acids, which have very strong bonds holding them together. It takes a lot of effort by your digestive system to break these bonds down, in effect causing you to take in less calories.
4. Your body absorbs less calories with fiber.
There are a couple of main reasons you will take in less calories with fiber rich foods. First of all, the human body cannot absorb the calories from fiber. This means the calories listed in your food that are attributable to fiber are not actually used (fiber is listed in the carbohydrates in nutrition label with 4 calories per gram). Secondly, our digestive systems work extra hard attempting to break down fiber leading to more calories being lost in the digestion process. This means your net calorie intake from fiber rich food is a fraction of what the nutrition label might say.
5. Gut bacteria can influence how many calories are absorbed
Gut bacteria help with the breakdown of food and effect the amount of calories you absorb from food. Research shows that there are two main types of gut bacteria that regulate calorie absorption, the firmicutes and the bacteroidetes. Obese individuals tend to have more firmicutes in their gut while lean individuals tend to have more bacteroidetes. Researchers attribute this to firmicutes being able to extract more calories from food and store it, leading to weight gain.
A sedentary lifestyle and a diet high in fat and sugar has been found to increase the firmicutes in the gut, while physical activity and a diet high in plants and low in sugar and fat is associated with more bacteroidetes in the gut. This is a relatively new research area, and more research is currently being done to better understand the role of bacteria in our gut.
So to answer the question by the title, no a calorie is not a calorie. They are not all equal. Some absorb better than others.