The whole truth about calories

Let’s face it: calories are a measure of the guilt we all feel a little bit while eating. Or eating more than you should, because eating, feeding and nourishing yourself is fundamental to living, not just to be able to have a healthy and balanced sports life.

Yet we look at that number more or less obsessively: how many calories is a pizza? How many should I eat? How many in an apple? To arrive at the final question, which few ask:

What is exactly a calorie?

I’m getting there, although you can easily find the explanation on the net. If you don’t know it though, I can anticipate your reaction, “Okay, so what? I understood as much as before, that is, very little.”
To explain what calorie is and why it has become so important, we need to take a step back.

Wilbur Atwater

Who was him? He was a chemist who in the 1800s set out to measure the heat capacity of food. His purpose was to find a way to measure energy, particularly thermal energy. How to do it? Atwater built a machine consisting of a tub of water into which he dipped a container in which he had burned food. Degrees of positive change in water temperature measured the caloric value of the food in the “test tube.” The calorie (or Kcal, to be exact) is in fact defined as the amount of energy required to increase the temperature of one liter of water by one centigrade degree.

At this point you may wonder what water and temperature have to do with food and metabolism. Don’t blame yourself.

The answer is that it was an effective way to measure a quantity that could give information. Certain information, such as how food is processed in our bodies during digestion, since we are-we will see later when rightly so-thermal machines. That feed themselves and turn what they eat into heat. After all, “measuring” is a way of giving meaning and order to reality, so the idea that one could associate an “energy” number with foods was fascinating and comforting.

In short, our dear Wilbur began measuring different foods, and as incredible as it may seem, many of his measurements are still used today as valid references of the caloric value of foods. The food industry itself uses his studies as a reference for writing those numbers we all read on the packaging. After all, calculating nutrient calories since then is simple: lots of fat (9 calories per gram), lots of protein (4 calories per gram) and lots of carbohydrates (still 4 calories per gram).

Does counting calories make sense?

From a scientific point of view, calories indicate the energy power of foods, there is no question. What is overlooked is the fact that not all calories are equal and that different nutrients are absorbed in different ways by the body. Think of fiber for example: until not long ago it was thought that it had no calories because our bodies do not digest it and excrete it intact. Instead, it was recently discovered that some bacteria we have in our intestines feed on these very fibers, producing fats.

Then there is the difference between processed and unprocessed food to consider. For example, cooking makes foods more digestible and more easily assimilated. There is a difference between eating a pound of raw spinach and a pound of cooked spinach. The body struggles more to assimilate the former, expending more energy in the process and thus assimilating less. Yet at the start that pound of spinach has the same caloric value.

In other words: the more the food is processed, the more calories indicated are the ones your body will absorb (because it will have less difficulty metabolizing them).


Feeling satiated is basically the condition we all seek. When we are full, we don’t feel like eating anything else. We are not focused on the need to feed ourselves, so we do not worry about whether or not we will gain weight. Being full is also a psychological condition of balance, which is why we should prefer foods that make us feel that way. Instead of focusing on reading the calories on food packages (and the fact that we talk about “packages” already makes it clear that we are talking about processed foods) we should look out for the nutrients, knowing that:

  • fats and proteins require more energy expenditure and time to be absorbed, and as they are digested, they activate the release of a hormone that tells the brain the body has enough food (and thus tells it to stop eating)
  • carbohydrates require less expenditure and increase blood insulin levels, which instead … stimulates appetite.

So what?

At this point you always expect the advice, right? There is not one in particular, especially talking about nutrition, which is such a vast field that is not yet totally known. Instead, the point of this article is another: it is to push you to be aware of what you eat. In particular:

  • Foods have caloric value, but it then matters what form you take them in (cooked, raw, processed or unprocessed)
  • Calories are nothing more than a number. There is a difference between 100 calories of fat and 100 calories of carbohydrates, especially in how they are absorbed by your body
  • To have a balanced diet, you have to take in all kinds of nutrients, knowing that some give more satiety and others less, but that we need carbohydrates, fats and proteins (and minerals and vitamins and fiber). You can’t eat only steak because it’s the only way to solve the problem of satiety, sorry ;)

(From“The Calorie Myth” by Matthew MacDonald – Photo by Dose Juice on Unsplash)



related posts


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.