For some time when I was tracking my food, I was counting calories assuming it was some kind of an exact science. Calories in, calories, do the math…. Right? Well actually it’s a little more complicated than and in this article I’ll explain you why calorie counting is fundamentally wrong.

Make no mistake, the principles of energy balance works, meaning that when you take in more calories than you expend, you gain weight and when you take in fewer calories than you expend, the opposite happens and you lose weight.

However, counting calories as a way to try to know, and control, your intake is often and sometimes hopelessly flawed.

Firstly, you can’t really trust that the macronutrient (proteins, fats and carbs) numbers you see on food packaging. Because the way they’re calculated (that is if they’re calculated at all) can be is surprisingly imprecise.

Plus, even if food package numbers were precise, once the food is cooked, steamed, chopped, or blended, the amount of energy available for digestion and absorption changes.

Then there’s what happens once that food enters your body… how do you chew it, digest it, absorb the nutrients etc… so your calorie intake can be influenced by a multitude  of unexpected factors.

And in this article I wanna share with you some of the biggest problems with calorie counting as it relates to the “calories in” side of the energy balance equation.

Food labels.
The calorie counts on food labels and in databases (yes also the ones in the food tracking apps you are using) are just averages. Research shows that the true calorie content is often significantly higher or lower.

Food companies may use any of 5 different methods to estimate calories and controlling organisms sometimes allow for inaccuracies for up to 20%. Which in essence means that 100 calories on a food label may vary somewhere between 80 and 120 calories.

We don’t absorb all the calories we absorb.

Some calories pass through us undigested, and this varies from food to food.

For decades, scientists have used the following formula to come up with calorie counts that reflect only what we absorb.

Macronutrient per gram

Total calories per gram

Calories available for absorption

Calories not absorbed


5.65 Cal

4 Cal

1.65 Cal


9.45 Cal

9 Cal

0.45 Cal


4.10 Cal

4 Cal

0.1 Cal

But this formula does not tell the entire story because the formula doesn’t work for nuts and seeds because we absorb fewer calories from them than calculated.

The formula is wrong about fiber-rich foods, of which we absorb more than what the formula calculates and it turns out that the number of calories available for absorption from protein-rich foods is more variable that the formula calculates.

On average there is a 10% error.

The way you prepare food changes its calorie load.

Cooking your food generally makes more calories available for absorption and food labels don’t always reflect that. Also, chopping or blending your food increases the calories absorbed.

Errors can be as high as 90% (OMG)

 Individuals absorb calories uniquely (and variably).Our own individual gut bacteria can increase or decrease the calories we absorb. People with a higher proportion of ‘Firmicutes’ bacteria absorb on average 150 calories per day more than those with a higher proportion of ‘Bacteroidetes’.

You aren’t that great at measuring.Studies show that people mis-measure portions about two thirds of the time, so it’s easy to accidentally consume a lot more calories than you intend to.

So, because

  • Food labels are usually not accurate;
  • We don’t absorb all the calories we consume;
  • The way we prepare our food changes its calorie load;
  • Individuals absorb calories uniquely; and
  • People aren’t great at measuring.

Calorie counting may not be worth the effort

Author: Peter Koopmans