Do you guys believe in calories?

[copemaxingll]

I agree, you’re right about the thermic effect of food and digestive efficiency

Although you're misunderstanding how nutrition labels work.

The calories on a label aren't raw calorimeter data, they are calculated using the Atwater system which explicitly subtracts the energy lost in human digestion and waste.

While individual absorption rates and TEF vary slightly from person to person, the numbers on the back of the package are already engineered to represent metabolizable biological energy.

It's a highly functional baseline

Atwater system is still a model based on averages, not a measurement of the energy a specific person will obtain from food.

Just because the system attempts to account for digestion and waste it does not mean it accounts for all the variables involved in human metabolism. Different foods with the same listed calories can have different levels of digestibility, different thermic effects, different fiber contents, and different food structures that affect how much energy is actually absorbed.

whole foods provide less metabolizable energy than highly processed foods yet having similar calorie numbers on paper. Two people can get different amounts of energy from the same meal because differences in digestion, metabolism, and gut microbiota.

So I agree that calories are a functional baseline and a tool for approximation. But my argument is that they are still an approximation. The fact that the Atwater system improves on calorimeter measurements it does not make calorie values an exact representation of biological energy availability.