How much does a calorie weigh?

Calorie counting is often cited as the solution for losing weight. Gained weight? Too many calories. Want to lose weight? Eat less. Sounds logical, but it doesn’t actually help…

Let’s start with the basics.

First, the numbers

• 1g carbohydrates ≙ 4 kcal
• 1g protein ≙ 4 kcal
• 1g fat ≙ 9 kcal

And, relevant for weight reduction:

• 1g fat tissue ≙ 7 kcal

Now we know what certain macronutrients contain, but we still don’t know what a calorie weighs…

What is a calorie?

“Calories” are a unit of energy. 1 cal is the energy needed to heat 1 gram of water by 1°C. Accordingly, 1 kcal is what’s needed to heat one litre of water by 1°C. Colloquially, people say “calories” when they actually mean “kilocalories” (kcal).

Food contains substances from which the body can extract energy. But it doesn’t contain calories in the sense that you could remove them, weigh them, or leave them out.

A calorie therefore weighs exactly… nothing at all. It’s a mathematical quantity that has no relation to weight.

The actual twist

What actually has weight is our food.

Suppose I decide to eat exactly 2000 kcal. If I do this using pure macronutrients (a thoroughly joyless meal), I’d need to consume 500g of food to get 2000 kcal from only carbohydrates or protein. For 2000 kcal from fat, only 222g - less than half.

So if I choose fat, I’ve only “put on” 222g. With carbohydrates it would be 500g.

This isn’t a dietary recommendation, just mathematics: energy and mass are simply not the same thing ⁽¹⁾.

I’m saying this with a wink - but we see that the classic limitation of looking at calories sometimes isn’t enough. It’s always worth to consider a different perspective to look at the situation. 😉

The body as a furnace?

Another aspect that further complicates calorie counting: parts of our food serve as building materials for muscles, hormones, cell membranes. But these are included in our calculated energy intake.

Pop quiz: who checks the fuel value of the IKEA shelf when they’re out shopping?

Calorie counting assumes the body works like a furnace: energy in, heat out, weight gone. Reality is considerably more complicated. It’s actually a hormonally regulated, complex biological system ⁽²⁾. In that context, it makes little sense to count a quantity that has no weight at all.

More about calories

Food Noise

The popular weight-loss injection promises less ‘food noise’ - and lists side effects. A ketogenic diet does the same, and comes with side benefits.

Hunger (in the Plural)

We act as if there were only one kind of hunger - there are actually three, and the dietary guidelines mostly talk about number four.

Insulin, Chapter 1

A closer look at some of insulin’s key roles: regulating blood sugar, driving fat storage, and ultimately influencing body weight

Grains

Grains are among the most fundamental staples - most people can hardly imagine doing without them. Yet depending on whether they are eaten by humans or fed to animals, they are credited with diametrically opposite properties. Schrödinger’s food

Overfed and Undersupplied

An alternative interpretation of hunger: what if we’re not hungry because we need to eat, but hungry because of what we ate? A useful mental model…

"Watch Your Weight"

A rant: why ‘watch your weight’ as advice doesn’t actually help

Caloric Balance: Cause or Effect?

An invitation to reverse the causality: why explaining weight loss through reduced calorie intake is not very helpful

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