The Calorimeter Problem: Why the Theory That 'A Calorie is a Calorie' Doesn't Hold Up

The calorimeter is a device that measures how much potential energy exists in various foodstuffs. Proteins and fats contain 4 calories per gram, while fats contain 9 calories per gram. Since fats are more than twice as caloric per gram than carbs and proteins, dietary fat therefore appears to be uniquely fattening.

KEY POINT: The body "sees" the energy from different foods differently.

But is the really the case? Are all calories really 'equal'?

If not -- if it can be shown that the quality of calories "matters" -- then the idea that "a calorie is a calorie" must be thrown out. This would discredit the Caloric Balance Hypothesis and support our alternative hypothesis, Lipophilia.

Let's look at evidence.

1. Here's a very interesting article from the website of a trainer named Lyle McDonald.[1]

He shows that the energy balance equation that we've been discussing is far more complicated than most people realize. Factors such as non-exercise activity thermogenesis (NEAT) and resting metabolic rate (RMR) can influence our energy stores. Those factors would not impact a calorimeter. He also tells us that:

"not all foods are digested with identical efficiency."

2. Here's another article by McDonald - also very provocative. He asks:[2]

"Is a calorie a calorie? Simply put, the debate comes down to this: is all that matters caloric balance (calories in versus calories out) or do the source of the calories matter? The short and simple answer, of course is 'no.'"

3. Here is another article that discusses some of the same points that McDonald makes:[3]

"A calorie is not a calorie, in more than one sense. Carbohydrate, fat, and protein calories are indeed equal by definition in terms of their energy content, but the body processes each in a distinct way, and these differences have real implications for weight management. In addition, food calories of all types may have very different effects on the body depending on when they are eaten and what they are eaten with."

The article then provides five reasons why the calorimeter hypothesis -- that "a calorie is a calorie" -- flops.

4. Gary Taubes argues the same point here.

So what's the takeaway?

The takeway is that the human body is different from a simple calorimeter. We're not car engines. We're complicated. Our bodies "see" the energy from different foods differently. Different kinds of calories have different kinds of effects on the body.

Think about this from the perspective of your own experience. Imagine drinking 1,000 calories worth of melted lard. Would that be harder or easier than eating 1,000 calories worth of freshly baked brownies? Which would you rather do? How would you feel after drinking a cup of fat? Would you feel hungry? Probably not. You'd probably feel gross, like you never wanted to eat again. How would you feel after eating a few brownies? Would you feel hungry? Probably. Probably you'd want some more brownies.

Sugars, fats, and proteins have profoundly different effects on hunger and metabolism, and that's what this whole debate is about. Because everyone knows -- at least on some level -- that the idea that "a calorie is a calorie" does not mesh with our experience in the real world.

But if we accept the idea that not all calories are "equal," then the theoretical justification for the Caloric Balance Hypothesis falls apart.

References