A Calorie is and isn’t a Calorie

A Calorie isn’t a Calorie?


Recently I have seen a lot of talk about the idea that a calorie isn’t in fact, a calorie, which of course is misleading to anyone not interested in the science of it all. It sends a message that tells people that actually you can eat more without consequence. We all know, deep down this is wrong.

The traditional theory is that if you eat too many calories you will gain weight. Eat a few less than you burn and you will lose weight. Simple.

It seems that a lot of people are up in arms about the fact that a diet rich in protein has been seen to allow for greater weight loss when the same number of calories from carbohydrates are consumed. The calories in versus calories out theory thus comes under fire as being wrong. It’s not and doesn’t take a moment of understanding to see why…


Where this gets confusing is that not all calories demand the same amount of “attention” from the human body.

For example;

1000 calories from protein will not actually yield the same amount of usable energy as 1000 calories from carbohydrates. The reason is down to what is being called the thermic effect of food.

Protein requires more energy to break down and assimilate than carbohydrates do.

Out of those 1000 calories from protein your body may well use 250 calories of energy to digest it where as it may only need 100 calories of energy to digest the same 1000 calories of carbohydrates which obviously leaves less energy for you to use or store as fat from the protein rich diet.

harder to digest

harder to digest

Not so junk and not so tasty

easier to digest


The calories in versus out theory is still very much intact. All that happens is that by simply eating more protein you have increased your calories out side of the equation.


Nothing magical about that, we all knew that a little extra protein in your diet is a good thing.

Not all calories are equal but the calories in versus out theory is still solid;

Take two diets of equal calories, one with 2000 calories from protein and one with 2000 calories from carbohydrates and yes, over the long haul the thermic effect will show the protein rich diet as being more effective at weight loss by a small margin.


Thus to a casual observer it would appear that the calories in versus out model is wrong.

Explain to them the above and all is well.



Epsom & Surrey Personal Trainer, R Ham Williams


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