A calorie is not a calorie
Zoë Harcombe
We have two calorie articles in
this edition of Diet & Health
Today and we make no
apologies for this. It is the
single most important belief,
which people need to stop
holding true, if they want to
achieve long term weight loss.
Sam Feltham 'took one for the
team' doing his fascinating 'same number of
calories/different type of calories' experiment to
show that a calorie is not a calorie. Here's why...
Introduction
"A calorie is a calorie" is considered one of the
founding truths of dieting. It doesn't matter what
you eat - the only thing that counts is calories.
Consume less, expend more and thou shall lose
weight. It all sounds quite sensible; sadly, it is
anything but.
We know that calories are not equal nutritionally.
100 calories of table sugar has no essential fats,
no protein, no vitamins and no minerals. 100
calories of liver (I know - me neither) provides
virtually every nutrient that a human needs.
Cutting nutrient rich foods (meat, fish, eggs, dairy,
nuts, seeds) for nutritionally poor foods (cereals,
dry toast, pasta salad, fruit) is bad for our health,
but we have made these low-fat/high-carb choices
because we thought they were good for our
weight. I hope to show you how wrong this belief
is...
Two vital truths about calories
Truth 1 – a calorie is not a calorie
A calorie as a unit of energy is a calorie as a unit
of energy, just as an inch as a unit of length is an
inch as a unit of length. However, that’s as far as
this statement (a tautology to be precise) goes. A
calorie is not a calorie the minute it enters the
human body.
We are indebted to three scientists for our
knowledge in this area. Eric Jequier, who works at
the University of Lausanne, Switzerland,
calculated the thermic effect of macro nutrients.
Diet & Health Today
That means he worked out the number of calories
that are used up in making energy available to the
body for the three different macro nutrients:
carbohydrate, fat and protein. He found that
approximately 6-8% of carbohydrate calories
consumed are used up in converting that
carbohydrate into energy; the number is only
2-3% for fat, but that 25-30% of protein calories
are used up by the body in breaking down protein
into amino acids – the component parts of protein
needed by the body.1
This means that if we ate 100 calories of pure
carbohydrate (sugar), approximately 93 calories
would be available to the body as energy. If we
ate 100 calories of protein (egg white, as an
example), perhaps as few as 70 calories would be
available to the body for fuel.
Richard Feinman and Eugene Fine, a biochemist
and a nuclear physicist respectively, published a
paper in 2004 building on Jequier’s work.2 They
took Jequier’s mid points (7% for carbohydrate,
2.5% for fat and 27.5% for protein) and worked
out how many calories would be available to the
body if someone consumed 2,000 calories in the
proportions 55:30:15 carbohydrate:fat:protein.
These are the proportions that the UK and USA
governments advise us to eat. If anything, our
governments would be happy if carbohydrate
intake increased to 60% at the expense of fat and
the February 2013 Australian Dietary Guidelines
have suggested 65% would be a good target
( h t t p : / / w w w. z o e h a r c o m b e . c o m / 2 0 1 3 / 0 2 /
australian-dietary-guidelines-feb-2013/).
The answer is that 2,000 calories consumed in
the 55:30:15 proportions ends up as 1,826
calories available for energy. If the same 2,000
calories were consumed in a 15:30:55 high
protein diet, (keeping fat the same and swapping
carbs out and protein in), the calories available to
the body drops to 1,662.
Truth 2 – some calories have a job to do
You'll be familiar with the term Basal Metabolic
Rate (BMR). The BMR calories are the fuel
needed by the body just to do all the things that
the body does, even if we're ill in bed all day – cell
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