of bacteria in our gut. Some people have larger populations of
a Bacteroidetes (a species of bacteria), which are better at extracting
calories from tough plant cell walls than other bacteria species.
Margins of error
Nutrition Information labels can have a margin of error of up to 25%
on the packet of every foodstuff in your local supermarket can be off
by as much as 20-25%, making it hard to accurately gauge what your
‘energy in’ actually is.
Even if those food labels were correct, there’s another reason that
‘energy in’ is no picnic to calculate.
Reason 2: We don’t absorb all the energy we consume
The amount of energy a food contains in the form of calories is not
necessarily the amount of energy we absorb, store, and/or use.
Remember that the food we eat has to be digested and
processed by our unique bodies. The innumerable steps involved in
digestion, processing, absorption, storage, and use — as well as our
own individual physiological makeup — can all change the energy
balance game.
How processed?
We absorb less energy from minimally processed carbohydrates and
fats because they’re harder to digest, and we absorb more energy
from highly processed carbohydrates and fats, because they’re
easier to digest. The more processed a food is, the more digestion
work is already done for you.
Research has shown, for example, that we absorb more fat
from peanut butter than from the same volume of whole peanuts.
The researchers found that almost 38% of the fat in peanuts was
excreted in the stool, rather than absorbed by the body, whereas
seemingly all of the fat in the peanut butter was absorbed.
How prepped?
By eating a diet rich in whole, minimally processed foods, the number
of calories you absorb can be significantly less than you may expect.
Plus, they require more calories to digest.
Conversely, you will absorb more calories by eating lots of highly
processed foods, and burn fewer calories in the digestive process. In
addition, highly processed foods are less filling, more energy dense,
and more likely to cause overeating.
Since the number of calories someone thinks they’re consuming
could be off by 25% or more, their carefully curated daily intake of
1,600 calories could really be 1,200… or 2,000.
Taking all of these factors into consideration, it becomes clear
that this part of the equation should more accurately be: Energy In =
Actual calories eaten - Calories not absorbed
Clearly, there’s a big margin of error with regards energy input,
even if you’re a conscientious calorie counter. This doesn’t invalidate
the Energy Balance Equation. It just means that if you want an
accurate calculation, you probably have to live in a fancy metabolic
lab. For most people, it’s not worth the effort.
Energy out
‘Energy out’ varies a lot from person to person: it’s a dynamic,
always-changing variable.
There are four key parts to this complex system:
1. Resting metabolic rate (RMR)
RMR is the number of calories you burn each day at rest, just to breathe,
think, and live. This represents roughly 60% of your ‘energy out’ and
depends on weight, body composition, sex, age, genetic predisposition,
and possibly (again) the bacterial population of your gut.
A bigger body, in general, has a higher RMR, but, crucially, RMR
varies up to 15% between individuals. So, a 90kg guy with an RMR
of 1905 calories might find himself running alongside an identically-
sized guy on the next treadmill who burns 286 more, or fewer, calories
each day with no more, or less, effort.
2. Thermic effect of eating (TEE)
The way in which a food is prepared and whether it is cooked can affect its
bioavailability
We often absorb more energy from foods that are cooked (and/or
chopped, soaked, blended) because those processes break down
plant and animal cells, increasing their bioavailability.
When eating raw starchy foods (like sweet potatoes), we absorb
very few of the calories. After cooking, however, the starches are
much more available to us, tripling the number of calories absorbed.
Interestingly, allowing starchy foods to then cool before eating them
decreases the amount of calories we can extract from them again –
mostly due to the formation of resistant starches.
Gut bacteria
We may absorb more or less energy depending on the types
20 | NETWORK AUTUMN 2019
The less processed a food is, the greater the amount
of energy you will burn digesting it
Digestion is an active metabolic process. Thermic effect of
eating (TEE) is the number of calories you burn by eating, digesting
and processing your food. This represents roughly 5-10% of your
‘energy out’.
In general, you’ll burn more calories in your effort to digest and
absorb protein (20-30% of its calories) and carbs (5-6%) than you
do fats (3%).
And, as noted before, you’ll burn more calories digesting minimally
processed whole foods than you will highly processed foods.