There are many variables that go into any type of diet.
All
too often people try to describe complex things in the world in terms of black
and white. This is particularly true with dieting, specifically the
two sides of the “caloric balance”. One side says “eat less, move more”
and one side says “eat this not that”. The “if it fits your macros”
camp will tell you that as long as you eat fewer calories and exercise a lot,
you will lose weight. The “good calories bad calories” will tell you
to avoid processed foods and eat lots of veggies and healthy meats and you will
lose weight? Who’s right and who’s wrong? Both!
It
really doesn’t take too much reason to find flaws in both camps- they do it to
each other all the time. If you give a severely obese child nothing
to eat but Snickers, Doritos and Coca-Cola (making sure it’s around a 20%
deficit of total daily energy expenditure, let’s say around 500 calories less
intake than expended) will the kid lose weight? Likewise if you
gorge yourself on fresh fruits, veggies and meat at a 1000 calorie surplus on a
daily basis, will you lose weight? Let’s take a closer look at some
simplified equations to perhaps find an answer.
First
off, if someone tells you that weight loss is easy, it’s all about the first
law of thermodynamics you should at minimum walk away from them, probably
run. Before hand I would suggest laughing at them, or perhaps giving them
a good smack. There are so many people who have become experts in the
field of weight loss and will prescribe simple solutions such as “eat less and
exercise more, it works because of the first law of thermodynamics. ” I
find this slightly offensive, and as an engineer that is gets paid on a daily
basis for doing actual real work involving the first law of thermodynamic, I
tend to want to strangle people who mention this.
The
first law of thermodynamics states:
“THE
INTERNAL ENERGY OF AN ISOLATED SYSTEM IS CONSTANT”
Mathematically:
dU=
dq + dw
The
equation can be verbalized as the change in internal energy of a closed system
(U) is equal to the energy that passes through its boundary as heat (q) or work
(w). For the non-math geeks, the “d” in before U, q, and w is
basically denoting a small change or differential.
What
people are really trying to invoke is energy balance- and there is a
difference. The first law of thermodynamics is a descriptor for a CLOSED
thermodynamic system. That means there is no mass exchanged between the
outside of the system and the inside of the system. Obviously, people who
say weight loss is all about the first law of thermodynamics really don’t know
the first law, don’t know what they are talking and perhaps don’t understand
matter is typically both inputted and outputted from humans, despite the fact
that they may lack the output as they are most likely full of $#!T. While
the first law does imply energy conservation, it is in terms of the change in
the internal energy of a CLOSED system being equal to the heat added to the
system and the work done by the system. Honestly, it’s not built to be
applied to the human body- it’s a little bit of a stretch to do so.
What
they are really after is the energy balance equation usually stated in some
form of “you have to burn more than you consume”, or “If you take in more
energy than you burn, your body will store the excess as fat. And
likewise if you don’t take in as much as you need, your body will burn
fat”. Again, this is a simplification and almost seems to imply
causation.
Our
bodies are really chemical reactors, and we can create equations to account for
the conversation of energy and mass. This is standard operating
procedure for chemical engineers. The balance equation should really be stated
more along the lines as
Energy
Input to the body = Energy Output from the body +disappearance of energy by
chemical reaction within the body + Accumulation of energy within the body
There
is nothing in the energy equation that directly accounts for
mass. The mass balance must be performed similarly,
Mass
Into the body = Mass Out + Mass loss due to chemical reaction within the body+
Accumulation of Mass within the body
The
two equations relate to each other in terms of the chemical reactions that take
place in the body. To put everything in terms more closely related
to the human body we will structure the above equations to simplify things a
bit:
Calories
In = Calories Out + Net Change in Mass
Now
I’m all for simplification and assumptions, however the fastest way to the
wrong answer is oversimplification and the wrong assumptions. The
first problem is simplification of the “calories out” term. Calories
Out is made up of more than just exercise (exercise for most people is actually
a very small percentage of the total). The majority of calories out
for most people will be due to basal metabolic rate (BMR), the daily energy
requirements for the functioning of all our organs. Additionally
there is the thermic effect of food (TEF), basically the energy required to
process food ingested. Finally calories are used for external work,
basic physical activity. Some sources will refer to this as physical
activity level (PAL), some refer to the Thermic Effect of Activity
(TEA). Some researchers have further tried to complicate the
activity breakdown by including Non-Exercise Activity Thermogenesis (NEAT) or
Spontaneous Physical Activity (SPA). So substituting these new terms
into the balance equation we have
Calories
In= BMR + TEF + PAL +SPA + Net Change in Mass
Rearranging
this so we can see it in terms of mass change:
Net
Change in Mass = BMR + TEF + PAL +SPA - Calories In
The
“eat less exercise more” people will assume that food in and energy used on
exercise are the only adjustable variables in our equations. In
fact, most of these terms are interrelated, and changing one will most likely
affect another.
For
example, doing a lot of hard “metabolic conditioning” type training, something
like Crossfit, or P90X, will burn some calories (PAL goes up) will also deplete
muscle glycogen stores and lower the metabolic rate (BMR goes down!)1. To
complicate things even more, prolonged light exercise has been found to
increase metabolic rate2. So
studies have shown that increasing PAL can both increases and decrease
BMR. It has also be proposed that increase in physical activity
results in less weight loss than expected due to changes in other components of
the energy balance equation9.
Not
only does exercise affect metabolic rate, but the food you eat after your work
out will also affect your metabolic response- a carbohydrate reefed after
exercise will increase BMR1. In
fact, it has been regularly argued that the makeup of the Calories In
macronutrient profile (protein, carbohydrate and fat) can affect weight change
due to energy inefficiencies3, 4, 5.
This
leads into the TEF; any change in calories in will also change the TEF (less
food, less energy to process it, more food, more energy to process it).
Additionally, not all calories will be processed (chemically reacted) by the
body in the same way, and the efficiencies of these reactions will be
different. So by changing the composition of the calories in, the
TEF term equation will be altered. For example, it has been shown
that whole food has a much larger effect than processed food6. More
specifically, the thermic effect of protein is 20-35% of the calories, 5-15%
for carbohydrates, and 0-15% for fat8. This is
basically to say for every 100 calories of protein ingested, 20-35 calories
must be used by the body to process it. To further complicate things, TEF is
not only dependent on the type of food, but on the person eating the food- people
with insulin sensitivity and obesity have a blunted TEF7.
Increase
in caloric intake may also cause some people to fidget or move around more,
burning calories and becoming resistant to weight gain when overeating10. Thus,
increasing the Calories In, may, for some people, affect the amount of
spontaneous physical activity, and thus change how many calories may be burned.
In
conclusion I would like to summarize that the energy balance equation does hold
true, however, it is not as simple as most people make it. A calorie
really isn’t a calorie (not even mentioning some of the psychological
aspects). Changing the exercise and amount of calories ingested, and
specifically the type of exercise and calories ingested, will have effects on
other components of the energy balance equation. To from an article
by Dale Schoeller quote “Using the energy balance equation to predict weight
change when only energy intake is know or when only energy expenditure is know
is not valid because that calculation makes the assumption that the other term
will not change… because changes in any one term often are met with a response
that counters some of the effect of that change on energy balance.”11
When
you get down to brass tacks, both the calories you eat, the type of calories
you eat, the exercise you do, and the type of exercise you do, all in
combination with each other must be taken into account for weight loss and
optimum health. Not everyone can blindly eat less and exercise more,
or only eat healthy. Granted, if it works for you, then all is
well. But it may not be as easy for all people. Some
people can get away with eating anything they want and exercising away the fat,
however they are few and far between. There are people who eliminate
sugar and processed carbs from their diet and the fat melts off, but not
everyone has the will power. There are many variables that go into a
weight loss diet (or weight gain/bulking diet), and the key is finding what
works for you.
As
for our two examples in the second paragraph, I’ll let you decide.
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