Myths, Metabolism, and Appetite
Humans have been evolving for the better part of 2 million
years. During the vast majority of this
time, approximately 1.97 million years, we’ve run, we’ve jumped, we’ve swam,
we’ve paddled, we’ve climbed, we’ve crawled, we’ve thrived. The adaptability our genome has given us has
allowed us to survive in every environment we’ve encountered up until now. Recently, technology has allowed our environment
to evolve much more quickly than our genes allow us, leading to an epidemic of
obesity and Type 2 diabetes. This
epidemic costs the country nearly $300 billion per year.
It’s not terribly difficult to identify the aspects of our
environment that have led us to this epidemic. A clever primate that has flourished in environments
where food is scarce and physical activity is a requirement to find food is not
suited to an environment where physical activity is optional and food can be
attained quite easily. This primate has
been naturally selected over the course of millions of years to eat when food
is available and to exert as little energy as possible to get that food. Now that the environment allows this very
thing, we are getting the product of that gene/environment interaction and it’s
not pretty.
All is not lost, however.
There is quite a bit one can do to turn this predicament around, we just
need to be that clever primate and look deep within science for solutions. Unfortunately, our current course is both not
working and, when you look at what the science shows, actually driving us
deeper in to the hole that we’ve dug. In
part 1 of this series we will discuss how the conventional wisdom being passed
off to you by your doctors, trainers, and the popular press is all wrong. In part 2 of this series, we will discuss how
your metabolism works and how this runs counter to what they tell you. In part 3 we will discuss diet and the
science behind why we continually fail.
PART 1
When you go to your doctor and present as obese or
overweight, their standard of care is to tell you to eat less calories and burn
more. For most people this does not
work, and in a good chunk of the people that it does it only works in the
short-term, eventually leading back to the same weight or even worse, more
weight gain later down the line. Much of
this, as well as nearly all processes in the body, is driven by hormones. Hormones are chemicals that the body uses to
communicate between systems. We can use
what we know about hormones to control many things related to weight such as
appetite, energy levels, stress levels, and fuel selection. Telling someone to count calories and burn
more completely ignores these hormonal shortcuts, making the task of weight
reduction and maintenance much more difficult.
Of the advice that you are given, there are 4 key notions that mislead
people down the wrong path: A calorie is a calorie, burn as many calories as
you can, carbohydrate is the body’s preferred fuel source, and whole grains are
good for you,.
A Calorie is a Calorie
Before we go on, it is important to say that, of course, a
calorie is a calorie, what else would it be?
The problem with this notion is that it is irrelevant to the
discussion. For one, we can all agree
that ammunition is ammunition, but a BB pellet and a bazooka shell are not the
same thing. They may share a few common
traits, but for the most part we can all agree that they probably have more
differences than similarities. In much
the same way, the calories you consume are quite different from one another based
on their source.
Most people look at their food as energy and that energy is
measured in calories. What most people
don’t realize, however, is that we do not even use our food for energy, we use
a substrate called ATP (Adenine Triphosphate).
All of our cells use ATP for energy, and ATP is stored within our cells
and recharged with the food we eat. As
such, there is no calorie receptor on your cells, and your cells do not look at
what you consume as calories, it views it as raw materials. Once the food you eat is broken down in to
amino acids from protein, glucose from carbohydrate, and fatty acids from fat,
it can enter your cells. The kicker here
is that not all of what you eat is used for energy. All of it can
be used as energy, but your body uses amino acids to build structures and
enzymes to catalyze reactions and fats to build hormones and repair cell walls
on top of what they provide for energy.
Certainly these proteins and fats contained energy when you consumed
them, but if you are not using them for energy purposes, do we really concern
ourselves with the calories they contain?
But wait, it gets even more interesting.
A nutrient is considered essential when the body needs it but
cannot manufacture it from other nutrients.
Therefore, you need to eat this nutrient directly in order to remain
alive. There are essential amino acids,
essential fatty acids, but there are no essential carbohydrates. But how can this be? It’s actually quite simple, your body needs
glucose which carbohydrates provide, but so can amino acids and a portion of
the fat molecule called glycerol. The
conversion of non-carbohydrate to glucose is called gluconeogensis and is
performed by the liver under the direction of hormones. In fact, for 1.97 million years,
gluconeogenesis probably provided the bulk of our glucose needs with vegetables
and fruit kicking in as well. Obviously
since agriculture became big this has changed, and that is one of the primary
drivers of our current obesity epidemic.
With the way our bodies work, this could eventually lead to the human
genome shedding the genes necessary for gluconeogensis, which would be a bad
scene if carbohydrates ever become scarce again.
As mentioned above, carbohydrates are broken down in to
glucose and fats are broken down in to fatty acids so they can enter our cells
for regeneration of ATP. Amino acids
provide energy as well, but only after being converted in to glucose
first. But what are the differences
between glucose and fatty acids with regard to their energy qualities? The first and most striking difference is
that glucose recharges ATP at a much faster rate than fatty acids do.
If you are looking to sprint short distances or perform
explosive movements such as jumping, fatty acids cannot recharge ATP stores
fast enough so you fatigue once your ATP stores are used up. To perform this type of activity for a
considerable amount of time, the bulk of ATP regeneration will come from the
breakdown of glucose with fatty acids providing a small amount. Once you stop performing the explosive action
or decide to do something more along the lines of long distance running or
walking, fatty acids will kick in the bulk of ATP regeneration.
While fatty acids are much slower at recharging ATP, they
recharge a lot more of it. The breakdown
of 1 glucose molecule will yield 38 ATP while the breakdown of a fatty acid
molecule will yield 128 ATP, which is quite a difference. So, while a calorie may be a calorie, are
glucose and fatty acids the same? The
reactions by which they recharge ATP are completely different, with glucose
being metabolized anaerobically (Without oxygen) within the cytoplasm of the
cell and fatty acids being oxidized aerobically (With oxygen) by the
mitochondria. Given the qualities of
each, they seem suited for different goals.
Specifically, glucose is a more
appropriate fuel source when you need bursts of energy while fatty acids are a
more appropriate fuel source when you need a lot of energy but are in no hurry
to get it.
Making the “A calorie is a calorie” approach even more
frustrating and weak is the fact that as you cut calories your body adapts by
burning less calories to accomplish the same tasks. This is true and happens even with no loss of
muscle mass(1, 2, 3). So while it is still true that a calorie is a calorie,
your body changes the rules of the game by burning fewer calories to do the
same thing. Now you need to either cut
more calories out of your diet or burn more.
By the time you get anywhere near your goal weight you’ll be eating 500
calories a day and exercising 10 hours a week.
The current theory on why this happens is that your body
resists burning fat because it is holding on to energy in case of famine. This is a nice theory and all, but if you
look deeper it is certainly not the case.
Why? Because when you increase
your caloric consumption your body adjusts by burning MORE calories, and it can
do this to the same extent as lowering metabolism when you lower calorie
intake. If the human machine is so
concerned with conserving calories, why do the rules change during
overconsumption of calories?
Obviously this is an adaptation to the environment and not
some uni-directional stress mode that rains on your weight loss parade. Lowering your metabolism is basically your
body’s way of becoming more efficient, burning a smaller amount of energy to
accomplish the same tasks. Put another
way, instead of being able to drive 400 miles to the gallon, now your car can
go 500 miles to the gallon. This is a
positive thing and a preferred state that most people looking to lose weight do
not want to hear because they are preoccupied with counting calories. When you look at the amount of calories you
need to either cut out of your diet or burn just to lose 1 pound of fat you’ll
probably faint.
Burn as many calories
as you can
How many calories do you need to burn to lose a pound of
fat? I’m sure all of you have been given
an answer by either your trainer or doctor, but I can assure you that the
number you were given wasn’t accurate.
Most people were never fans of word problems as kids, and they typically
carry that distaste in to adulthood. If
you look at the questioned I posed, I asked how many calories you need to burn
to lose 1 pound of fat. Your answer was
probably 3500, which is basically the number of calories in a pound of
fat. The problem with this is that it’s
not the question I asked. You see, while
there are indeed 3500 calories in a pound of fat, you are never burning 100% of
your calories from fat.
The largest percentage of calories from fat your body will
use for fuelvis 60%. I will not bore you
with the math, but this puts the MINIMUM number of calories you need to
burn to lose a pound of fat at 5833.
Just to give you an idea, a 160lbs male would need to run at 8mph for 7
hours to burn a pound of fat at that rate, a 7.5 minute mile. Mucking up your long distance running plans
even further, your body burns the highest percentage of fat at rest and it
drops as the intensity of your exercise increases. So, as you pick up the pace, you are burning
a smaller percentage from fat, increasing the number of calories you need to
burn to drop a pound of fat if you are merely concerning yourself with calories
in vs calories out. I would love to tell
you this is the only problem with long distance running or chronic cardio, but
it’s not. Actually, that’s a lie, I hate
long distance running and the fact that it is unnecessary is why I don’t do
it. You see, there has been a
significant amount of research in this area for quite some time and all of it
has shown that high intensity training outperforms long distance, low intensity
training for fat loss as well as markers of carbohydrate and fat metabolism(4,
5, 6, 7)). The most telling study took
place in 1994 by Tremblay, et al. This
study showed that when matched calorie for calorie, high intensity interval
training led to a 9x greater reduction in body fat than did running at a
constant pace (7). How can that be, a
calories is a calorie, right? While that
is true, your body is not merely a machine that burns fuel, it’s quite a bit
more complicated than that. In Part 2,
we will go over the human machine in more detail.
Carbohydrates are the body’s preferred fuel source
This one is actually one of the easier myths to refute
because the science it is based on is foolish.
The reason given for carbohydrates being the body’s preferred fuel
source is that they are metabolized first.
The problem with this is they aren’t.
If you put fats, proteins and carbohydrates in to the body the
carbohydrates will convert to glucose which will be used first. If you add alcohol in to the mix alcohol is
actually metabolized first, and I am going to go out on a limb here and say
your doctor is not going to say alcohol is your body’s preferred fuel source.
If you recall from the calorie is a calorie section, alcohol
aside, the energy sources from food actually have very specific attributes that
lend themselves better to particular needs.
Recall that glucose, the primary substrate from carbohydrate, provides a
moderate amount of energy quickly while fatty acids from fat provide a lot of
energy but at a slower rate. I suppose a
good metaphor is that glucose is jet fuel while fatty acids are more like
diesel fuel. For the most part, the
obesity epidemic is primarily driven by people eating a jet fuel diet while
living a diesel fuel lifestyle. Putting
jet fuel in a diesel engine would cause the engine to run hot and blow out, in
humans it tends to cause a hormonal response that leads to fat gain and,
eventually, obesity. This is because the
human machine has a few things that separate it from the engine. However, the running hot analogy does hold
true for the human body as that is precisely what happens in Type 2 Diabetes.
Another case against carbohydrates being the preferred fuel
source is our limited ability to store it.
A well trained athlete can store approximately 500g of glycogen (The
storage form of glucose), or 2000 calories.
A 160lbs male with 15% body fat has 9,333g of stored energy as fat,
which accounts for 84,000 calories. For
glucose containing carbohydrate being the body’s preferred fuel source, we sure
are lousy at storing it. Our glycogen
stores are enough to power the body for about a day whereas you could run on
your fat stores for weeks. Add to this
the fact that excess carbohydrate will convert to fat while excess fat will
only be stored as fat, and the grounds that “Carbohydrate is the body’s
preferred fuel source” is on is shaky, at best.
Whole grains are good for you
Who on the planet has not heard the term heart-healthy whole
grains? Few actually know this, but there
are quite a few reasons why whole grains are not good for you. Since we are dealing with fat loss, we will
not go over the fact that they bind nutrients and possibly prevent you from
absorbing them(8, 9, 10, 11). We will
also skip over the fact that grains contain storage proteins such as gluten
that are a problem for a lot of people. For
the purposes of this article we will only concern ourselves with the flawed
research used to manipulate you in to thinking whole grains are healthy as well
as their impact on energy.
Just to knock the research portion out of the park right
away, 100% of the research showing whole grains to be healthy doesn’t actually
show that. There have been 3 studies
that I am aware of that directly compare whole grains to not eating grains at
all, and the no grain group in each study had healthier outcomes (12, 13, 14). In addition, an older study showed complete
remission of Type 2 Diabetes in a group of Australian aboriginals that reverted
back to their traditional, grain-free hunter/gatherer diet (15). All of the studies that show whole grains to
be “healthy” have compared them to refined grains, which we know are not
healthy. So do those studies really show
whole grains to be healthy, or do they just show them to be healthier than
refined grains? Put another way, if I
ran a study that showed crack to be healthier than heroin, would that study
show crack to be healthy? I rest my case
on that one.
Outside of the aforementioned issue with nutrient binding
which is certainly not a trivial issue, whole grains are a large source of
carbohydrate. Since these carbohydrates
will eventually be broken down in to glucose, they will provide a quick source
of energy. This is actually not a bad thing
if you are someone who needs quick access to energy like a day laborer or an
athlete, but if you are sitting on your rump all day long you are certainly not
in need of quick access to energy.
Your doctor may have explained to you that the glucose from
whole grains enters your bloodstream more slowly than, say, table sugar. What he or she may have failed to mention is
that 2 slices of whole grain bread will eventually dump the equivalent of 5
teaspoons of table sugar in to your bloodstream. Add in a serving of pretzels and you are
dealing with about 10 teaspoons of table sugar.
Just for comparison’s sake, your entire blood volume holds just a hair
under 1 teaspoon of glucose at a time.
No matter how you swing it, that is a ton of fast acting energy that a
sedentary person does not need so they are more than likely going to store it
with the help of a hormone called insulin.
Humans are
biologically driven to seek food and expend as little energy as possible to get
it, and this is driven by hormones.
Thanks to evolution via natural selection, a majority of us are
engineered perfectly to eat as much as possible when the opportunity presents
itself because it has been scarce for the vast majority of time. Insulin allows us to store fast acting energy
for a time when we will need it, a fact most people know. From this point of view, we no longer need
insulin for energy storage since we are in an environment where food is
plentiful and there is no need to expend energy to get it. However, when you look at it from a blood
glucose point of view, insulin is actually trying to pull glucose out of your
bloodstream as fast as it can because high levels of blood glucose are very
damaging to your blood vessels and organs.
Our hormones make us ill-suited to our current environment.
In Part 2 we will examine how our metabolism works and things that
we should be doing to keep it working properly.
References
1.
Gornall J, Villani, RG. Short-term changes in
body composition and metabolism with severe dieting and resistance exercise. Int J Sport Nutr 1996; 6:
285–294.
2. Johansen,
DL, et al. Metabolic
Slowing with Massive Weight Loss despite Preservation of Fat-Free Mass. The Journal of Clinical Endocrinology
& Metabolism April 24, 2012 jc.2012-1444.
3.
Thompson JL, Manore MM, Thomas JR. Effects of
diet and diet-plus-exercise programs on resting metabolic rate: a
meta-analysis. Int J Sport Nutr 1996; 6: 41–61.
4.
Boutcher SH. 2011. High-intensity intermittent exercise and fat
loss. J Obes.
2011:868305. Epub 2010 Nov 24.
5.
Perry CG,
Heigenhauser GJ, Bonen A, Spriet LL. 2008 High-intensity
aerobic interval training increases fat and carbohydrate metabolic capacities
in human skeletal muscle. Appl
Physiol Nutr Metab. Dec; 33(6):1112-23.
6.
Talanian JL,
Galloway SD, Heigenhauser GJ, Bonen A, Spriet LL. Two
weeks of high-intensity aerobic interval training increases the capacity for
fat oxidation during exercise in women. J
Appl Physiol. April, 2007;
102(4):1439-47.
7.
Tremblay
A, Simoneau J-A, Bouchard C. Impact of exercise intensity on body fatness and
skeletal muscle metabolism. Metabolism. 1994;,43(7):814–818.
8.
Bohn T, et al. 2004. Phytic
acid added to white-wheat bread inhibits fractional apparent magnesium
absorption in humans. American Journal of Clinical Nutrition. 2004
79:418-23.
9.
Navert B and
Sandstrom B. Reduction of the phytate content of bran by leavening in bread and
its effect on zinc absorption in man. British
Journal of Nutrition 1985 53:47-53.
10.
Singh M and
Krikorian D. Inhibition of trypsin activity in vitro by phytate. Journal of Agricultural and Food Chemistry
1982. 30(4):799-800.
11.
Tannenbaum and
others. Vitamins and Minerals, in Food Chemistry, 2nd edition. OR Fennema, ed.
Marcel Dekker, Inc. New York, 1985, p 445.
12.
Frassetto LA, Schloetter M, Mietus-Synder M,
Morris RC, Jr., Sebastian A: Metabolic and physiologic improvements from
consuming a paleolithic, hunter-gatherer type diet. Eur J Clin Nutr 2009.
13.
Jonsson T, Granfeldt Y, Ahren B, Branell UC,
Palsson G, Hansson A, Soderstrom M, Lindeberg S: Beneficial effects of a Paleolithic diet on cardiovascular risk
factors in type 2 diabetes: a randomized cross-over pilot study. Cardiovasc Diabetol 2009, 8:35.
14.
Lindeberg S, Jonsson T, Granfeldt Y,
Borgstrand E, Soffman J, Sjostrom K, Ahren B: A Palaeolithic diet improves
glucose tolerance more than a Mediterranean-like diet in individuals with
ischaemic heart disease. Diabetologia
2007, 50(9):1795-1807
15.
O’Dea K: Marked improvement in carbohydrate
and lipid metabolism in diabetic Australian aborigines after temporary
reversion to traditional lifestyle. Diabetes
1984, 33(6):596-603.
