Today, I want to chat briefly about the concept of Macronutrient
Partitioning.
This refers to the
breakdown (percentages of total calorie intakes) of carbohydrates, proteins and
fats that we eat. This is a general overview of the topic. If you want more details, I would suggest that you check out this blog post on
Robb Wolf's site and consider this ebook, which is very well researched and describes the topic in quite easy and practical terms, it's called
carb backloading.
Why consider this? Simple. If how much we
ate was the only driving force, then circulating hormone levels would not need
to be considered. This is NOT the case,
and as you will see, macronutrient composition can alter hormonal circulatio, which then can determine how the macronutrients are utilized in the body.
All macronutrients are necessary for overall health, optimal
performance and maximal longevity! Here
we look quickly at the role of each macronutrient in the body.
1) Carbohydrate.
This category of nutrient is primarily used for energy.
Interestingly, the body has the ability to
create carbohydrates given the right substrates and it can adapt to ketone
bodies as fuel as well. This category includes mainly fibre, starch and
sugar.
Fibre is primarily indigestible
although some has been shown to be broken down by bacteria in the colon to
release fatty acids for fuel.
Sugar is
the simplest form of carbohydrate energy and is quickly absorbed and enters the
blood as glucose.
Table sugar is
actually sucrose which is a 50/50 blend of glucose bound to fructose molecule.
Fructose is preferentially stored in the
liver and has been shown to lead to central adiposity.
The structure of glucose is shown to the right
and is a primary fuel source for anaerobic activity (think high intensity
glycolytic activities) via glycolysis and Kreb’s cycle and the electron
transport chain one molecule of glucose directly creates a net of 2 ATP (energy
molecules).
Glucose is blood sugar and entry
of this into the blood stream stimulates secretion of insulin by the pancreas
to regulate the circulating levels of this in the blood (CITE).
Most food labeling requires sugar be listed
because of its rapid effect on blood sugar (and insulin) levels, however, a
large amount of starch, although not as rapid-acting can definitely raise blood
sugar (and insulin) for longer periods of time, which can change structure of
adipose tissue to become more efficient at storing fat (vs. burning it).
2) Protein. These are essential nutrients for the body,
as they are building blocks of every tissue and are also used for energy
sources. Certain amino acids are
essential as humans cannot synthesize them; all others can be made from the
essential ones or by breaking down ingested proteins. Conditional amino acids are not usually
necessary except during times of stress, illness and specific inborn errors of
metabolism. By far the best biological
availability and quality of proteins are found from animal sources. Vegetarian options can suffice but are less
than optimal. Branched chain amino acids
can be broken down into Acetyl-CoA and Succinyl CoA and enter Kreb’s cycle to
produce energy as the body requires.
3) Fat
(Lipid). This group includes fats, waxes, sterols, fat-soluble
vitamins (A,D,E,K), mono-, di- and tri-glycerides, phospholipids and
others. Their main roles include energy
storage, signaling and structural components of cell membranes. Fats provide the richest source of energy for
aerobic respiration, in which two carbon units of fatty acids are released and
enter Kreb’s cycle and subsequently the electron transport chain to create
energy (i.e. palmitate (C16:0) oxidation results in 106 ATP (13.25 ATP per
2-carbon chain)).
We need to
understand the effects of each macronutrient profile on hormone secretion and
subsequently on body composition.
A)
High
carbohydrate, low fat: This is
the USDA, HC norm and given today’s sources of carbohydrates (i.e. highly
refined) has been associated with increases in insulin (to the point that the
body can become resistant insulin resistant) and increased body fat particularly around the
abdominal area (i.e. surrounding the visceral organs). This is the most dangerous form of obesity
and is directly associated with metabolic syndrome.
Elevated
insulin:
-
Promotes
fat storage and stops fat burning.
-
Promotes
protein synthesis and decreases protein hydrolysis.
-
Therefore,
it promotes growth of both fat & muscle tissue.
-
Can
cross the blood brain barrier and when dysregulated it has been implicated in
neurodegenerative diseases (i.e. Alzheimers) and psychiatric disorders (i.e.
Schizophrenia).
B)
High
fat, low carbohydrate: This is
a ketogenic diet. It can take up to 4
weeks for the body to adapt to ketone bodies as a primary fuel source. This directly oxidizes and burns stored body
fat. Circulating insulin levels are low
and therefore the body is shifted into fat burning mode away from fat storing
mode. Many different tweaks have been
shown to improve fat burning ability and further hamper fat storing expression
(i.e. exercise type & volume, timing and amount of carbohydrate intake, amount
and type of protein intake, etc…).
Therefore, it would
seem that for optimal health, performance and longevity we would be best served
by doing the following.
1)
Protein:
a.
Aim for
around 1 g/ lbs of your ideal body weight daily
b.
Choose
the best sources (animal vs. vegetable; grass fed vs. grain fed; consider fats
included with protein)
2)
Fats:
a.
Aim for
2 g/day of omega-3 (DHA + EPA combined).
b.
Not more
than 8 g omega-6 per day.
c.
Get
adequate monounsaturated fats (olive, avocado, hazelnut and macadamia nut and
oils).
d.
Saturated
fats (animal sources + coconut oil).
When carbohydrates are lower, these can be your primary fat
sources. These are the most stable for
cooking and least oxidizable.
3)
Carbohydrates:
a.
Keep
your total intake to around 100-150 g per day (depending on your body
composition goal).
b.
Eliminate
sugar and refined grains (i.e. all grains are refined).
c.
Consume
your main carbohydrate loads post workout (especially strength training) up to
4 hours after and focus on starchy vegetable carbohydrates primarily.
Citations
