While exploring the Very Low Carb world over the years, I have
been interested in the workings of both Macronutrient Ratios and Ketogenic
Ratios. I started with the study of Macronutrient Ratios soon after I realized
that “counting carbs” was not enough. I added protein and then fat (and total
calories) and adjusted them over the years to where I have now settled on 75%
fat, 20% protein and 5% carbs, on only 1,200 calories a day. This calculates to
a ketogenic ratio of about 2.0. More on these values later.
Of course these Macronutrient
ratios account for only ingested food – food and drink that I put in my mouth.
But since I strive to eat so few carbs, when
I am not eating too many carbs
or too much fat (and protein),
I am able to add to the calorie burn – what my body requires to maintain energy
balance and an active
metabolism – by burning body fat. I know that I have access to these fat
calories because my serum insulin levels remain fairly low because there is a
correspondingly low level of glucose circulating from both carbohydrate and
protein restriction. I know that my body is not shutting down – or even
slowing my metabolism to compensate for the low calorie intake by mouth – because
I feel “pumped” all the time.
This additional fat burning would
imply that my actual Macronutrient Ratios are higher than 75/20/5. It also
would imply a higher Ketogenic Ratio, since only fat is being added to the
equation, almost all in the numerator.
So, let’s do the numbers. If
my daily food intake is 1,200 calories, and the Macronutrient Ratios are 75%
fat, 20% protein and 5% carbs, my intake is composed of 100g of fat (900kcal),
60g of protein (240kcal) and 15g of carbs (60kcal). But if my metabolism stays
up, that is, is not slowed down by the lower food intake – because the low carb intake allows my body access to its fat stores
– then
my actual fat contribution, at the cellular level where
the nutrients are absorbed, is going to be much higher. How much
higher, you ask?
That depends on my metabolic
rate. How many calories does my body burn?
That would be the sum of my resting metabolism plus activity level, when
not slowed down by either calorie restriction or from blocked access to
fat stores.
Let’s say, for argument’s sake,
that my metabolism chugs along at 2,550kcal/hr. If I am only taking in (by
mouth) 100g of fat, 60g of protein and 15g of carbs, it is theoretically
getting a contribution from body fat of 2,550 – 1,200 = 1,350kcals, or another
150g of body fat (1,350kcal/9kcal/g = 150g). That substantially changes the
Macronutrient Ratio at the cellular level, where the body is actually fed. Check
out this chart:
Nutrition
& Metabolism
|
kcal
|
fat(g)
|
pro(g)
|
carb(g)
|
k/g ratio
|
Intake orally (food my mouth)
|
1200
|
100
|
60
|
15
|
2.0
|
Intake at the cellular level
|
2550
|
250
|
60
|
15
|
3.5
|
The formula for ketogenic ratio is derived from the work of Wilder
and Winter (1922):
K/G ratio = (0.9*FAT+0.46*PRO)/(0.1*FAT+0.54*PRO+1*CHO.)
N.B.: Ideally, I am
only burning extra body fat – and sparing protein. My body will use
the carbs that I ate, which are going to be oxidized first, when it needs to
make glucose for those cells that do not have mitochondria and therefore lack
the ability to make ATP. Plus, amino acids from digested protein, not taken up in
circulation, will become glucose via gluconeogenesis in the liver. And, the
liver can also make glucose from the glycerol backbones of catabolized
triglycerides when body fat is broken down and burned.
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