Retrospective #354: Macro and Keto Ratios

While exploring the Very Low Carb world over the years, I became interested in the workings of both Macronutrient Ratios and Ketogenic Ratios. I started with the study of Macronutrient Ratios around 2006 when I thought that “counting carbs” was not enough. I added protein and then fat (and total calories) and adjusted them over the years to where I eventually settled on 75% fat, 20% protein and 5% carbs, on only 1,200 calories by mouth a day. This calculates to a ketogenic ratio of food by mouth of about 2.0. More on that 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 – when my body requires more to maintain energy balance and remain an active metabolism – by burning body fat. I know that, so long as I eat Very Low Carb, I will 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 carbohydrate (and protein) restriction. I know that my body is not shutting down – or even slowing my metabolism down to compensate for the low calorie intake by mouth – because I feel “pumped” all the time.

This additional body 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 for food by mouth 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 my activity level, when not slowed down by either calorie restriction or from blocked access to body 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 (1,200kcal total), it is theoretically getting a contribution from body fat of 1,350kcal (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)	cho(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 Wilder and Winter (1922):

K/G ratio = (0.9*FAT+0.46*PRO)/(0.1*FAT+0.54*PRO+1*CHO.) 3.5 is a solid ketogenic ratio.

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 will also make glucose from the glycerol backbones of catabolized triglycerides when body fat is broken down and burned. So, fundamentally, the body’s requirement for carbohydrates is zero.