Newbie

Scott - somewhat long-winded, forgive me.

To answer your question directly, macros (carbohydrates, proteins, and fats) are the basic building blocks used by the body to fuel various functions.  Our body prefers carbs as they’re ‘easier’ to process, but can also burn fat.  Proteins fuel various ‘systems’ such as muscles, organ functions, etc.

I’ve read a lot since starting this back in mid-October.  It’s somewhat long winded, but I’d like to give a good summary of my experience and hope that it might be beneficial.

Ketosis is a result of limiting carbs to somewhere between 20 and 50 carbs.  My personal opinion is the lower the better.

Stay under your carbs (they’re a limit), meet your proteins (they’re also a limit so be very careful not to exceed them) and stay under your fats at first.   As you lose stored body fat and approach your weight goal, you’ll need to up your dietary fat intake in order to meet your fat macro in order to maintain your weight and sustain yourself, but you’ll realize that as you get there.

The body requires a certain amount of energy to sustain it.  This energy can come from burning either carbohydrates or fat.  The less carbs we eat, the more fat we force our body to burn.  It’s a zero-sum game; less carbs to burn means more fat has to be burned to keep us going.  And within fat, the body burns a combination of what we eat (dietary fat) and what is stored (adipose fat); there’s a constant ‘churn’ of dietary and adipose that’s cycled into the fat burning process. 

Indeed, from the Virtahealth website’s (more on that below), is the following FAQ:  Is dietary fat burned before stored fat on a ketogenic diet?  Answer: ‘Certain fats, like medium-chain triglycerides found in coconut or MCT oil cannot be stored in body fat, so whatever is consumed must be promptly burned for energy. This means that if you’re adding these fats on top of your dietary fat consumption for satiety, this type of fat takes priority.

For regular dietary fats, once they are digested, they enter the circulation and participate in what is called ‘fatty acid turnover.’ Whether fed or fasted, the body is always releasing, burning, and storing fat. When insulin is high, storage predominates, but turnover continues. When insulin is low, release and oxidation predominate. If you eat fat along with a lot of carbohydrates, it is prone to be stored. When fat is consumed in the context of a well formulated ketogenic diet, it—along with fat released from adipose stores—is prone to be burned. But once digested and absorbed, dietary fat and stored fat enter the ‘turnover pool’ and are in a constant state of mixing.’

But it’s still a zero-sum game.  If, as a very fictional example, let’s say the body requires 100g of fat each day.  It will burn 100g’s from the fats in circulation as described in the FAQ above.  But if you eat 40g of dietary fat, all you’ve done was replace that amount.  Think: burned 100g but replaced 40g for a net loss of 60g.  To lose weight in keto, you’ll need to stay below your fat macro so you’re in a ‘fat deficit’.  How much depends on the individual, but to a point I think the further below, the more the body runs at a fat deficit and the higher the weight loss.

Looking at proteins, you don't want to exceed your protein macros by too much or too often.  Indeed, the protein macro is pretty much a constant throughout the keto process.  From Virtahealth, most healthy humans maintain lean body mass and function during a ketogenic diet providing between 1.5 and 1.75 grams of protein per kg of ‘reference body weight’.  (Reference body weight is an arbitrary value for men and women based upon the medium frame values from the 1959 Metropolitan Life Insurance ‘Ideal Body Weight’ tables. (Met Life, 1959) Using these values allows for protein intakes to be based roughly on normal lean body mass rather than total body weight. Note: ‘reference weight’ is an arbitrary value used to estimate daily protein needs—it is not a weight).

You can also get a very close approximation by using Body Mass Index (BMI) of your TARGET weight goal (NOT your starting weight).  I’ll use myself as an example.  I’m 6’1” and started this keto journey at 265-lbs.  My target weight was 200-lbs (purely arbitrary, but it’s what I used to weigh back in the Marine Corps).  Googling ‘BMI’ and looking at the resulting table, the BMI for 6’1” and 200-lbs is 26% (note: 26% body fat is still considered overweight, but it’s much better than the BMI of 35% (obese) I started at!)  Anyway, 26% of 200-lbs gives me 52-lbs of body fat, which when subtracted from my total goal weight (200-lbs) gives me a lean body mass of 148-lbs (total body weight (200) minus body fat (52) equals lean body mass (148).  Converting pounds to kilograms (divide by 2.205) gives me my reference lean body mass of 67.12kg.  And using the formula above (1.5 to 1.75 grams per kg reference body weight) my protein macro should be between 1.5 and 1.75 grams times 67.12, or between 101 and 117 grams per day.  I selected 101 grams and it’s been working fine.  Again, it’s a stable number: ‘set it and forget it!’

In the experience of Drs Phinney and Volek (see last paragraph below), people on a ketogenic diet who think they are eating protein in moderation are often well above 2 g/kg due to fear of eating fat to satiety.  That’s not good as excess proteins are converted to sugars and that’s just like excess carbs; more carbs to burn means less fat burned and it can drive fat into storage thus increasing weight.  Proteins power muscles, organs, etc. so you don’t want to short them by too much or too often - bodily ‘systems’ start to degrade very quickly without sufficient proteins.  

So (I believe) the best way to generate healthy benefits (lower blood sugar, weight loss, etc) is to cut back on carbs (we’re all different but as an example, my personal limit is 12g/day in order to keep my blood sugars down) and keep things at or just below proteins to properly power body systems.  As for fats, they’re not really a goal or objective.  Again, a combination of both dietary fats and adipose fats are burned.  Less dietary fats eaten maintains a fat deficit which results in more adipose fats burned, particularly at the beginning when we might have more stored fats to burn.  As the weight comes off and the health improvements take place, you can up your dietary fats since there’s less stored fat to burn.

Last, a lot of folks want to take what I think is the quick way - still want their shakes, bagels, buns, cakes, etc.  Just because something is labeled ‘Keto’ (as is quite often the case out on Pinterest), it doesn’t mean that it is, only that somebody’s doing some clever (or nefarious) advertising.   My readings suggest it’s best to stick to ‘real’ foods: beef, chicken, fish, pork, with fresh vegetables and salads.  (I come to tell myself that ‘Keto junk food’ is still junk food.)

There are some great books out there, and I’d highly recommend ‘The Art and Science of Low Carbohydrate Living’ by Drs Jeff Volek and Stephen Phinney. They’re also on YouTube, and you can google Virtahealth to find their business (I’m NOT a customer) where they have a plethora of medical case studies to back up what they say - either way, they can explain things very well and give all the medical science behind the scenes.  And don’t forget the information found right here on the Carb Manager app (under the ‘Learn About Keto’ tab or the excellent .pdf file found in the ‘KetoGenius Diet Plan’.  Both are excellent.

I hope this helps.