Let me preface this post by saying everything I’ve ever learned about setting macros comes from (a) Dr. Stephen Phinney, and (b) trial and error.
I trust Phinney because he’s been researching ketogenic diets long before the Kardashians made it popular, and he doesn’t peddle any special weight-loss programs or supplements. I use his guidelines as a starting point, and make adjustments as per my own individual experience.
If you want to go straight to the source (and for a more technical explanation), I highly recommend his article on how to formulate a ketogenic diet, co-authored with Jeff Volek and Brooke Bailey.
KETOSIS EXPLAINED
As outlined in a previous post, there is a big difference between a low-carb diet and a ketogenic diet. The production of ketones is key to preventing migraines, and a whole host of other neurological disorders. Arbitrarily reducing carb intake doesn’t necessary lead to ketosis.
Ketones are produced by the liver when insulin levels are sufficiently low. The ketone molecule consists of three compounds: acetoacetate, acetone and beta-hydroxybutyrate (BHB).
BHB supplies energy to the brain in the absence of glucose, and is the key molecule credited for the treatment and prevention of neurological diseases, including depression, migraines and epilepsy.
In order to be in ketosis, the concentration of BHB in the blood needs to be between 0.5 and 4.0 mM (nanomoles per litre).
Therefore, a properly formulated ketogenic diet requires the following:
- a carbohydrate intake low enough to ensure the production of ketones
- sufficient protein to repair, maintain and grow your muscles
- enough fat to satisfy your daily caloric needs.
Those three components (carbs, protein and fat) make up your daily macronutrients[1], and those limits vary greatly from person to person.
THE STARTING POINT
In order to figure out what your daily macros should be, there are a few things you need to know:
- your Basal Metabolic Rate (BMR)
- your daily activity levels
- your goals (weight loss/gain or maintenance).
Your basal metabolic rate is the amount of energy required for your body to properly function at rest, including breathing, blood circulation, digestion and cell regeneration. Metabolism varies by gender, size (height and weight), age and lean body mass.
Knowing your BMR gives you a starting point. You then add daily activity levels to get your Total Daily Energy Expenditure (TDEE). Note that TDEE estimates are wild-ass guesses, since there are many external factors that determine your metabolism, including body composition, sleep, stress levels, hormones and genetics. Fudge factors for activity levels are also very subjective, so your calculated daily energy requirements are just very rough estimates.
Once you know (or have a good estimate of) your TDEE, you set your daily macros according to your goals.
The next set is to figure out where these calories will come from － carbs, protein, dietary fat or body fat (ketones)[2].
NOTES:
¹ Since ketones provide an alternate energy source for the brain, they are sometimes referred to as the fourth micronutrient.
² It’s worth repeating, body fat can only supply energy if you’re in ketosis. That’s why calorie restriction alone doesn’t necessarily lead to fat loss.