Quick Bites: Ketosis and Protein

Hi guys! As I was writing the previous instalment of my little “decoding ketosis” series (btw – WOW! thank you for all the love!), I realised something; I’ve talked quite a bit about minimising carbohydrate intake, and burning fat, but I haven’t really spoken much about the role protein plays in ketosis. So, today’s post is a short one, covering just that.

First, A Whoopsie!

I’m awfully sorry, but I have discovered that I actually made a technical error in my previous posts, and the nerd inside me simply won’t let me breeze past it – allow me to confess my sins and correct my errors. I have been using the term “ketones” to describe the molecules produced by the liver – this is technically incorrect. Typically, the term “ketone” refers to a molecule where a carbon atom is sandwiched between two other carbon atoms, and double bonded to an oxygen atom. (Yes, we’re getting down to the atomic level here – this stuff is HARD!). “Ketone bodies”, on the other hand, is the correct term for the three specific molecules (acetone, acetoacetone/acetoacetic acid, and beta-hydroxybutyrate/beta-hydroxybutyric acid) – only the first two are actually “ketones” in the technical sense. It’s a common mistake, but one I need to correct if I want to maintain a modicum of credibility :) So, henceforth, I will be using the correct terminology – my apologies for misleading you all!

Right, now, down to business.

To Reiterate…

If we go back and look at my first post in this series, we can see a bit of a breakdown of the recommended macronutrient ratios for nutritional ketosis: roughly 65% fat, roughly 30% protein, and about 5% carbohydrate. This is a high-fat/moderate-protein/low-carbohydrate approach. It’s pretty obvious why we have to keep carbohydrate so low (because otherwise the body switches back to a “sugar burning” metabolism), and eating fat simply provides the body with more of the fuel that it’s using… But why would we stick to “moderate” protein? Why not more of it? Why not less?

Here’s Why

Protein plays an important role in nutritional ketosis, and one must maintain a very delicate balance with dietary intake.

Ketosis, as a metabolic state, is “muscle sparing” – i.e., it helps maintain lean body mass (muscle and bone). Your body is capable of breaking down muscle into proteins that can be used for energy. When you get the balance right, this doesn’t happen on a ketogenic diet – proteins no longer compete with fatty acids for energy utilisation (fat is the primary energy source, it “wins”), and muscle mass is largely spared.

However, there are some problems with eating both too much and too little protein in this type of approach – and this is where things get tricky.


We’re introducing a new word to our ketosis vocabulary. “Gluconeogenesis” literally translates as “making new glucose” (gluco = glucose, neo = new, genesis = the making). In this process, other substances are converted into glucose in the liver and the kidneys. Setting ketosis aside for a second: If glucose requirements are high (say, we’re exercising hard), but glucose availability is low (say, we haven’t eaten for 24 hours), our bodies will break down muscle (which could be considered our “protein stores”), and use the process of gluconeogenesis to transform that protein into the glucose we need.

Back to ketosis: Our bodies will always have a small glucose requirement – always, even if we’re the most ketogenically-adapted individual in the history of nutrition. Seeing as we’re probably not getting that from our low-carbohydrate ketogenic diet, our bodies will use the process of gluconeogenesis to make up the deficit. If we don’t consume any protein, our bodies will have to take the protein to fuel this process from our muscles, breaking down our lean body mass – we certainly don’t want that. The way to stop our muscles being broken down this way is to eat enough protein to repair the muscles as necessary, and support gluconeogenesis.

However, if we eat too much protein in a ketogenic diet, ketosis may be halted. We will use the excess protein for additional gluconeogenesis, which will push our blood glucose up, which will signal our body to make the switch back to sugar burning – just like eating too much carbohydrate would.

See what I mean when I say it’s tricky?

Ultimately, Here’s What You Need To Know

Eating an adequate amount of dietary protein will allow you to maintain ketosis, while simultaneously preventing the breakdown of muscle. Your body would really rather use dietary protein to meet its glucose requirements. Bear in mind, too, that your body becomes very efficient in a ketogenic state, and reduces its glucose requirements altogether – so less and less protein is required for gluconeogenesis.

Ultimately, at least some of the protein that you consume will end up in your bloodstream as glucose, which raises insulin levels, and so on and so forth. This is normal, and necessary. However, this also means that protein must be restricted to some degree, as an excessive intake will generate too much gluconeogenesis. The only way to find your “sweet spot” in between these two extremes is personal observation and testing – trial and error. It’s different for everybody, based on age, size, existing muscle mass, goals, activity levels, etc.

Adequate dietary protein is essential to maximising fat loss and minimising muscle loss, whatever nutritional approach you take – it’s just a little harder to find the perfect “zone” with a ketogenic diet, given the delicate balance you’re operating in.

And, P.S., it’s important to remember that any intake of carbohydrate (even a few extra leaves of spinach) will decrease the demand for gluconeogenesis, which will decrease your protein requirement accordingly. Just to make things even more complicated!

Have you tried a ketogenic diet? How did you approach the protein issue? What do you think about this nutritional ketosis series so far? Anything you’d like me to add?

2 thoughts on “Quick Bites: Ketosis and Protein

  1. Hey, I’ve really enjoyed reading these “series”! I’m just getting started on my weight loss and your blog inspired me to start up my blog. Keep it up!

    • Hey, that’s awesome! I’m glad you’ve enjoyed it! Be sure to stay tuned, because I’ve got a lot more coming up :) And do give me a holler if you have any questions or anything you want to chat about, I’m always up for it! :D

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