The Cyclical Ketogenic Diet (CKD)

Last modified on September 22nd, 2013

Cyclican Ketogenic Diet

Cyclical Ketogenic Diet (CKD), photo from Wikipedia

It’s no surprise to anyone reading my site that I’m a big advocate of reducing carbs. Pretty much everything out there nowadays is full or both refined carbohydrates and sugar, often in the form of high fructose corn syrup. While complex carbohydrates aren’t that bad for a person, anything that converts immediately into glucose (such as simple carbs and sugars) can cause large insulin spikes, leading to fat gain and ultimately diseases such as diabetes.

Unfortunately there’s so much misinformation in this area that most people are completely confused about carbohydrates, insulin, and most other areas in the realm of food and nutrition.

Despite what most nutritionalists will tell you, the body can work just fine without carbohydrates. In fact, about five years ago I did a little experiment where I reduced my carbohydrate intake to around 20 grams a day for around four months. Not only did I feel better, but I also lost almost 40 lbs, all without going to the gym.

The body stores carbohydrate internally as glycogen. Glycogen can be readily broken down and converted into glucose to meet the energy needs of the body. For every one gram of glycogen stored, the body requires 3-4 grams of water. That’s why most people seem to lose a few pounds of weight immediately starting any diet (more pronounced on a low carb diet) — the extra weight is the body shedding the water that was used to bind the glycogen. It’s also a sound bite that most people on TV use to try and discredit low carbohydrate diets — that the weight lost is simply water. That’s true of course, but it’s also true of any other diet. If you lose 20 lbs on a low-carb diet, and then carb back up again, you’ll probably gain about 5 lbs as water is rebound to glycogen, but you still will have lost 15 lbs of fat.

When carbohydrates are restricted from the body, glycogen will be utilized to fuel cells within the body. When glycogen runs out (usually without about 24 hours or so), the body will then look to the fat cells to try and make up the energy deficit. While some organs in the body can use free fatty acids directly, other organs, such as the brain, can’t (free fatty acids are too large to cross the blood/brain barrier).

The body then converts free fatty acids into ketone bodies, which can be utilized by many organs in the body, including the brain and heart. While the brain will eventually derive 70% of its energy from ketone bodies, the glucose that it does require can easily be made within the body by a process called gluconeogensis.

There are debates in the research world about whether a diet completely lacking in carbohydrates can still make an athlete competitive. Most research seems to show there’s a definite degradation of performance in the short term, but after about two weeks or so, the difference in athletic performance on a low-carb diet vs a high-carb diet is negligible.

That said, there are a few sports/activities where having a readily available supply of glucose is an advantage, such as weight lifting. Weight lifting is an anaerobic activity that requires short bursts of energy. As converting fat into usable energy is arguably a slower process that utilizing glucose, many athletes prefer to have a limited glycogen store for work outs, even while maintaining a low-carb diet.

A particular diet was developed a few years ago to try and address these concerns. That is, how you can adapt a low-carbohydrate diet to someone that also wants to be able to perform at 100% in the gym, and also lose weight in the process. One such diet is called the Cyclical Ketogenic Diet (CKD).

Any diet that forces the body to produce ketones from fat is called a ketogenic diet. Ketogenic diets (which cause insulin levels to plummet) have actually been used for years to treat several ailments, including epilepsy when it doesn’t respond to medication. They also have the advantage of causing people to readily lose fat, since fat storage cannot take place when insulin is lacking. Atkin’s is a ketogenic diet, as are most diets that include less than about 50g of carbs per day.

The main premise behind the cyclical ketogenic diet is to adhere to a high-fat, moderate protein, low-carb diet during the week, but allow yourself one large cheat day each week. On the cheat day (usually on the weekend), the goal is to replenish all the glycogen in both the muscle in the liver such that they can be drawn upon over the course of the week for performance in various anaerobic activities, such as weight lifting. Because glycogen re-synthesis requires carbohydrate, most cheat days are composed almost entirely of carbohydrates (i.e. beer, nachos, pasta, all great Saturday foods).

Obviously if you go crazy on your cheat day, you’ll not only refill your glycogen stores, but also cause excess energy to be stored as fat. So you have to be conscious of the amount of food you eat such that your glycogen is filled, but not overfilled. But in theory the carbohydrates you eat on your cheat day will be converted into muscle and liver glycogen, while the rest of the body will continue to obtain energy by breaking down fat.

There’s also anecdotal evidence that having a large spike of food once per week limits the body’s ability to down-regulate the basal metabolism, and also stimulates the thyroid gland, which raises metabolism.

Given that I’ve been going to the gym for the past few months, I thought I’d try the Cyclical Ketogenic Diet (also known as the CKD) for a few weeks and see if I feel any difference at the gym. This is basically the end of week one, so I had a cheat day last Friday. From now until Friday, I’ll go back to eating low-carb food choices, which should make it so that I’m back in ketosis again probably tomorrow night.

Tim Ferris (author of one of my favourite books, The 4-Hour Workweek) is an advocate of the CKD, and talks about a modified version on his site.

You can also read a bit more about it in these forums, or do a Google search.

Books About Low-Carb Diets

Here are a few of my favourite books that discuss low-carb diets in general and why they work so well. A low-carb diet is very similar to the cyclical ketogenic diet (CKD), except that the CKD allows a full-on cheap day once a week.

  • The 4-Hour Body: An Uncommon Guide to Rapid Fat-Loss, Incredible Sex, and Becoming Superhuman – Tim Ferris is a huge advocate of the CKD, and he discusses aspects of it in this book, as well or other great tips for improving your body.
  • Why We Get Fat And What To Do About It – my favourite book on food and nutrition is Good Calories, Bad Calories by Gary Taubes. That book is difficult to read though, so the same author created this book to make the material easier. I highly recommend reading this book for anyone who is trying to lose weight or understand carbohydrate metabolism.
  • Wheat Belly – I recently read this book which claims that the modern version of wheat (which is nothing like the wheat that used to be eaten hundreds and thousand of years ago) is one of the main sources of obesity in the world currently.

13 responses to “The Cyclical Ketogenic Diet (CKD)”

  1. Alex Curylo says:

    “Despite what most nutritionalists will tell you, the body can work just fine without carbohydrates.”

    Well, it takes a little attention to where you’re getting vitamins from. I’ve been looking into an approaching zero carb diet myself, and it seems that you’ll need fairly frequent intake of raw liver, raw scallops and raw oysters if you want to cover all your accepted vitamin needs as carnivorously as possible. Fortunately, I rather consider all of those delicacies, going back to when as a little tyke my Polish grandma insisted all of those three were essential to being healthy (plus massive doses of fish oil, but I believe everybody agrees the more EFAs the better these days) and my Scottish mother was horrified at the thought of eating anything not cooked to solidity. Funny how after reading “Good Calories, Bad Calories” and doing my own reading around on the most plausible-sounding nutritional information I can find, I’m arriving at pretty much the exact same diet my no formal education whatsoever Polish peasant immigrant grandmother told us kids we should eat…

  2. Duane Storey says:

    Why not just take a multivitamin?

    Good Calories, Bad Calories is a great book. I’ve actually trade a few emails and a phone call with Gary Taubes, and hopefully will be helping him with his website when the time comes. He has a new book coming out in the near future.

  3. Alex Curylo says:

    “Why not just take a multivitamin?”

    A) There’s been enough exposés on retail vitamins not matching their alleged contents that I don’t think relying on them is a sound strategy

    B) I’m mildly skeptical that anything contained in a pill is actually going to be metabolized the same way as the same anything found in foods our last 19,999 generations of ancestors could have eaten.

    Not that either of these stops me taking a daily broad spectrum multivitamin, and a calcium/Vitamin D pill as well since I don’t get out in the sun enough, but figuring they probably won’t hurt is a big step away from considering them reliable.

  4. Duane Storey says:

    You won’t take a multivitamin, but you take fish oil supplements? 🙂

    Just curious — what vitamins do you think you’ll have a hard time obtaining. If you eat a lot of vegetables, I’d be surprised if you couldn’t hit your recommended intake. Unless your zero carb diet is eliminating all vegetables too, although I don’t see why you would want to do that since most vegetables (other than starchy ones like yams, corn, beans and carrots) hardly produce any insulin response.

  5. Alex Curylo says:

    ” You won’t take a multivitamin,”

    You missed the “Not that either of these stops me taking a daily broad spectrum multivitamin” part?

    “Just curious — what vitamins do you think you’ll have a hard time obtaining”

    phosphorus, potassium, zinc, other trace minerals, some vitamin D and lots of B12 from the shellfish; vitamins A/C/Beverything, folate, copper, selenium from the liver. A varied mix of eggs/cheese/meats seems to cover pretty much everything else important without any particular worry.

    “Unless your zero carb diet is eliminating all vegetables too, although I don’t see why you would want to do that”

    Experimentation, mainly. While running through all my stored foods here, I’ve established that my weight set point is about eight pounds higher with grains than without grains but still significant starchy vegetables. Once the last few packages of corn and peas and the like are gone, I’m planning to switch on a dime to only trace carb foods (to the point of only butter and triple cream brie for dairy products) except for the above-mentioned shellfish and liver, and see what happens to my weight then. Presumably at some point I’ll start adding carbs back in, at least things like nuts and avocado and yogurt and the like. But we’ll see.

  6. Duane Storey says:

    Your weight probably won’t change that much. About 50% of protein also metabolizes as carbohydrates, in that it raises insulin levels (it also raises glucagon levels). If you really want to mess with your weight in the negative direction, restrict your protein as well to just the bare minimum required to maintain muscle mass.

  7. Alex Curylo says:

    “Your weight probably won’t change that much.”

    I’m suspecting it will, actually. I seem to turn my appetite off and switch over to ketogenesis quite readily whenever I’m active enough to keep my glycogen depleted, like a three pound a week pace, so it seems to stand to reason that suppressing insulin through diet has a good chance of accomplishing the same thing without having to walk several hours a day, which only happens when I’m on a trip somewhere it seems. But check back in a couple months and we should know, looks right now like I should be out of carbs around here within a couple weeks.

  8. Duane Storey says:

    I assumed you were already eating a relatively low carb diet, which would mean switching to a zero carb diet wouldn’t have that much of a greater affect on you.

  9. Alex Curylo says:

    “I assumed you were already eating a relatively low carb diet,”

    No. I avoid anything with added sugars and virtually all fruits (fructose just knocks me right out), but starchy/fibrous carbs have definitely been a majority and probably a high majority of my calories. So going full on carnivore will certainly be an interesting experiment at the very least.

  10. How timely! This is exactly the diet that I’ve been planning on starting after the surgery bruhahah and big move to The Peg have resolved. I’ve read about it in the past, but the 4 Hour Work Week blog dredged it up for me a few weeks ago, and I’ve been thinking about it since.

  11. Luke says:

    I’m interested in the ckd – and i appreciate your remarks about a low to no carb situation over the 4 month period. i am concerned with performance and muscle retention(ala’ army apft), so i look forward to future updates

  12. Tina says:

    Duane, can you please share with everyone your creditionals? What is your background in the field of nutrition? Are you a Registered Dieititian? I think it is important that people know who they are taking advice from. Registered Dietitians have at least 5years of education in the field of nutrition and study this information indept. I am curious to learn your education in regards to nutrition.

  13. Duane Storey says:

    @Tina – I have a readily accessible “About'” section of my website that shows that I’m an engineer. This is my personal site so I think it stands to reason it’s my personal opinion about things. It’s called “Migratory Nerd” after all, and not “Dietician Advice”. There’s also no “advice” per say in this post – I merely give information about a popular diet that already exists.

    That said I have a Master’s Degree in Applied Science which took 8 years of school. I’ve been studying food and nutrition for over a decade since graduating.

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