Has anyone heard of this? This is all I could find...
Although ketogenic diets are useful for fat loss, while simultaneously sparing muscle loss, they have one significant drawback: they cannot sustain high intensity exercise. Activities like weight training can only use carbohydrates as an energy source, ketones and free fatty acids (FFA) cannot be used. Therefore the lack of carbohydrates on a ketogenic diet will eventually lead to decreased performance in the weight room, which may result in muscle loss, and carbohydrates must be introduced into a ketogenic diet without affecting ketosis. Probably the most common way to do this is to do a weekend carb-load phase, where ketosis is abolished. During this time period, assuming training volume was sufficient to deplete muscle glycogen (see last article), the body can rapidly increase muscle glycogen levels to normal or supra-normal levels prior to beginning the next ketogenic cycle.

a Cyclic Ketogenic Diet is a ketogenic low-carbohydrate diet. In other words, this is not a diet you do day in, day out for X number of weeks, months or years: it is a diet that you break frequently. In fact, it is the only diet that you are supposed to break, and break often.

The CKD is used to avoid ketosis. When following a Low-Carb diet, for the first few weeks, there is an adaptation period during which most people report feeling run-down or tired. The slightest exertion causes muscles to burn. People feel irritable, out of sorts, and unable to make decisions. For most people these feelings disappear after the adaptation period, however, and are replaced with feelings of calm and balance, consistent energy. Not everyone is dedicated enough to wait long enough for the body to adjust, so the potential for burnout on a non-cyclic ketogenic diet (like Atkins) can be high. People crave carbohydrates during ketosis, for physiological reasons. During a hypocaloric ketogenic diet, this temptation becomes even stronger, as the carb cravings are combined with the usual hunger pangs that accompany reduced calories.

A CKD offers a way to combat this. It offers a cyclical "refeed" (sometimes also called a carb-up). What happens during a refeed is that the dieting individual will change their diet to comprise mostly complex carbohydrates, limiting dietary fats as well as sucrose and fructose. Since the glycogen stores in their liver and muscles are depleted, these carbohydrates go straight to refilling them, instead of being added to the body's fat stores. For this reason, the amount of calories consumed during a refeed can be far above an individual's maintenance intake.

The goals of a refeed are threefold:

a) to refill depleted glycogen stores

b) to upregulate hormones and thyroid activity that is depressed during dieting

c) to provide a psychological "break" that makes the rest of the diet easier to bear

A refeed is risky, as a careless individual can end up gaining fat, instead of losing it, If he/she eats more carbs than is needed to refill their glycogen stores. The timing, duration and macronutrient composition of a refeed are crucial to the diet's overall success.

You should note, because I know that the ketogenic diet is sometimes done with people who have diseases such as parkinsons, that making your ketogenic diet cyclic if you have a condition it could be dangerous with, well it should not be done.

Or perhaps putting it another way...A VLCD non-ketogenic diet may have the same fat loss as a VLCD ketogenic diet....its the protein level thats more important to spare LBM? As far as what is lost, the level of protein is more important, rather than whether you are in ketosis or not??

Ack...I dunno.