Chapter 12:
The Cyclical Ketogenic Diet (CKD)
As with the TKD, the CKD attempts to harness the effects of a ketogenic diet while
maintaining exercise performance. However, rather than providing carbohydrates only around
exercise, the CKD inserts a one- or two-day period of high carbohydrate eating to refill muscle
glycogen. This means that for the CKD to work, muscle glycogen must be depleted fully each
week. A few calculations which appear below show that full depletion of muscle glycogen requires
a fairly large amount of training. This means that the CKD is not appropriate for beginning
exercisers or those who are unable to perform the amount of training necessary.
Although some authors have suggested the use of CKD for mass gains, it is not optimal in
that regard for a variety of reasons which are discussed in chapter 29. This chapter focuses
primarily on optimizing the CKD for fat loss.
The standard format for a CKD is to alternate 5-6 days of ketogenic dieting with 1-2 days
of high carbohydrate eating, although other variations can be developed. Individuals have
experimented with longer cycles (10-12 days) as well as shorter cycles (3-4) days with good
results. A 7 day cycle is more a choice of convenience than anything physiological, since it fits
most people’s work schedule and allows dieters to eat more or less ‘normally’ on the weekends.
The low-carb week of the CKD is identical to the SKD and all of the information discussed
in chapter 9 applies. During the carb-loading phase of the CKD, the body’s metabolism is
temporarily switched out of ketosis, with the goal of refilling muscle glycogen levels to sustain
exercise performance in the next cycle. One question, that unfortunately has no answer, is how
the insertion of a carb-loading phase will affect the adaptations to ketosis, discussed in previous
chapters.
This chapter focuses on the theory behind optimizing both the lowcarb week (in terms of
weight training) as well as the carb-up. Additionally, it has been suggested that the weekend
carb-load may be anabolic for a variety of reasons but this is poorly studied. Possible anabolic
effects of the carb-load are discussed. Finally, specific guidelines for implementing the CKD
appear at the end of this chapter.
Section 1: Muscle glycogen, training, and the CKD
Unlike the TKD, where the goal is to maintain muscle glycogen at an intermediate level,
the goal of the CKD is to deplete muscle glycogen completely between carb-ups.
There are numerous workouts which can accomplish this goal. However, this section will
show calculations based on a Monday, Tuesday, Friday format, for reasons discussed below. The
particular nature of the CKD requires a slightly different workout schedule for optimal results.
For the CKD, the goal of the early week workouts (generally performed on Monday and
Tuesday) is to reduce muscle glycogen from initial levels to approximately 70 mmol/kg, but no