Therefore it can not be recommended that the CKD be followed indefinitely and a more ‘balanced’
diet should be undertaken as soon as one’s goals are achieved.
A question which is asked is whether the carb-load is anabolic, stimulating muscle growth
while dieting. As muscle growth requires an overall anabolic metabolism, the body must be
shifted out of ketosis (which is catabolic) during the carb-load. This requires that liver
metabolism be shifted away from ketone production, which necessitates both an increase in
certain enzymes as well as a refilling of liver glycogen. Therefore the carb-load really begins
about 5 hours prior to the final workout when a small amount of carbohydrates should be
consumed to begin upregulating liver enzymes. Approximately 2 hours prior to the workout, a
combination of glucose and fructose should be consumed to refill liver glycogen. Glutamine is an
optional addition that may increase liver glycogen levels.
There are a number of ways that the carb-load might affect muscle growth. The primary
mechanism is by increasing insulin and amino acid availability. The second is by increasing
cellular hydration levels. Both have the potential to increase protein synthesis while decreasing
protein breakdown.
Ultimately the question must be asked as to just how much new muscle can be
synthesized during a carb-up of 24 to 48 hours. Even assuming zero muscle breakdown during
the ketogenic week, the amount of new muscle synthesized is likely to be small. So while
individuals may gain a small amount of muscle during a CKD, it should not be expected or
counted on.
References Cited
- Ivy J. Muscle glycogen synthesis before and after exercise. Sports Medicine (1991) 11: 6-19.
- “Physiology of Sport and Exercise” Jack H. Wilmore and David L. Costill. Human Kinetics
Publishers 1994. - Sherman W. Metabolism of sugars and physical performance. Am J Clin Nutr (1995)
62(suppl): 228S-41S. - Pascoe DD et. al. Glycogen resynthesis in skeletal muscle following resistive exercise. Med Sci
Sports Exerc (1993) 25: 349-354. - Coyle EF. Substrate utilization during exercise in active people. Am J Clin Nutr (1995)
61 (suppl): 968S-979S. - Pascoe DD and Gladden LB. Muscle glycogen resynthesis after short term, high intensity
exercise and resistance exercise. Sports Med (1996) 21: 98-118. - Burke LM et. al. Muscle glycogen storage after prolonged exercise: effects of the glycemic index
of carbohydrate feedings. J Appl Physiol (1993) 75: 1019-1023. - Rankin J. Glycemic Index and Exercise Metabolism. in Gatorade Sports Science Exchange
Volume 10(1). - Costill DL et. al. Muscle glycogen utilization during prolonged exercise on successive days.
J Appl Physiol (1971) 31: 834-838. - Reed MJ et. al. Muscle glycogen storage postexercise: effect of mode of carbohydrate
administration. Med Sci Sports Exerc (1989) 66: 720-726. - Costill DL et. al. The role of dietary carbohydrate in muscle glycogen resynthesis after
running. Am J Clin Nutr (1981) 34: 1831-1836.