Other macro-nutrients
Another issue regarding the carb-load is the amounts and types of other macronutrients
(protein and fat) which should be consumed. The ingestion of protein and fat with carbohydrates
do not affect the levels of glycogen storage during the carb-up as long as carbohydrate intake is
sufficient (18). Some dieters find that too much dietary fat blunts their hunger and prevents
them from consuming enough carbohydrates to refill glycogen stores.
Recall that carbohydrate level is 10 gram/kg LBM during the first 24 hours. This will
make up 70% of the total calories consumed during the carb load. Protein and fat will make up
15% each.
Many bodybuilders may feel that this percentage of protein is too low but this is not the
case. First and foremost, a high calorie intake reduces protein requirements and increases
nitrogen retention (19). As a result, less dietary protein is needed when calorie/carbohydrate
intake is high. Protein should be consumed with carbohydrates as this has been shown to
increase glycogen resynthesis, especially after training (20)
Further the most protein lifters need is 1 gram per pound of bodyweight under extremely
intensive training conditions (21). Even at 15% protein calories, most individuals will be
consuming sufficient protein during the carb-up. Specific calculations for the carb-load phase
appear in section 5.
Fat gain during the carb-up
During the first 24 hours of the carb-load, caloric intake will be approximately twice
maintenance levels. This raises concerns regarding the potential for fat gain during this time
period. We will see that fat gain during the carb-up should be minimal as long as a few guidelines
are followed.
In a study which looked surprisingly like a CKD, subjects consumed a low-carb, high fat
(but non-ketogenic) diet for 5 days and depleted muscle glycogen with exercise (22). Subjects
were then given a total 500 grams of carbohydrate in three divided meals. During the first 24
hours, despite the high calorie (and carb) intake, there was a negative fat balance of 88 grams.
This suggests that when muscle glycogen is depleted, incoming carbohydrates are used
preferentially to refill glycogen stores, and fat continues to be used for energy production.
Additionally, the excess carbohydrates which were not stored as glycogen were used for
energy (22). In general, the synthesis of fat from glycogen (referred to as de novo lipogenesis) in
the short term is fairly small (23,24). During carbohydrate overfeeding, there is a decrease in fat
use for energy. Most fat gain occurring during high carbohydrate overfeeding is from storage of
excessive fat intake (25). Therefore, as long as fat intake is kept relatively low (below 88 grams)
during the carb-up phase of the CKD, there should be minimal fat regain.
In a similar study, individuals consumed a low-carb, high fat diet for 5 days and then
consumed very large amounts of carbohydrates (700 to 900 grams per day) over a five day
period. During the first 24 hours, with a carbohydrate intake of 700 grams and a fat intake of 60
grams per day, there was a fat gain of only 7 grams. Collectively, these two studies suggest that
the body continues to use bodyfat for fuel during the first 24 hours of carb-loading.