Ketostix (tm) are much deeper when they over consume calories. Obviously at some point a
threshold is reached where fat consumption is higher than utilization, and fat will be stored.
One study has examined the effect of increasing amounts of dietary fat while on a low-
carbohydrate diet and found that up to 600 grams of fat per day could be consumed before weight
gain began to occur (48). This effect only occurred in subjects given corn oil, which is high in
essential fatty acids, but did not occur in subjects given olive oil, which is not. The corn oil
subjects reported a feeling of warmth, suggesting increased caloric expenditure which generated
heat. This obviously deserves further research.
The ketogenic diet at very low calorie levels (VLCD, below 1200 cal/day)
As with the studies on protein sparing, VLCD studies comparing ketogenic to non-
ketogenic diets tend to be highly variable in terms of results. Some studies show greater
weight/fat and less protein losses (19,24,46,49) while others show the opposite
(10,15,21,23,25,26,50). The variability is probably related to factors discussed previously: short
study periods, insufficient protein in many studies, and exceedingly low calorie levels.
Additionally, few studies incorporate exercise, which has been shown to improve fat loss
while sparing muscle loss. Therefore, it is difficult to extrapolate from these studies to the types
of ketogenic diets discussed in this book (with a moderate caloric deficit, sufficient protein, and
exercise). Ultimately these studies should should not be used as evidence for or against ketogenic
diets.
The ketogenic diet at low calorie levels (10% below maintenance to 1200 cal/day)
In contrast to the results seen with ketogenic VLCDs, there is slightly more evidence that
a ketogenic diet will show greater fat loss and less muscle loss than a non-ketogenic diet at higher
calorie levels. However, more research is needed at moderate caloric deficits. Since there are few
studies done comparing fat loss/muscle loss at this caloric level, they are discussed in more detail.
In one of the earliest studies of low-carbohydrate diets, subjects were fed 1800 calories,
115 grams of protein, and varied carbohydrate from 104 grams to 60 grams to 30 grams (18).
Fat was varied in proportion to carbohydrate to keep calories constant. The diet was fed for 9
weeks. Total fat loss was directly related to carbohydrate content with the highest fat loss
occurring with the lowest carbohydrate content and vice versa. Since there were so few subjects
in each group, the data for each subject is presented. The data from this study appears in table
2 on the next page.
By examining the data for each subject, some patterns emerge. First and foremost, there
is a definite trend for greater fat loss and less LBM loss as carbohydrates are decreased in the
diet. However, there is a large degree of variability (note that subject 3 in the medium
carbohydrate group lost less muscle than subject 3 in the low carbohydrate group). Before
drawing any ultimate conclusions from this study, it should be noted that the protein intake is
still below what is recommended in this book, which might change the results in all diet groups.
Additionally, the low carbohydrate nature of all three diets, relative to current dietary