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Chapter 6:

Changes in body composition

Having discussed the primary metabolic adaptations which occur during ketosis in the
previous chapter, we can now examine the effects of ketogenic diets on body composition. The
first issue to examine is the effect of food intake on ketosis. This will lead into an examination of
protein sparing on a ketogenic diet, as well as issues involving weight, water, and fat loss.

The question to be answered is whether a ketogenic diet does in fact cause greater fat loss
with less loss of body protein than a more ‘balanced’ diet. Unfortunately, the lack of appropriate
studies, as well as a high degree of variability in study subjects, make this a difficult question to
answer unequivocally. Issues relating to water loss on a ketogenic diet are discussed as well.

Section 1: Macronutrients and Ketosis

Before discussing how to prevent nitrogen loss during starvation, we need to briefly discuss
the effects of different nutrients on the development of ketosis. Both protein and carbohydrate
intake will impact the development of ketosis, affecting both the adaptations seen as well as how
much of a ‘protein sparing’ effect will occur.

Despite the generally ‘high fat’ nature of the ketogenic diet, or at least how it is perceived,
dietary fat intake has a rather minimal effect on ketosis per se. Fat intake will primarily affect
how much bodyfat is used for fuel. Although alcohol has been discussed within the context of
ketoacidosis, the effects of alcohol intake on the state of ketosis are discussed again here.

The ketogenic ratio

Although its application for ketogenic dieters is somewhat limited, the simplest way to
examine the effects of food consumption on ketosis is to look at the equation used to develop
ketogenic diets for childhood epilepsy (figure 1).

Figure 1: The ketogenic ratio

Ketogenic K 0.9 fat + 0.46 protein

------------------- = ---- = -------------------------------------------------

Anti-ketogenic AK 1.0 carbohydrate + 0.1 fat + 0.58 protein

Note: Protein, fat and carbohydrates are in grams.

Source: Withrow CD. The ketogenic diet: mechanism of anticonvulsant action. Adv Neurol
(1980) 7: 635-642.