After much research, it was concluded that a protein intake of 1.5-1.75 grams protein per
kilogram of ideal body weight (ideal body weight was used to approximate lean body mass) would
spare most of the nitrogen loss, especially as ketosis developed and the body’s glucose
requirements decreased. As we shall see below, providing sufficient protein from the first day of a
low-carbohydrate diet should prevent any net nitrogen loss from the body. Of all aspects of the
PSMF or ketogenic diet, adequate dietary protein is absolutely critical to the success of the diet in
maximizing fat loss and sparing body protein.
The ketogenic diet as most consider it is simply a PSMF with added dietary fat. Note that
the addition of dietary fat does not affect the adaptations or protein sparing effects of the PSMF.
Only overall fat loss is affected since dietary fat is used to provide energy instead of bodyfat.
How much dietary protein is necessary to prevent nitrogen losses?
Without going into the details of protein requirements, which are affected by activity and
are discussed in the next chapter, we can determine the minimum amount of protein which is
necessary to prevent body protein losses by looking at two factors: the amount of glucose
required by the brain, and the amount of glucose produced from the ingestion of a given amount of
dietary protein.
Both of these factors are discussed in previous chapters and a few brief calculations will
tell us how much protein is necessary. In the next section, these values are compared to a
number of diet studies to see if they are accurate.
To briefly recap, during the first weeks of ketosis, approximately 75 grams of glucose must
be produced (the other 18 grams of glucose coming from the conversion of glycerol to glucose) to
satisfy the brain’s requirements of ~100 grams of glucose per day. After approximately 3 weeks
of ketosis, the brain’s glucose requirements drop to approximately 40 grams of glucose. Of this,
18 grams are derived from the conversion of glycerol, leaving 25 grams of glucose to be made
from protein.
Since 58% of all dietary protein will appear in the bloodstream as glucose (3), we can
determine how much dietary protein is required by looking at different protein intakes and how
much glucose is produced (table 1).
Table 1: Protein intake and grams of glucose produced *Protein intake (grams) Glucose produced (grams)
50 27
100 58
125 72.5
150 87
175 101.5
200 116* Assuming a 58% conversion rate