Weight/Fat regain
It is well known that dieting alone shows extremely poor rates of long term success.
Typically less than 5-10% of individuals who lose weight through dieting alone will maintain that
weight loss in the long term. The effects and implications of coming off a ketogenic diet are
discussed in chapter 14. In brief, any fat loss efforts based on caloric restriction alone are
typically bound for failure, regardless of whether the diet used is ketogenic or not.
For some reason, there is a concern that weight regain is more of an issue on ketogenic
diets than other diets. This most likely stems from the confusion between the loss of body weight
and the loss of bodyfat (see chapter 8). The dehydration and glycogen depletion which occurs on
ketogenic diets can be anywhere from 1 to 15 pounds of bodyweight. Thus it is to be expected
that this weight will be regained when carbohydrates are reintroduced into the diet (either
because the diet is being stopped, or for carb-ups as with a CKD).
For individuals who fixate on the scale as the only measure of their progress, this weight
regain can be disheartening and may make the individual fear carbohydrates as the source of
their excess body weight. Dieters must realize that the initial weight gain is water and glycogen
(carbohydrate stored in the muscle) and move past it. Focusing on changes in body composition
(see chapter 8) should avoid psychological problems with the weight regain from replenishing
water and glycogen. Other issues pertaining to returning to a ‘balanced’ diet from a ketogenic (or
cyclical ketogenic diet) are addressed in chapter 14.
Immune system
Anecdotally, there is a great deal of variety in individual response to ketogenic diets in
terms of the immune system. Some individuals have reported a decrease in certain ailments,
notably allergy symptoms, while others become more susceptible to minor sicknesses.
There is limited research into the effects of a ketogenic diet on the immune system with
two studies showing decrements in some indices of immune system status (50,51). However, one
of these studies (50) was done on epileptic children who may consume inadequate protein while
the other was done during a PSMF (51). Therefore, it is difficult to be sure whether it is ketosis, a
lack of protein, or a lack of calories which is causing these decrements in immune system status.
Since no decrease in immune system status was seen when a maintenance calorie ketogenic diet
was given, (26) it would seem that any negative immune systems effects in the other studies
were caused by low calories and inadequate protein.
Optic neuropathy
One unusual side effect of ketogenic diets which has appeared in a few cases is the
development of optic neuropathy, which is a dysfunction of the optic nerve. In all cases, the
problem was linked to the fact that the individuals in question were not receiving calcium or
vitamin supplements for periods of up to a year. Supplementation of adequate B-vitamins,
especially thiamine, corrected all cases which were reported (52,53).