Like any dietary approach, the ketogenic diet is not universally applicable. Individuals
with certain preexisting medical conditions should seriously consider whether an extreme approach such as the ketogenic diet is appropriate. Although little data is available on this topic, some major conditions which might preclude the use of a ketogenic diet are discussed below.
Although no data exists to suggest that the ‘high protein’ nature of a ketogenic diet is
problematic for individuals with normal kidney functioning, high protein intake may cause problems for individuals with preexisting conditions. Therefore, individuals who are prone to kidney stones should seriously consider whether the ketogenic diet is appropriate for them. The slight dehydration which occurs coupled with a high protein intake may increase the risk of stones. For individuals on the ketogenic diet, it is imperative to drink sufficient water and to be aware of the potential for problems.
As previously discussed, Type I (insulin-dependent) diabetics may have problems with
ketoacidosis if insulin levels drop too low. Since these individuals rely on injections to normalize insulin, a ketogenic diet conceivably poses no problems. However, the lack of carbohydrates, as well as changes in insulin sensitivity, on a ketogenic diet will affect insulin requirements.
Any Type I diabetic who wishes to try a lowered carbohydrate diet must consult with their physician or health provider to determine changes in their insulin regimen.
Type II (non-insulin dependent) diabetics are frequently drawn to low carbohydrate or ketogenic diets as they may help to control blood glucose and insulin levels. Individuals with severe hyperinsulinemia and/or hypoglycemia will need to be careful. When implementing a ketogenic diet to avoid problems with blood sugar crashes and related difficulties.
Individuals with Type II diabetes may have greater difficulty establishing ketosis. As some data suggest that liver glycogen is more difficult to deplete. Additionally, it has been found that obese individuals, who typically suffer from insulin resistance, have greater difficulty establishing ketosis. This points even more to the importance of exercise to help deplete liver glycogen and establish ketosis.
Coronary artery disease/high cholesterol
For many individuals, the ketogenic diet causes an improvement in blood lipid levels, especially in cases where body fat is lost. However, this is not a universal finding. Individuals with diagnosed coronary artery disease or high blood cholesterol must monitor their blood lipid levels for negative changes. Individuals who show negative changes can try decreasing saturated fat intake while increasing unsaturated fat. Additionally, a fiber supplement may be helpful. If blood cholesterol
levels continue to respond negatively, the ketogenic diet should be abandoned.
Individuals with a past history or genetic propensity for gout should seriously consider
whether or not a ketogenic diet is appropriate. As discussed previously, a rise in uric acid levels occurs when the ketogenic diet is started and this may trigger gout in predisposed individuals. Since even small amounts of dietary carbohydrates (5% of total calories) appear to alleviate problems with uric acid buildup, a less restrictive ketogenic diet may be possible for individuals who are prone to gout.
Read more: How To Avoid Common Ketogenic Diet Mistakes
This author is unaware of any research looking specifically at the effects of the ketogenic diet in pregnant humans. However, malformations of the neural tube occur with increased frequency in diabetic mothers and exposure of pregnant female rats to high ketone levels can increase the risk of these same neural tube defects, suggesting that ketones may be a cause. Additionally, it appears that glucose is the primary fuel for the developing fetus.
Considering the above data, as well as the potential harm which might occur to an unborn child, a ketogenic diet is not considered appropriate during pregnancy. In fact, any diet whose aim is weight or fat loss is inappropriate during pregnancy as diet should be optimal to support the developing fetus and the mother.
Although the ketogenic diet has shown a great impact on the treatment of childhood epilepsy, the diet used for epilepsy is significantly different than the diet described in this book. Additionally, implementation of the ketogenic diet for therapeutic purposes requires medical supervision. Under no circumstances should individuals attempt to implement the ketogenic diet for the treatment of epilepsy without medical supervision.
Although the epileptic diet is used in children under the age of 10, its use in adolescents is less well studied. From the standpoint of fat loss, the pediatric epilepsy diet is used for weight loss if necessary, by adjusting calories (8). Additionally, the protein sparing modified fast has shown some benefits in treating morbid childhood obesity (9). Although adolescent obesity is increasing, parents should be careful in self-administering diets, due to the possibility of stunted or altered
growth. Due to the lack of data on the CKD, and due to the hormonal fluctuations which occur, its use is not recommended in adolescents.
There are certain medical conditions which either directly preclude the use of the ketogenic diet. Or that warrant serious consideration prior to beginning such a diet. While there is no data for a majority of disease states, individuals should exercise caution prior to making any large scale changes in diet. When in doubt, the proper medical authorities should be consulted and no self-diagnosis should be made.
Source: The Ketogenic Diet-A complete guide for the Dieter and Practioner by Lyle McDonald