Ketogenic Diet

Definition: A dietary pattern that achieves elevated blood ketone levels (generally 0.5 to 3.0 mmol/L). For most adults, this requires a dietary carbohydrate intake of <50 g/day. This is a dietary pattern that is difficult to follow long-term.

Despite the lack of evidence for long-term benefits, and the potential for harmful effects, some patients will choose to follow a ketogenic diet. Be supportive, and assure your patient that you will provide advice and resources to keep them safe while following the diet.

Contraindications:

Following a ketogenic diet is contraindicated in the following circumstances:

Pregnancy
SGLT-2 inhibitor medication: There is the potential for normoglycemic DKA, which could be hard for patients to distinguish from nutritional ketosis.

Benefits:

The ketogenic diet has been used for many years in patients with seizure disorders that are not well-controlled with medications.
Potential aid in weight mamagement
Potentially improved glycemic control

There is little long-term evidence available regarding the benefits of the ketogenic diet in conditions other than for seizure disorders.

Adverse effects (other than the contraindications noted above):

Temporary lethargy and headache (“keto flu”).
Glucagon may not be effective in treating severe hypoglycemia in people who are strictly following a ketogenic diet, due to reduced glucose stores.
Potential failure to distinguish DKA from nutritional ketosis in Type 1 diabetes. Must be used with caution. Advise those with type 1 diabetes and ketones 3 mmol or greater to seek emergency care if they have nausea, vomiting, stomach pain, signs of dehydration or other symptoms of DKA. Those with long standing type 1 diabetes are often not aware that untreated DKA may lead to death.
Pre-pregnancy. Women of child-bearing age should be informed of the potential risks:
- Diets that contain less than about 95 grams of carbohydrate prior to pregnancy may be associated with increased risk of neural tube defects, possibly due to nutritional, particularly folate, deficiencies.
- Diets reduced in carbohydrate and high in protein and fat from animal sources prior to pregnancy may be associated with increased risk of gestational diabetes.
Increased risk of kidney stones, if additional protein and fat come from high-fat animal sources.
Potential nutritional inadequacies.
Potential decrease in bone mineral density.

Bottom line:

Despite the lack of evidence for long-term benefits, and the potential for harmful effects, some patients will choose to follow a ketogenic diet. In that case, consider the following recommendations:

Discourage people on SGLT-2 inhibitors from following a ketogenic diet. If they are insistent, ensure that they're aware of the risks, and educate them about recognizing DKA.
Be supportive, and assure your patient that you will provide advice and resources to keep them safe while following the diet.
Get agreement from the patient that they will treat hypoglycemia with glucose, even though it might mean that ketone levels will decrease.
Consult with a dietitian to ensure nutritional adequacy, and healthy protein and fat choices.
Monitor ketones. Nutritional ketosis often aims for blood ketone levels of 0.5 to 3.0 mmol/L. Most healthcare providers would prefer 0.3 to 0.8 mmol/L. Negotiation might be required with the patient.
Educate the patient with type 1 diabetes in distinguishing DKA from nutritional ketosis.

Contraindications:

Benefits:

Adverse effects (other than the contraindications noted above):

Bottom line:

Further reading: