Although the adverse effects related to the ketogenic diet are generally less serve than those of anticonvulsant medications used to treat epilepsy, individuals following the diet may experience a number of undesirable effects.
Short-Term Side Effects
There are several short-term side effects that are most evident at the beginning of therapy, particularly when patients commence the diet with an initial fast.
Hypoglycemia is a common side effect in this instance, and noticeable signs may include:
- Excessive thirst
- Frequent urination
- Confusion, anxiety and/or irritability
- Lightheadedness and shakiness
- Sweating and chills
Additionally, patients may also experience some constipation and low-grade acidosis. These effects tend to improve when the diet is continued, as the body adapts to the new diet and adjust the ways in which it sources energy.
Alteration in Blood Composition
As a result of the changes in dietary consumption and the body’s adaptive mechanisms to cope with the reduced carbohydrate intake, there are several changes in the blood composition of individuals following the ketogenic diet.
In particular, the levels of lipids and cholesterol in the blood are commonly higher than what is considered to be normal. More than 60% of patients have raised lipid levels and more than 30% have high levels of cholesterol.
If these changes are profound and there is some concern about the health of the child, slight changes to the diet can be made for the individual patient. For example, saturated fat sources can be substituted for polyunsaturated fats. In some cases, it may be necessary to lower the ketogenic ratio and reduce the proportion of fat to carbohydrate and protein in the diet.
When the ketogenic diet is continued for extended periods of time, there are other adverse effects that become more evident and have a greater impact on individuals.
Kidney stones, also known as nephrolithiasis, are a common complication for children following the diet, with approximately 5% of patients suffering from the condition. It is, however, treatable and the current recommendations suggest that the diet should be continued. The formation of kidney stones is believed to be linked to hypocitraturia and hypercalciuria, when acidosis causes the bone to demineralize. Additionally, low pH in the urine can encourage the formation of crystals and, eventually, kidney stones.
There is some evidence that supplementation with potassium citrate reduces the incidence of kidney stones, as it binds to and reduces the level of calcium in the bloodstream. More research on this is required, however.
Children following the ketogenic diet may be affected by stunted growth, due to reduced levels of insulin-like growth factor 1. This hormone usually plays an important role in the growth of children and is reduced as a result of the diet. For this reason, patients have an increased risk of stunted growth.
Additionally, patients have an increased risk of bone fractures. This arises from the altered levels of insulin-like growth factor 1 and the effects of acidosis. Acidosis leads to the erosion of bone, weakening the bones and leaving them prone to fractures.
In order to manage these side effects, supplementation of vitamins and minerals are routinely administered to patients following the ketogenic diet. This commonly comprises of a multivitamin, calcium and vitamin D supplements.
Side Effects in Adults
For adults following the ketogenic diet, the most common complications include weight loss, constipation and increased levels of cholesterol and triglycerides. Women may also experience amenorrhea or other disruptions to the menstrual cycle.