The ketogenic diet is most frequently used as a strategy for weight loss. It can be a useful tool to help some people adhere to a calorie deficit when trying to lose weight. It has been shown to assist with weight loss, decrease body mass index, and decrease waist circumference in people with overweight and obesity in the short term.[1][2][3][4] However, long term studies (more than 6 months) found that the results were similar for people who followed other diets that produced weight loss using a caloric deficit.[5][6][7]
In chronic conditions, the ketogenic diet might be a useful adjunct to regular medical treatments. The ketogenic diet can help to improve glycemic control in people with diabetes.[6][8][2][3] This positive effect on HbA1c, fasting blood glucose levels, and insulin tapers off after about 6 months, similarly to other diets that result in weight loss.[7] For high blood pressure (hypertension), the ketogenic diet has not been shown to be beneficial.[9][2][10] In people with high cholesterol, a ketogenic diet may assist with improving lipid profiles, particularly in increasing the concentration of HDL cholesterol and decreasing triglyceride levels. Caution should be taken in people with very high cholesterol and other risk factors for cardiovascular disease, because a ketogenic diet can increase total cholesterol, LDL cholesterol, and lipoprotein(a) in some people.[9][6][11][8][2][3][7]
The ketogenic diet has also been shown to decrease seizure frequency in people with epilepsy, specifically in childhood epilepsy that does not respond well to standard medical treatments. However, this should always be done in consultation with a doctor and is not a replacement for medical treatments.[12][13][14][15]
Also of interest is the use of the ketogenic diet to prevent, delay, or even treat neurological disorders such as Alzheimer’s disease, Parkinson’s disease, and stroke. At present, not enough evidence exists to recommend the ketogenic diet as a treatment for these complex disorders.[16]
There are other reported benefits of the ketogenic diet (for example, its use in the treatment of depression and anxiety[17] or its use to increase testosterone in hypogonadism[18]) that are not yet supported by robust evidence.