Can a keto diet benefit patients with diabetes and obesity?

This study looked at how a very-low-calorie ketogenic diet affected people with type 2 diabetes (T2D) and obesity. It found that the ketogenic diet improved weight, blood sugar, and quality of life more than a standard low-calorie diet.

Diabetes involves excessive glucose (sugar) in the blood and can reduce overall health. T2D is closely related to obesity. For patients with T2D and obesity, sustained weight loss can improve blood glucose control. However, weight loss through dieting can be challenging.

A ketogenic diet is based on changing the way the body uses energy. Normally, the body primarily uses blood glucose as a source of energy. The body gets glucose from carbohydrates. A ketogenic diet strictly limits carbohydrates in the diet, such as bread, root vegetables, or beans. When the body does not have access to glucose, it can break down fat into ketones to use as fuel.

A ketogenic diet may improve glucose control. Because this diet includes fat and protein, it can prevent hunger even when calories are reduced. It is not clear whether a ketogenic diet compares to other low-calorie diets for people with T2D and obesity.

This study included 30 patients with T2D and obesity. 15 patients chose a very-low-calorie ketogenic diet (“keto diet”). During the first 45 days, these patients only consumed meal replacement shakes with less than 800 calories per day. After that patients began eating protein- and fat-based foods. After six months, carbohydrates were slowly reintroduced. The other 15 patients chose a standard low-calorie diet of between 500 and 1000 calories daily. The diet emphasized fish, eggs, beans, whole grains, vegetables, and fruit. All of the patients stopped their diabetes medications at the start of the diet program, except for metformin (Glucophage). They were followed for 12 months.

The keto group lost significant weight over the year. At three months, they lost 8.5% of their initial weight. This continued to 11.5% of their initial weight by the end of the year. The standard diet group did not experience clear weight loss. 

After 12 months, the keto group had significantly lower blood pressure. This was true of both the higher pressure as the heart pumps (systolic) and the baseline pressure (diastolic). The standard diet group did not have lower blood pressure after 12 months. The keto group also had better blood glucose control at the end of the year (HbA1c 6.6% to 6.2%). The standard diet group did not have a clear improvement. HbA1c is a measure of blood glucose control over the past 2-3 months.

Surveys were used of overall health and eating patterns. Patients using the keto diet reported less hunger and followed their diet more closely than patients on the standard diet. Patients on the keto diet also ate emotionally less often.

The most common side effects of the keto diet were constipation and dizziness during the first week.

This study found that a very-low-calorie keto diet led to more weight loss, better glucose control, and higher satisfaction than a standard low-calorie diet for patients with T2D and obesity.

Patients chose their own diet. The keto diet may be more suited to some patients than others.

Talk to your doctor before beginning a ketogenic diet or another restrictive diet, as it may affect your diabetes management.