If you have diabetes you know that carbohydrates are important. So it may seem like an ultra low-carb diet, the ketogenic diet, is the solution to managing your diabetes with food. But is keto all its cracked up to be? Plus, is it safe to "go keto" if you have diabetes? We take a look at the latest research around keto and diabetes and what the ketogenic diet does to your blood sugar.
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Despite its recent rise in popularity for weight loss, diabetes and more, the ketogenic diet was developed as a medical nutrition therapy intervention for epilepsy in the 1920s. Though it may seem like a fad diet, this approach has true clinical application in the appropriate settings (See our Ketogenic Diet 101: A Beginner's Guide to learn more).
The ketogenic diet is a high-fat, moderate-protein, low-carbohydrate diet. Usually 5 percent or less of energy intake is from carbohydrates. In contrast, the Dietary Guidelines recommend that 45-65 percent of daily calories come from carbohydrates.
The body prefers to use carbohydrates, broken down to glucose, as its main energy source. When your carb intake is extremely low and glucose is not available for energy, the body enters a metabolic state called ketosis where it breaks down fat for energy instead. In this state, the body uses ketone bodies for energy instead of glucose until you start eating carbohydrates again.
Because the keto diet limits carbs, it makes sense that it would lower blood sugar. And numerous studies confirm that it does.
A 2017 study compared two online interventions for overweight adults with type 2 diabetes where one group followed a low-carbohydrate ketogenic diet and the other followed a program based on the American Diabetes Association's "Create Your Plate" diet. After 32 weeks, or about 7 months, the keto group lost more weight and had lower A1C and triglyceride levels. While this is compelling, no long-term follow-up was conducted so it's unclear if participants kept up with this diet and maintained the results over time.
Another study compared a low-carbohydrate diet (less than 20 grams/day from carbs) to a low-glycemic, reduced-calorie diet (500-calorie per day deficit) in obese adults with type 2 diabetes. Both groups had improved blood glucose control and weight loss, but the low-carb group saw better blood sugar control. The keto diet often leads to weight loss, which alone can improve blood sugar control, but this study found that the low-carb group had improved blood sugar control independent of weight loss. So it could be beneficial to reduce daily carb intake below the standard recommendation of 45-50 percent of calories from carbs, the researchers said.
The ketogenic diet improves blood sugar control in the short term, but the question is whether you can follow it long-term. "This is a restrictive meal plan and not for everyone," says Erin Palinski-Wade, RD, CDE, author of 2-Day Diabetes Diet. "When it comes to managing diabetes, you need to focus on lifestyle changes you can stick with long-term. If you cannot envision yourself following a keto diet long-term then it may not be the best choice for diabetes management for you."
Plus, research shows that healthy lifestyle changes with moderate carbohydrate intake can also improve blood sugar control. And they might be easier to keep up with long-term. The Mayo Clinic, the American Diabetes Association and the National Institute of Diabetes and Digestive and Kidney Diseases all recommend lifestyle changes such as following the Healthy Plate method to increase fiber, limit simple sugars and eat healthy protein and fat; losing weight; and exercising.
Molly Cleary, M.S., RD, CDE, a registered dietitian and certified diabetes educator based in New York City, says, "If executed properly and under the supervision of a Registered Dietitian, the keto diet could be appropriate for people with diabetes; however, less-restrictive and better-researched diets such as the Mediterranean diet or the DASH diet are better options."
"When you remove carbs from the diet, blood sugar levels drop," says Palinski-Wade. This is why keto can help improve blood sugar management and insulin sensitivity. "However, people shouldn't choose foods solely based on their effect on blood sugar," says Cleary. "Other factors such as fiber, vitamins, minerals, antioxidants and satisfaction must be taken into account. The keto diet would likely lead to better blood glucose control short-term; however, this would only lead to improvements in health status if the diet is followed long-term."
Learn more: 12 Healthy Ways to Lower Your Blood Sugar
People with both type 1 and type 2 diabetes can follow the keto diet, but you should do so under the supervision of your medical team and a registered dietitian. Oral diabetes medications and insulin lower your blood sugar. If you restrict carbs to 5 percent or less of daily calories on top of medications, your blood sugar could drop too low, leading to hypoglycemia.
Also, the ketogenic diet is only effective if you maintain a state of ketosis. This is difficult for many people due to lifestyle factors such as exercise, traveling for work or leisure, or eating out often. Following the diet correctly requires time and dedication to meal prepping and understanding how many carbs, protein and fat are in various foods. There are also some sneaky side effects to keto.
The keto diet is not a good option if you have a history of disordered eating or have experienced bingeing with restrictive diets. In these cases, a moderate approach such as following the Healthy Plate method is better.
Research shows that the keto diet can help blood sugar control in the short term, but long-term research is lacking. You'll only keep seeing results if you can keep up with the diet long-term. If you decide to give it a try, do so under the supervision of your medical team. But, you don't have to go keto to manage diabetes. You can also improve blood sugar control through lifestyle changes you can maintain over time, like increasing fiber, reducing refined grains, choosing healthy fats and exercising.