The ketogenic, or keto, diet is popular as a way to help people lose weight. But is it a safe, effective method to keep diabetes under control? Scientists are still studying how the diet affects people with the condition, but here’s what we know.
What Is the Keto Diet?
It’s a low-carb, high-fat eating plan. Most of what you eat is fat, whether that’s unsaturated fats like nuts, seeds, and avocados, or saturated fats like butter and coconut oil. About 20%-30% of your diet is protein, either lean (like chicken breast) or fatty (like bacon). You’re supposed to strictly limit carbs, even those that are typically considered healthy, such as beans, whole grains, milk, and many types of fruits and vegetables. On the keto diet, you eat less than 50 grams of carbs a day. To put that in perspective, one medium apple has 25 grams of carbs.
How does it work? Normally, your body fuels itself from sugar, or glucose, that it gets from carbs. After a few days of the keto diet, your body runs out of glucose. So it starts burning body fat instead. This is called nutritional ketosis. It creates fatty acid substances called ketones, which your body can use for energy.
Ketosis vs. Ketoacidosis
If you have diabetes, it’s important to understand the difference between nutritional ketosis and ketoacidosis. Both involve ketones. But ketoacidosis is a dangerous condition that happens when your body doesn’t have enough insulin and ketones build up too much. Symptoms include excessive thirst, urinating often, confusion, and weakness or fatigue. It’s more common for people with type 1 than type 2.
Ketosis happens with much lower, safer levels of ketones than ketoacidosis. In fact, this process happens in the course of everyday life, depending on the amount of carbs and protein you eat. It’s the state that can lead to weight loss, especially belly fat, and lower A1c for many people with diabetes.
Does Keto Work if You Have Diabetes?
Research suggests that people with type 2 diabetes can slim down and lower their blood sugar levels with the keto diet. In one study, people with type 2 lost weight, needed less medication, and lowered their A1c when they followed the keto diet for a year.
If you’re insulin resistant — which means you have higher blood sugar levels because your body isn’t responding properly to the hormone insulin — you could benefit from nutritional ketosis because your body will need and make less insulin.
There are fewer studies looking at the keto diet for people with type 1 diabetes. One small study found that it helped people with type 1 lower their A1c levels, but we need a lot more research to get the full picture of the diet’s effects.
Keep in mind that most studies have only looked at the short-term results of the keto diet. It’s unclear if it works as a long-term way to manage your diabetes.
If you decide to try the keto diet, be aware that it may be hard to stick to. The very low amount of carbs in the plan is a big change for many people. It also can make you feel tired for a few weeks until your body adapts. To make it a success, it’s a good idea to make a meal plan you can follow, including keto-friendly meals and snacks to keep on hand.
Is Keto Safe if You Have Diabetes?
That depends on the type of diabetes you have. In general, people with type 2 who are overweight seem to get good results safely. If you have type 1 and want to try the keto diet, it’s essential that you talk to your doctor first. You’ll need to carefully monitor your health and watch for signs of ketoacidosis. For either type, it’s a good idea to work closely with your doctor, since you may need to change your medications.
The keto diet has some side effects that are worth knowing about, too:
Hypoglycemia: Though the diet can lower A1c levels, that may mean you’re at a higher risk of blood sugar that dips too low, especially if you’re also taking medicine for your diabetes. Let your doctor or diabetes educator know if you try the keto diet. They can advise you about checking your blood sugar, taking your medicines, and what to do when your blood sugar drops too low.
Heart disease: The diet emphasizes eating a lot of fat. If you eat too much saturated fat (the kind in foods like bacon and butter), that could raise your cholesterol, especially LDL, which is linked to heart disease. This is a special concern for people with diabetes, since the condition itself makes you more likely to get heart disease. Make sure that healthier sources are providing your fats — the mono- and polyunsaturated kinds, such as those in foods like avocados, nuts, and olive and canola oils. If you do it right, your LDL cholesterol and triglyceride levels could go down. If you take medicine for heart problems, such as high blood pressure, check with your doctor to see if you need to make changes to your medications.
Lack of nutrients: Since many foods are off-limits, including some fruits, vegetables, and dairy products, you could miss out on the important nutrients you’d get from them. Work with a nutritionist familiar with nutritional ketosis to make sure your body gets what it needs.
Liver and kidney problems: These organs help your body process fat and protein. Some experts worry that the keto diet could overwork them. Others say that if your organs are healthy, you’re probably fine.
Constipation: Since you’re not eating foods like whole grains and beans, you could miss key sources of fiber.
Gallstones: If you lose weight quickly, you could be more likely to get gallstones. Some foods, like those high in fiber and those with healthy fats, could help you prevent them. Talk to your doctor about other ways to avoid gallbladder trouble.
Should You Try It?
Talk to your doctor before you sign up for the keto diet. For some people with diabetes, especially those who need to lose weight, this way of eating can help improve symptoms and lessen the need for medication. But for others, the keto diet could make diabetes worse.
You’ll want to be careful when you transition off of it; adding carbs back in all at once can cause blood sugar spikes and weight gain. Your best bet is to start slowly with carbs that are high in protein and fiber.
WebMD Medical Reference Reviewed by Brunilda Nazario, MD on June 26, 2019
Cleveland Clinic: “What Is the Keto Diet (and Should You Try It)?” “How to Smoothly Transition Off the Keto Diet.”
Harvard Health Letter: “Should You Try The Keto Diet?”
Diabetes Therapy: “Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study,” “Low Carbohydrate Diets and Type 2 Diabetes: What is the Latest Evidence?”
Nutrition & Metabolism: “A low-carbohydrate, ketogenic diet to treat type 2 diabetes.”
Nutrients: “Low-Carb and Ketogenic Diets in Type 1 and Type 2 Diabetes.”
CDC: “Diabetes: What’s Insulin Resistance Got To Do with It?”
Mayo Clinic: “Diabetic ketoacidosis.”
Diabetes Forecast: “What You Need to Know About the Ketogenic Diet.”
National Institutes of Health: “Dieting and Gallstones,” “Eating, Diet, and Nutrition for Gallstones.”
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