Why the ketogenic diet can help with diabetes and how to tell if it's right for you
- Numerous studies show that the
ketodiet's approach to limiting carbs can help people with type 2 diabetesreduce their medication and lose weight.
- The keto diet reduced blood glucose levels, which helps people with type 2 diabetes control their symptoms.
- Before trying the keto diet, know the risks and side effects including fatigue, vitamin deficiencies, and in certain cases, kidney stones.
- This article was medically reviewed by Samantha Cassetty, MS, RD, nutrition and wellness expert with a private practice based in New York City.
The keto diet is a high-fat, low-carb eating plan. On the keto diet, you're usually eating around 80% fewer carbs than what national guidelines typically advise.
Research shows that the diet's approach to limiting carbs may help people with type 2 diabetes manage their condition. Here's a closer look at how the keto diet works — and what people with type 2 diabetes should know before giving it a try.
Relationship between type 2 diabetes and carbs
Type 2 diabetes means that the body doesn't respond to insulin like it should. The hormone insulin helps your body utilize blood sugar, or glucose, for energy. For patients with insulin resistance or type 2 diabetes, insulin is still produced — but it may be in insufficient amounts or the body doesn't use insulin properly. This causes blood sugar levels to increase. If not treated, chronically high blood sugar levels can lead to heart disease, kidney damage, nerve damage, eye damage, sleep apnea, and more.
To keep diabetes under control, you want to keep your blood sugar levels as close to normal as possible, says Osama Hamdy, MD, an associate professor at Harvard Medical School and senior staff physician at the Joslin Diabetes Center in Boston.
"Glucose in blood comes predominantly from carbohydrates, so eating more carbohydrates increases blood glucose and reducing carbohydrates reduces blood glucose."
That's why the carb-cutting keto diet might be helpful for people with type 2 diabetes.
What the research says
As far as research goes, Hamdy says that there haven't been long-term studies on whether the keto diet can actually prevent type 2 diabetes. But there is some research on the diet's effect on those who already have the condition. Although many of the studies have been done on small groups of participants, the results seem promising.
4 months on keto
For example, in a small study published in Nutrition & Metabolism in 2005, overweight adults (mostly men) with type 2 diabetes followed a keto diet, where they aimed to keep carbs at or below 20 grams per day for four months. At the end of the study, participants were able to reduce or completely stop taking their diabetes medications. Moreover, they also experienced a 16% reduction in their A1c levels, which is the average amount of glucose in the blood in the last 3-months.
"Reduction in A1C indicates improvement in diabetes control, which in turn reduces the chances of diabetes complications on eyes, kidneys, nerves and the cardiovascular system," says Handy
6 months on keto
Another study, published in Nutrition & Metabolism in 2008, looked at how overweight adults with type 2 diabetes fared following a keto diet versus a low-cal-low-glycemic diet for 6 months. (Low-glycemic refers to foods with a low glycemic index that are less likely to spike blood sugar levels.) The study found that while both groups did well, results for the keto group were better in certain areas, including the reduction of A1C levels. Plus: 95% of those on a keto diet were able to cut or lower their medication use, compared to 62% in the low-calorie-low glycemic group.
1 year on keto
A study published in Nutrition & Diabetes in 2017, found that after a year, overweight adults with prediabetes or type 2 diabetes who adhered to a keto diet saw a reduction in their A1C levels and also reduced medication more than those who ate a moderate carb and low-calorie/low-fat diet. Plus, the keto dieters had an average weight loss of 8.3% compared with 3.8% in the low-calorie group. Weight loss can also help keep blood sugar levels in check.
How keto helps with type 2 diabetes
Generally, if you're following the keto diet, you're eating less than 50 grams of carbs per day. Some versions of the diet call for an even smaller amount — around 20 or 30 grams of carbs per day, says Hamdy. For comparison, the Dietary Guidelines for Americans puts the recommended daily carb intake at somewhere between 225 and 325 grams per day.
The Academy of Nutrition and Dietetics describes how the diet works like this: With carbs pretty much out of the picture, the body needs another way to fuel itself. So, it uses fat, which is broken down into ketones — and these ketones become the body's primary energy source. Once that happens, your body enters ketosis. "Ketosis indicates that the body switched its fuel source to stored fat," says Hamdy.
The good news for diabetes? Since blood glucose levels are lower when carb intake is less and ketones don't increase blood glucose levels, diabetes is better kept in control, says Hamdy.
The fact that ketones don't increase blood glucose levels, combined with eating a low-carb diet that also helps keep glucose levels lower, could help explain why research points to the positive effect of the keto diet on type 2 diabetes.
But if you do have type 2 diabetes, your doctor should be monitoring you while you're on the keto diet. That's in part because ketone levels that are too high can be dangerous — changing the degree of blood acidity, and possibly leading to conditions like cardiac arrhythmia, says Hamdy.
Should I try keto if I have type 2 diabetes?
Hamdy says the keto diet isn't harmful for the majority of type 2 diabetes patients. However he also says that "replacing carbohydrates in the diet with any type of fat, like meat or bacon, can result in a significant increase in bad cholesterol." That's why substituting the carbs you're cutting from your diet with healthier proteins and fats, like olive oil, avocados, and nuts, is better than gorging on bacon, steak, and barbecue.
The keto diet also comes with a series of side effects — sometimes referred to as the keto flu — like headache, constipation, and bad breath. Other risks include eventually developing conditions like kidney stones and vitamin deficiencies, according to the Academy of Nutrition and Dietetics. The academy also advises against the diet for people with certain conditions, like eating disorders or those with pancreatic disease, because of the detrimental effect on the pancreas from the high intake of fat.
For his part, Hamdy recommends a modified version of the keto diet for overweight or obese type 2 diabetes patients — one where carb intake is specific to the individual, unhealthy fats — like saturated fat in red meat — is limited, and protein intake, particularly plant-based protein like beans, is higher.
"What most people don't know is that with the keto diet, you are not only losing fat but also losing muscle mass, which is dangerous. The capacity to regain muscle mass again is limited," Hamdy says. "So, replacing carbohydrates with protein instead of fat is a better idea, especially in conjunction with strength training."
In his clinic, Hamdy says that type 2 diabetes patients have had success with weight loss and diabetes control by cutting carbs to 40% of their diet, stick with low-glycemic index carbohydrates, and increased protein.
"For example, Joslin's Why WAIT program, which implements this structured nutrition plan along with exercise and behavioral changes, helped participating patients with diabetes to maintain a 6.9% weight loss for 10 years. They also cut their medications significantly, and many had partial or complete remission from type 2 diabetes," he says.
If you're suffering from prediabetes or type 2 diabetes, the keto diet may be worth considering. Consult with a doctor before trying any type of extreme diet.
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