Ketogenic Diet: Is It Good for Diabetes and Weight Loss?

With Laura Saslow, PhD, Andrew Reynolds, PhD, J. Michael Gonzalez-Campoy, MD, PhD, and Joseph Galati, MD

Diets that promise successful weight loss get a lot of buzz. So it stands to reason that any diet that promises to reverse your diabetes, promote weight loss, and lower your blood sugar enough so you might get off your meds, is no doubt going to generate even more attention.

That's certainly the case with the ketogenic diet—a very low-carb meal plan—based on the findings of two recently published studies.1,2  Dr. Saslow and her team report that the individuals with type 2 diabetes who followed the keto diet lost significantly more weight than those on the low-fat diet espoused by the American Diabetic Association.These dieters also were able to get their hemoglobin A1c (HbA1c) below 6.5%, suggesting that some may have reversed their type 2 diabetes.1

In a second study,2 a Harvard-led research team evaluated the benefit of a ketogenic diet in both children and adults with type 1 diabetes despite concerns about a possible negative effect on growth and development in children following such a restricted diet. These researchers report "exceptional" glucose control with little adverse effects. However, the participants were recruited from a closed Facebook group, TypeOneGrit, for people who follow a diet and diabetes program based on the recommendations in the Diabetes Solution,a book by Richard K Bernstein, MD, who devised this program to manage his own type 1 diabetes.

Following the Ketogenic diet plus lifestyle improvements can reverse diabetes.The ketogenic diet focuses on lean meat and lots of vegetables to promote weight loss.

Too good to be true? Many experts are pushing back and raising questions about whether the keto diet itself is responsible for the improvement in weight and blood sugar or maybe the dieters' successes are due to other components of the research methods, such as lifestyle differences or physiological changes.

Don't Jump at the Good News Too Quickly

"First, the studies are too small to make sense of the differences between the groups," says Michael J Gonzalez-Campoy, MD, PhD, medical director and CEO of the Minnesota Center for Obesity, Metabolism, and Endocrinology, in Eagan, Minnesota.

And, it's important to recognize that both study teams acknowledge that as exciting as their findings seem, a large, randomized controlled trial is still needed to more closely assess a variety of components that may be contributing to the successes found in both studies before the findings can be recommended to anyone outside the study groups1,2  he says.

"We recommend against 'dieting', which is invariably a short-term solution," Dr. Gonzalez-Campoy, tells EndocrineWeb, "and since weight loss may be accomplished by a reduction in calories by any means, a ketogenic diet that restricts carbs is simply shifting the calories away from foods that typically demand insulin as in both of these studies.1,2  

Instead, the recommendations for diabetes and weight management, he says, are: 

  • control portions
  • emphasize freshness—fresh fruits and vegetables, lean meats, and water—with each meal

As both study groups acknowledge, additional research is needed to tease out any and all of the factors that may be producing the weight loss and decrease in HbA1c, says Dr. Gonzalez-Campoy, for example  there may be other mechanisms of action that are helping these individuals to achieve weight loss, including changes in the gut microbiome, increased insulin sensitivity, enhanced leptin response, and decreased ghrelin levels, each of which contribute to weight loss.

The study deficiencies reinforce the need to avoid encouraging the concept of a "diet" for long-term management of chronic diseases such as diabetes since there are many factors involved in achieving and maintaining a healthy weight and parameters like serum glucose, HbA1c, and blood lipids, Dr. Gonzalez-Campoy says.

What Happened in Type 2 Diabetes Study: Saslow 

"If you follow the ketogenic diet, it's a very efficient way of losing weight and managing your blood glucose and getting off your glucose-lowering medicine," says Dr. Saslow, PhD, the study leader.

The study was a follow-up to earlier research in which she and her team also found that those on the ketogenic diet lowered their HbA1c while those on the conventional low-fat diet did not.4 Just as in the current study, those on the low-carb keto diet also lost more weight.

The more recent study was conducted online to ascertain if this online approach proved effective in eliciting weight loss.1 Dr. Saslow's team randomly assigned the 12 participants to the Keto diet and lifestyle improvement group and another 13 individuals to the traditional low-fat diet known as the Plate Method,1 supported by the American Diabetes Association. 

For the ketogenic eating plan, participants were instructed to reduce non-fiber-containing carbohydrates to between 20 and 50 grams a day, with no calorie restriction. The group following the plate method were told to eat their meals on a nine-inch plate, filling half of it with non-starchy vegetables (eg, greens, peppers, broccoli, carrots), ¼ of the plate with whole grains (eg, brown rice, sweet potatoes, whole wheat bread) and adding lean protein (eg, skinless chicken, turkey, fish, and seafood) to the last quarter of the plate.1

At the start, both groups averaged about 1,700 calories a day, and the average age of the participants was in their mid-50s. Some participants were on metformin to help manage their diabetes, and all had received a diagnosis of type 2 diabetes about five years ago.1

After 32 weeks, those in the keto diet group lowered their HbA1c more than those in the plate group with more than 50% achieving a reduction to less than 6.5%, basically reversing their diabetes. None in the plate group did this well. As for weight loss, those in the keto low-carb group lost on average of 28 pounds, while those in the plate group lost an average of 6.6 pounds.1

The low-carb diet induces ''nutritional ketosis," Dr. Saslow tells EndocrineWeb, which is not the same as ketoacidosis. Ketones are a chemical your body produces when you burn stored fat; if you are on a low-carb diet you may be ''in ketosis.'' Ketoacidosis is different; it is a life-threatening condition in which levels of ketones and blood sugar are dangerously high, which may occur in people who have poorly controlled diabetes.

A Closer Look at the Type 1 Diabetes Study: Lennerz

A total of 316 individuals from the TypeOneGrit community were included in the study since they met the three eligibility criteria: having type 1 diabetes, taking insulin, and following the Bernstein low carb diet for at least three months.2 The clinical data were gathered using an online survey and confirmed with data obtained from medical charts and feedback from the patients' doctors; parents provided data for the participating child. The participants came from the United States, Canada, Australia, and Europe, of which 57i% were female, 42% were children (under 18 years), and 88% were Caucasian. 2

It's important to note that the drop-out rate was substantial and reports of symptomatic hypoglycemia 1-5 episodes) were experienced by 69% of those in the study. The mean carbohydrate intake was 35 grams (+/- 15) daily. Based on self-reported results, the change in HbA1c was -1.45% (+/- 1.04, P < 0.001) with an average HbA1c of 7.2%  associated with greater hypoglycemia; yet, these results are comparable to other study findings. The average blood glucose levels were 104 mg/dL (+/- 16). Final lipid profiles were mixed. The results were similar for adults and children.

Experts Challenge the Authors' Conclusions  

The Keto diet versus Plate Method study triggered some challenges and a bit of criticism. In an editorial, Andrew Reynolds, PhD, a postdoctoral research fellow at the University of Otago, New Zealand, suggests that the much better results in those on the ketogenic diet may be due not to the diet itself but to the lifestyle changes and ongoing support that keto diet group received.5

Those on the ketogenic plan received instructions on how to eat mindfully, the need for exercise and good sleep, and the importance of setting goals. "It could have been a combination of all the support this group received that helped them achieve the greater weight loss," Dr. Reynolds tells EndocrineWeb.

Admittedly, the two groups were also very different, he says, and that also may have affected the results.5 For example, those in the ketogenic diet group weighed, on average, 240 pounds at the start while those in the plate group averaged 198 pounds. Typically in research, the compared groups are more similar than occurred in this study, he says.

Dr. Reynolds reviewed numerous research studies on ketogenic diets,6 and he has found that most studies show that the drop in blood sugar is typically short-term—only lasting during the initial three months or so—but does not last.  "So it is very hard to encourage ketogenic diets when we have no evidence that they work over longer periods of time," he tells EndocrineWeb.

Research is continuing. This was just a pilot study,1 Dr. Saslow says, so we could test the effects in a small group in order to see if working with patients online offered an effective way to have people follow a weight loss program. In her next study, she plans to break down the components of a program to determine which elements are responsible for the weight loss and the decrease in blood glucose and HbA1c.

Contemplating the Keto Diet for Yourself?  

"Those with type 1 diabetes should avoid a ketogenic diet," warns Joseph Galati, MD, a hepatologist at the Liver Specialists of Texas in Houston, "Many patients with type 1 diabetes have some degree of renal impairment, and handling the build-up of ketones and acids in the body may cause too much stress on the kidneys. Of course, any pregnant women with diabetes, especially those requiring insulin should avoid such an extreme diet given the low glucose levels will be a constant [health] threat."

As for individuals with type 2 diabetes, Dr. Galati says, "a very low carbohydrate diet could be tolerated, albeit with extreme caution. Transitioning to a ketogenic diet will require several lifestyle changes as well as careful monitoring of both your food intake and glucose levels and adjustments to your medications. Also, you should increase your water consumption." 

For those who want to follow a ketogenic-type diet, Dr. Reynolds says it is important to first talk to your doctor and to discuss your goals so you can be sure that this approach is suitable for you given your medical and health history. Ongoing monitoring is needed if you do decide to adopt this very carb approach to eating. Seeing your doctor regularly is important to make sure that your blood pressure, lipids, blood sugar, mood, and medications are within normal ranges as you lose weight. Adjustments are likely going to be necessary from time to time.

 

Financial disclosures: There were no conflicts of interest reported except for Dr Bernstein who has received royalties for books on the management of diabetes (which were used by members of the online social media group surveyed in this study). Dr. Hallberg who holds stock options and receives research support from Virta Health, and consulting fees from Atkins. Dr. Rhodes is the site principal investigator in clinical trials for pediatric type 2 diabetes that are sponsored by Merck and AstraZeneca. Dr. Westman has an ownership interest in companies using low-carbohydrate principles, and he receives royalties for books related to low-carbohydrate diets. Dr. Ludwig has received royalties from books on nutrition and obesity; and Dr. Galati is author of Eating Yourself Sick: How to stop obesity, fatty liver, and diabetes from killing you and your family (2018).

 

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