While experts may not agree which diet is best for the treatment of diabetes and obesity, most agree that there’s no one-size-fits-all diet and that the optimal approach often involves a combination of lifestyle modifications, including diet, and medical therapies.
A panel of distinguished clinicians and researchers analyzed four different diets and discussed the benefits of each during the Scientific Sessions symposium Which Diet Is Best for Treatment of Diabetes and Obesity? The presentation can be viewed by registered meeting attendees at ADA2020.org through September 10, 2020. If you haven’t registered for the Virtual 80th Scientific Sessions, register today to access all of the valuable meeting content.
John Wilding, DM, FRCP, opened the virtual symposium with an examination of low-energy/low-calorie diets and why he believes they are a good approach for type 2 diabetes and obesity. Dr. Wilding is Professor of Medicine and Head of Clinical Research in Obesity, Diabetes and Endocrinology at the University of Liverpool, United Kingdom, and President-Elect of the World Obesity Federation.
“Anyone who is trying to lose weight is facing an uphill challenge. It’s a difficult thing to do,” Dr. Wilding said. “So I think we have to remember that we’re trying to beat physiology when we’re supporting someone with obesity and diabetes who is trying to lose weight.”
With that in mind, Dr. Wilding said there’s good evidence from diabetes prevention trials and other studies supporting low-energy diets for weight loss in people with diabetes and obesity. Dr. Wilding noted several advantages of modest energy restriction (a reduction of approximately 500 kcal from usual intake): Most people can easily understand these diets because they use normal food; the diets don’t require spending a lot of extra money on expensive meal replacements; and low-energy diets seem to be as effective as other approaches in the long-term.
“I do think for some people the low-energy diets using meal replacements—the total diet replacement approach—can be useful because it can result in greater initial weight loss, which patients seem to like, and can even result in remission of type 2 diabetes for some,” Dr. Wilding said. “But it’s very important to support the transition back to normal food and toward a healthier diet in the long-term. I think that’s probably the biggest challenge of delivering that approach.”
Jessica Turton, APD, BAppSc (Ex&SpSc), MNutrDiet, a dietitian at the University of Sydney in Australia, followed with a discussion of low-carbohydrate diets and nutritional ketosis.
“Type 1 and type 2 are clearly very different forms of diabetes. However, we’ve known for a long time that diabetes in general is a disease of carbohydrate metabolism. So in any discussion about the dietary management of diabetes, the total amount of carbohydrates has to be important,” Turton said. “And for patients experiencing hypoglycemia, an excess of carbohydrate intake is likely to be their primary nutritional priority.”
Turton noted that low-carbohydrate diets don’t need to be considered as a completely separate option to the other diets discussed during the symposium. Elements from all beneficial approaches can be integrated using medical nutrition therapy, she said.
One of the concerns with low-carbohydrate diets is the potential for micronutrient deficiencies, but Turton said there are proven ways to build low-carbohydrate diets to ensure that patients receive essential nutrients.
“There are studies that show that you can meet the essential micronutrient intakes with low-carb diets, but we definitely need more research on this, and potentially build some kind of model that we can easily use with patients in clinical practice,” she said. “I think it comes down to using low-carb diets in conjunction with medical nutrition therapy so we can really assess patients on an individual basis.”
Miguel A. Martinez-Gonzalez, MD, PhD, Professor and Chair of Preventive Medicine and Public Health at the University of Navarra in Spain, discussed the Mediterranean diet.
“The Mediterranean diet has a long history of use without any evidence of harm,” he said. “The hallmark of the Mediterranean diet is the abundant use of olive oil for all culinary purposes. In fact, in the tradition of the old Mediterranean diets, about 20% or more of calories came from olive oil, so this is an important piece of the Mediterranean diet pyramid.”
Dr. Martinez was the principal investigator of the PREDIMED (Prevención con Dieta Mediterránea) trial at the University of Navarra and coordinator of the PREDIMED Research Network funded by the Spanish Government. PREDIMED was the first randomized primary prevention trial of cardiovascular disease through a dietary intervention based on a dietary pattern approach.
In the trial, 7,447 participants, approximately half of them with type 2 diabetes and the other half with three or more major cardiovascular risk factors, were randomized to three diets: a low-fat diet following guidelines from the American Heart Association, and two active intervention diets relatively rich in fats with participants educated in following the traditional Mediterranean diet.
“This was translated into an important reduction of 30% in the occurrence of cardiac clinical events in both diabetics and non-diabetics,” Dr. Martinez said. “And while weight loss with the Mediterranean diet may not be as great as other diets, studies show that compliance is high and people maintain that weight loss better.”
Thomas Pieber, MD, Professor of Medicine, Chair of the Department of Internal Medicine, and Chair of the Division of Endocrinology and Diabetology at the Medical University of Graz, Austria, discussed intermittent fasting.
“This is kind of a new concept—the timed restriction of food intake, or intermittent fasting,” he said. “There are three major groups of time-restricted feeding, then there’s intermittent fasting, and then there’s also the idea that prolonged fasting could be of value.”
Dr. Pieber said time-restricted feeding is generally defined by limitations in food intake with four to 12 hours between meals. Intermittent fasting usually involves 24 hours or more of no caloric intake, or a very low amount, followed by a 24-hour period of ad libitum eating.
“All of these interventions have shown body weight reduction and improved glycemic control and cardiovascular risk profile,” he said. “However, when it comes to time-driven dietary interventions, unfortunately there is a worrisome paucity of data in humans from adequately designed and powerful [randomized controlled trials] to assess effects of feeding patterns and compare different concepts. Nevertheless, even if we don’t yet know that much about the effects, I think there’s huge potential of intermittent fasting to fight obesity and associated diseases in the future.”
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