- Scientists have been studying the effect of diet on type 2 diabetes for years. Research has shown that losing weight can lead to remission.
- However, previous studies have yielded conflicting results, and it is unclear which diets are most effective.
- A recent review of previously published data found that very low energy diets and meal replacement were the most effective way to manage weight in people living with type 2 diabetes.
The International Diabetes Federation (IDF) reports that 1 in 10 adults are living with diabetes. Type 2 diabetes accounts for more than 90% of these cases.
The IDF estimates that diabetes will affect 643 million people worldwide by 2030, with the number rising to 784 million by 2045.
A number of studies have investigated the impact of weight loss on type 2 diabetes. However,weight loss can vary widely between diets, and comparisons have produced conflicting results. There is still uncertainty over which type of diet medical professionals should recommend.
A global team of researchers led by Prof. Michael Lean of the University of Glasgow in the United Kingdom set out to examine the previous research.
Their aim was to find the most effective dietary approach for losing weight, maintaining weight loss, and achieving remission from type 2 diabetes. The research is part of a program of work to update the recommendations of the European Association for the Study of Diabetes.
The researchers found that very low energy diets and meal replacements were the most effective way for people with type 2 diabetes to manage their weight. The review results appear in the journal Diabetologia.
Dr. Lucy Chambers, head of Research Communications at Diabetes UK, told Medical News Today, “This review, which combines findings from many studies, answers important questions about which diets are most effective for weight loss and remission in people with type 2 diabetes.”
Reviewing the published research
Experts widely accept that weight loss benefits treatment of type 2 diabetes. The landmark Diabetes Remission Clinical Trial (DiRECT), led by Prof. Lean, showed that it is possible to achieve remission from type 2 diabetes by maintaining over 10 kilograms (kg), or 22 pounds (lb), of weight loss.
Building on this research, Prof. Lean collaborated with Dr. Chaitong Churuangsuk and colleagues from the University of Glasgow and other researchers from the University of Cambridge, U.K., and the University of Otago in New Zealand.
The team performed an “umbrella review” of previously published data from studies across the globe. They collated meta-analyses that investigated which type of diet is best for achieving weight loss in adults with type 2 diabetes. They also conducted a new systematic review of published studies of diets for type 2 diabetes remission.
What did they find?
The results of the analysis show that weight management programs that included very low energy diets and formula meal replacements provided greater weight losses than conventional low energy diets.
Programs that included a total diet replacement at the start of the diet were the most effective approach for type 2 diabetes remission, reporting for a median 54% of the participants at a 1-year mark.
Moreover, diets such as high protein, Mediterranean, vegetarian, and low glycemic diets achieved little — 0.3–2 kg (0.7–4.4 lb) — or no difference in weight loss, compared with conventional diets.
“It was a bit of a shock, given all the hype and media attention, to discover how poor the evidence is for the low carb, or ketogenic, diets,” Prof. Lean told MNT. “This marketing of low carb diets often uses very persuasive but incorrect science, suggesting that only one nutrient (carbohydrate) and one hormone (insulin) control our metabolism and disease risks.”
“Celebrities and politicians have been persuaded, but dozens of clinical trials have been done, and they simply do not show any advantage for low carb diets. What matters is keeping your weight as near to ideal as possible.”
– Prof. Michael Lean
Limitations
One limitation of the current review is that most of the available evidence relates only to short-term outcomes. The benefits of weight loss on type 2 diabetes depend mostly on long-term control of body weight.
Also, keeping weight lower may require different behavioral approaches than those that work well for the initial weight loss phase. There are few trials that report data beyond 12 months.
Further work
According to the research team, well-conducted research is necessary to assess longer-term impacts on weight, glycemic control, clinical outcomes, and diabetes complications.
Prof. Lean told MNT that “the big need is to find better ways to help people avoid returning to the eating patterns [that] caused them to gain weight and develop [type 2 diabetes]. We know from DiRECT that people who lose weight and get a remission of their diabetes will relapse if they regain weight.”
“This is not easy, because social marketing by the food industry over the last 40 or 50 years has ‘normalized’ eating habits that have resulted in people being on average about 1 stone — 7kg — heavier now, and many of them much heavier at younger ages.”
Dr. Chambers added: “It’s important to remember that there’s no one-size-fits-all ‘diet for diabetes.’ Low calorie diets can be challenging, and if you have [type 2 diabetes] and want to lose weight, getting support from a healthcare professional can help you find an approach that is safe and works for you.”
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