Low-calorie diets found to be best for weight loss with type 2 diabetes

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Researchers have examined all the evidence on diets and weight loss in people with type 2 diabetes. They found that low-calorie meal replacement diets helped people to lose more weight than other types of diets and gave people with type 2 diabetes the best chance of going into remission.

A new review of existing evidence has sought to answer which type of diet is best for losing weight in adults with type 2 diabetes.

Weight loss can have huge benefits for people with diabetes who are carrying extra weight. It can help people reduce their risk of serious diabetes complications like heart disease and stroke, and our landmark DiRECT study showed it helps some people with type 2 diabetes go into remission.

But there aren’t any guidelines for people with type 2 diabetes or their healthcare professionals on the best type of diet for weight loss and remission.

Researchers – led by Professor Mike Lean at the University of Glasgow, who co-leads our DiRECT study – combined data from past studies to give an overall picture of which particular diet is most effective. They also looked to see if any diet gave people a better chance of going into remission.

This type of study is called an umbrella review. It’s considered the best and most informative evidence on a topic because it takes all the available results and combines them. This makes the conclusions far more powerful than the results of a single study.

What’s best for weight loss?

The review revealed that people with type 2 diabetes who went on a very low-calorie diet of around 400-500 calories a day for 8-12 weeks lost the most weight. This type of diet involves swapping your usual meals for a short period with total diet replacement products, often soups and shakes, that are carefully designed to provide the vital nutrients your body needs.

This type of diet on average helped people lose 6.6kg more weight compared to food-based low-calorie diets of around 1000-1500 calories a day. This is because very low-calorie meal replacement diets provide fewer calories.

The evidence also showed that low carbohydrate diets did not lead to greater weight loss than higher carbohydrate, low-fat diets.

High-protein, Mediterranean, vegetarian and low GI diets all led to only a small amount (between 0.3-2 kg) or no weight loss compared to other diets tested, but the researchers found the evidence on these diets was of poor quality.

What’s best for remission?

The researchers found fewer past studies looking at diets to put type 2 diabetes into remission, and none that allowed a direct comparison between different diets.

Their review found strong evidence that DiRECT style low-calorie total meal replacement programmes are effective for around 46-61% of people recently diagnosed with type 2 diabetes on the trials.

There was weaker evidence that Mediterranean diets or diets that replace only two meals a day with formula products can work for some people (between 11-15% went into remission). But there was no compelling evidence for low carbohydrate diets being effective for remission from the research that’s been done so far.

The findings highlight the need for more high-quality clinical trials using a range of dietary approaches, including low carbohydrate diets, for remission.

The researchers flagged that few of the studies they reviewed looked at weight loss or remission past one year. This means we can’t be sure which dietary approaches are best for keeping weight off and staying in remission in the longer term.

No one size fits all

Overall, this research suggests that restricting calories is the most important dietary factor when it comes to weight loss in people with type 2 diabetes.

Short-term very low-calorie meal replacement diets appear to be the most effective at helping people limit their calories and so lose more weight. Weight loss is closely tied with remission. That’s why trials that included a low-calorie meal replacement phase were found to give people the best chance of going into remission.

Dr Lucy Chambers, Head of Research Communications at Diabetes UK, said:

“This review, combining findings from many studies, answers important questions about which diets are most effective for weight loss and remission in people with type 2 diabetes. Diets that focus on reducing calories, such as low-calorie meal replacement diets, rather than reducing intake of certain nutrients or foods groups, such as carbohydrates, were found to give people with type 2 diabetes the best chance of losing weight and going into remission. 

“Weight loss can help people with type 2 diabetes and higher body weights manage their condition and Diabetes UK’s landmark DiRECT study showed that losing a substantial amount of weight – around 15kg – increases the chance of going into remission. But even a small amount of weight loss can have a really positive impact on health and wellbeing.  

“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.”

There are a variety of different ways to reduce your calorie intake. Everyone’s different and what works for some may not for others. It’s also important to remember that low-calorie diets should only be followed for a few weeks or months. In the longer term, having a healthy, balanced diet that includes vegetables, fruit, wholegrains, dairy, seafood, pulses and nuts is vital for overall health.

Low or very low-calorie diets can be challenging. Recently, our DiRECT researchers explored people’s experiences of going on a low-calorie total meal replacement diet as part of the trial. They reported finding the first few weeks of the diet difficult, although generally they found it easier than expected and that rapid weight loss helped to keep them motivated.

However, DiRECT participants also said that coming out of the low-calorie diet phase and reintroducing foods that are part of a healthy, balance diet was tough and they worried about regaining weight.

If you’re thinking of trying a low or very low-calorie diet, it’s important to speak to your GP who can refer you to an NHS dietitian for support to find an approach that works for you. If you live in England your area may have a local low-calorie diet programme which your GP could refer you to.

We also have information on different diet plans for weight loss.