A low calorie diet can reverse type 2 diabetes and save the lives of millions of sufferers of the preventable condition, research suggests.
Eating between 825 and 850 calories a day for three to five months put the disease into remission in almost half of patients in a new study, according to the Daily Mail.
The Diabetes Remission Clinical Trial (DiRECT), published in the Lancet, looked at almost 300 adults aged 20 to 65 who had been diagnosed with the disease in the past six years.
It showed that participants, who were instructed to slowly reintroduce more food, after one year had lost an average of 10kg, and half had maintained remission without antidiabetic medications.
The researchers argue that their findings show that while bariatric surgery can achieve remission for a large number of diabetics, this "expensive and risky" method is not necessary as diet and exercise alone is "feasible".
Restricting calories or fasting is an increasingly popular method of tackling diabetes. The 5:2 diet, aka The Fast Diet, is the best known of the fasts to reverse the disease and was made famous by Dr Michael Mosley.
Worldwide, the number of people with type 2 diabetes has quadrupled over 35 years, rising from 108 million in 1980 to 422 million in 2014, and is expected to climb to 642 million by 2040.
It affects almost one in 10 adults in the UK, and costs the NHS around £14 billion ($27b) a year.
Addressing the "root cause"
The Newcastle University scientists say that excess calories lead to a fatty liver, which causes the liver to produce too much glucose.
The excess fat is then passed to the pancreas, which causes the insulin-producing cells to fail and thus causing diabetes.
Their previous research suggested losing less than 1g of fat from the pancreas can re-start insulin production, reversing type 2 diabetes.
Co-author Professor Roy Taylor, who has spent almost four decades studying the condition, said current management guidelines focus on addressing the symptoms – by reducing blood sugar levels through drug treatments – instead of "the root cause".
"Diet and lifestyle are touched upon but diabetes remission by cutting calories is rarely discussed," he said.
"A major difference from other studies is that we advised a period of dietary weight loss with no increase in physical activity, but during the long-term follow up increased daily activity is important.
"Bariatric surgery can achieve remission of diabetes in about three-quarters of people, but it is more expensive and risky, and is only available to a small number of patients.
"Our findings suggest that the very large weight losses targeted by bariatric surgery are not essential to reverse the underlying processes which cause type 2 diabetes."
It is "achievable for many people"
The weight management programme began with a low calorie diet, followed by stepped food reintroduction and ongoing support for weight loss maintenance, including cognitive behavioural therapy.
Antidiabetic and blood pressure-lowering drugs were all stopped at the start of the programme.
Almost a quarter of the group achieved weight loss of 15kg or more at 12 months, and nearly half achieved diabetes remission at one year, compared with 4 per cent in the control group.
Critics of low-calorie diets to treat diabetes argue that such a strict regime are unrealistic for many patients, but Taylor disagrees.
"The weight loss goals provided by this programme are achievable for many people," he said.
"The big challenge is long-term avoidance of weight re-gain. Follow-up of DiRECT will continue for four years and reveal whether weight loss and remission is achievable in the long-term."
Co-author Professor Michael Lean, from the University of Glasgow, said: "Our findings suggest that even if you have had type 2 diabetes for six years, putting the disease into remission is feasible.
"In contrast to other approaches, we focus on the need for long-term maintenance of weight loss through diet and exercise and encourage flexibility to optimise individual results."
Diabetics should start the plan early
Another expert, who was not involved in the study, said diabetic patients are best to start a reversal diet when they are first diagnosed and their motivation is high.
Professor Emeritus Matti Uusitupa, from the University of Eastern Finland, said: "Lean and colleagues' results, in addition to those from other studies of type 2 diabetes prevention and some smaller interventions in this setting, indicate that weight loss should be the primary goal in the treatment of type 2 diabetes.
"The DiRECT study indicates that the time of diabetes diagnosis is the best point to start weight reduction and lifestyle changes because motivation of a patient is usually high and can be enhanced by the professional health-care providers.
"However, disease prevention should be maintained as the primary goal that requires both individual-level and population-based strategies, including taxation of unhealthy food items to tackle the epidemic of obesity and type 2 diabetes."
Dr Elizabeth Robertson, director of research at Diabetes UK, said: "These first year findings of DiRECT demonstrate the potential to transform the lives of millions of people. We're very encouraged by these initial results, and the building robust evidence that remission could be achievable for some people.
"The trial is ongoing, so that we can understand the long-term effects of an approach like this. It's very important that anyone living with type 2 diabetes considering losing weight in this way seeks support and advice from a healthcare professional."