A new study involving three men concluded that occasional fasting can help reverse type 2 diabetes.

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One researcher says occasional fasting can reverse type 2 diabetes, but other experts aren’t so sure. Getty Images

Three men with type 2 diabetes were able to stop insulin treatment altogether after intermittent fasting, but experts are warning that people shouldn’t try such a practice on their own.

A small study published in BMJ Case Reports looked at three men between the ages of 40 and 67 who tried occasional fasting for approximately 10 months.

All of the men were able to stop insulin treatment within a month after starting the intermittent fasting. One of the men was able to stop insulin treatment after only five days of the fasting technique.

“This study shows that a dietary intervention — therapeutic fasting — has the potential to completely reverse type 2 diabetes, even when somebody has suffered with the disease for 25 years. It changes everything about how we should treat the disease,” Dr. Jason Fung, author of the study and director of the Intensive Dietary Management Program, told Healthline.

Fung’s assertions that type 2 diabetes can be reversed is contrary to the views of other diabetes experts who spoke with Healthline.

“It’s potentially dangerous to tell patients their diabetes has been reversed, because one is always at risk for progression, even if not being treated by medication,” Dr. Matthew Freeby, director of the Gonda Diabetes Center in Los Angeles and the associate director of diabetes clinical programs at the David Geffen UCLA School of Medicine, told Healthline.

Dr. Robert Gabbay, chief medical officer at the Joslin Diabetes Center in Massachusetts, agrees.

“We don’t think of reversing it, but more that it is in remission. Still need to screen for complications as far as we know,” he told Healthline.

More than people in the United States have diabetes and, according to the Centers for Disease Control and Prevention, 90 to 95 percent of them have type 2 diabetes.

In a person with type 2 diabetes, cells don’t respond normally to insulin, which helps control the amount of sugar in the blood.

“When we eat foods containing carbohydrates (breads, cereals, pasta, fruits, starchy vegetables, dairy), the body digests the carbohydrates into single sugars. The pancreas simultaneously receives a signal to release insulin. Insulin is released into the bloodstream and acts as a key to unlock the cells, allowing the single sugars to enter the cells and provide energy,” Lauri Wright, PhD, assistant professor of public health at the University of South Florida, told Healthline.

“Without enough functioning insulin as we see in type 2 diabetes, some of the single sugars build up in the cell and aren’t able to provide cells with energy,” she said.

High blood sugar levels can be damaging to the body and cause other health issues, such as kidney problems, vision loss, and heart disease.

Type 2 diabetes may be managed by healthy eating and exercise. Some people may get prescribed injectable insulin to help manage blood sugar levels.

In Fung’s study, three men attempted intermittent fasting to see the impact it had on their diabetes.

Two of the men fasted every second day for 24 hours. The third man fasted for three days in a week.

On days when the men fasted, they were allowed to drink low-calorie drinks such as water, tea, coffee, and broth. They were also permitted a low-calorie meal at night.

“Fasting is literally the oldest dietary intervention known to mankind, having been used for thousands of years and having been part of human culture and religion for at least as long,” Fung said.

“The thing that surprised me most was how quickly patients got better,” Fung added. “Even after 25 years of diabetes, the maximum time it took to get off insulin was 18 days. All three patients improved their diabetes to the point that they no longer required insulin, and it only took from 5 to 18 days in this study,” he said.

“Imagine taking insulin for 10 years, and all that time, somebody could have treated you with intermittent fasting, and you would not have needed to inject yourself daily for the last decade,” Fung said.

Fung concedes his study is small and more research is needed.

All of the experts who spoke with Healthline urge caution when interpreting the results of such an anecdotal study.

“To many people with diabetes, such a study conclusion can be perceived as insulting,” Raquel Pereira, a registered dietitian specializing in diabetes, told Healthline.

“People with diabetes already suffer from the disease prognosis, complications, and limitations. Imagine hearing that the way that they can manage such disease is to then deprive themselves of nutritious foods, which provide health benefits as well energy and pleasure,” she said.

“As researchers, we must invest our efforts into solutions that are more attainable and have a more positive health impact for the vast majority of people with diabetes,” Pereira added.

She says fasting for a person with diabetes can be potentially dangerous and requires medical supervision.

“The research in fasting is minimal, and we definitely need more well-controlled research trials to determine if there are any benefits, but especially who might benefit,” Pereira said.

“Disordered eating patterns are quite common in diabetes, and I would be very concerned about the long-term consequences of fasting. Many people may feel low energy, low mental concentration, low reflexes, headaches, lower immunity, and as a result have their quality of life and productivity suffer,” she said.

Wright says fasting doesn’t always have a positive effect for people with diabetes.

“For diabetic patients, especially on insulin, fasting can cause hypoglycemia. We see some people that fast or go for long periods of time binge-eat when they resume eating, which is counterproductive for diabetes,” she said.

“A study such as this gives us clues for further research,” Wright added. “The research overall on intermittent fasting in diabetics is limited and needs to be expanded before we can make recommendations supporting fasting.”

A small study of three men with type 2 diabetes showed they were able to stop insulin treatment after intermittent fasting.

However, experts say more research is needed, and people shouldn’t undertake such fasting without consulting with their healthcare provider.