- Over a 16-week period, people who were assigned to practice intermittent fasting lost more weight and improved their blood sugar control to a greater extent than people who were given metformin or empagliflozin, two commonly prescribed diabetes medications.
- The research focused on a form of fasting called the 5:2 diet, in which people eat normally five days a week and then fast for two days, consuming only 500 to 600 calories during their fasting days.
- After 16 weeks, the fasting group lost an average of 21 pounds, almost double the average 12 pounds lost by people taking metformin. Those who were prescribed empagliflozin lost an average of about 12.8 pounds during the study.
- Previous studies have examined whether intermittent fasting could help people with type 2 diabetes, but they were mostly small and did not compare diet with medication.
- The study included more than 330 overweight and obese adults who had recently been diagnosed with type 2 diabetes.
Courtney Peterson, an expert who was not involved in the study, said the results were “exciting.”
“Often we assume that medications are more powerful than lifestyle approaches,” said Peterson, an associate professor of nutritional sciences at the University of Alabama at Birmingham. “But here they showed that a lifestyle approach was more effective at lowering blood sugar than putting people on medication.” This is a very powerful statement.
The 5:2 diet was first popularized ten years ago by a BBC documentary and best-selling book, “The Fast Diet: Lose Weight, Stay Healthy and Live Longer with the Simple Secret intermittent fasting”, by British doctor Michael Mosley. , with co-writer Mimi Spencer.
The new study on the 5:2 diet took place in China, which has more people with type 2 diabetes than any other country in the world. In China, at least 141 million adults have diabetes and half the population is overweight or obese.
The authors of the new study recruited adults with type 2 diabetes and then divided them into three groups. In the first two groups, participants had to take either metformin or empagliflozin. In the third group, participants learned to follow the 5:2 diet. Women consumed only 500 calories on each of their two weekly fasting days, while men consumed no more than 600 calories, or about a quarter of their usual calorie intake.
On their fasting days, participants ate little food: an egg for breakfast, a few servings of fruit or vegetables for lunch, and a light salad for dinner. Each meal was accompanied by a low-calorie meal replacement drink containing healthy fats, protein, vitamins, minerals and other nutrients. On non-fasting days, participants ate normally for breakfast and lunch, then had a light dinner with a drink as a meal replacement.
Significant and lasting improvements
In addition to losing weight, the fasting group saw their HbA1c, a long-term measure of their blood sugar levels, drop by 1.9 percent, significantly more than the groups taking medication. About 80 percent of participants in the fasting group saw their HbA1c levels drop below 6.5 percent, the threshold for diabetes, compared with 60 percent of participants taking metformin and 55 percent of people taking empagliflozin.
Eight weeks after the study ended, researchers followed up with the participants and found that most people in the fasting group kept their blood sugar levels below the diabetes threshold, suggesting that the diet “significantly and sustainably improves HbA1c levels”. the authors wrote.
The researchers found that the fasting group also had greater reductions in their waist circumference, blood pressure and triglycerides, a type of fat that circulates in the blood, compared to participants taking medication.
The researchers cautioned that more studies were needed to examine the long-term effectiveness of the 5:2 meal replacement diet for type 2 diabetes. But they said their findings suggest the diet could be a good initial lifestyle intervention for people with early-stage diabetes.
Fasting combined with meal replacements
Peterson said the study was large, rigorous and intelligently designed because it essentially combined two dietary interventions — intermittent fasting and meal replacements — that have been shown to be effective for people with diabetes.
Many studies have shown that diets that incorporate low-calorie meal replacements, soups, and bars help people lose weight and lower their blood sugar levels. A number of studies have also indicated that the 5:2 diet helps people improve their blood sugar control.
Peterson said one of the downsides of the 5:2 diet is that people often see impressive results in the first few months, but after about six months to a year on the diet, “they start to fall off.”
“It does seem to have a short-term benefit, but in the long term, a year or more, it doesn’t seem to be any better than a standard low-calorie diet,” she added.
She also stressed that longer-term research is needed. But in the meantime, she said people with newly diagnosed type 2 diabetes might consider talking with their doctor about whether it’s worth trying the 5:2 diet in combination with meal replacements like Optifast, Ensure, Soylent or others.
She noted that while study participants didn’t experience many side effects while on the fasting diet, about 6 percent of dieters reported symptoms of hypoglycemia, which can potentially be dangerous.
“People should definitely work with their doctor if they want to try this,” Peterson said. “They shouldn’t try it on their own.”
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