- People who were instructed to practice intermittent fasting for 16 weeks lost more weight and had significantly improved blood sugar control than those given the commonly prescribed diabetes medications metformin and empagliflozin.
- The study focused on a fasting method known as the “5:2 diet,” which involves eating normally for five days a week and then fasting for two days, consuming just 500-600 calories on the fasting days.
- After 16 weeks, the fasting group lost an average of 21 pounds, nearly double the average of 12 pounds lost by people taking metformin. Those prescribed empagliflozin lost an average of about 12.8 pounds over the course of the study.
- Previous research Some studies have looked at whether intermittent fasting is effective for people with type 2 diabetes, but most of the studies have been small and haven’t directly compared fasting with medication.
- The study involved more than 330 overweight or obese adults who had recently been diagnosed with type 2 diabetes.
Courtney PetersonAn expert not involved in the study called the results “exciting.”
“We often think of drugs as more effective than lifestyle changes,” said Peterson, an associate professor of nutritional sciences at the University of Alabama at Birmingham, “but this study shows that lifestyle changes are more effective at lowering blood sugar than drugs. That’s a very compelling argument.”
The 5:2 diet was first introduced 10 years ago as the subject of a BBC documentary and a bestselling book,Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting,” is a book written by British physician Michael Mosley and co-author Mimi Spencer.
The new study on the 5:2 diet was conducted in China, which has the highest number of type 2 diabetes cases in the world, where at least 141 million adults have the disease and half the population is overweight or obese.
The authors of the new study recruited adults with type 2 diabetes and divided them into three groups. In the first two groups, participants were assigned to take either metformin or empagliflozin. In the third group, participants were instructed to follow the 5:2 diet. Women ate only 500 calories on each of two fasting days per week, and men ate no more than 600 calories, about a quarter of their usual calorie intake.
On fasting days, participants consumed small amounts of food: eggs 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 their usual breakfast and lunch and had a light dinner accompanied by a meal replacement drink.
Significant and sustained improvement
In addition to losing weight, the fasting group saw their HbA1c levels, a long-term measure of blood sugar levels, fall by 1.9%, significantly higher than the medication group. About 80% of fasting participants had their HbA1c levels drop below the 6.5% threshold for diabetes, compared with 60% of those taking metformin and 55% of those taking empagliflozin.
The researchers followed up with participants eight weeks after the study ended and found that most people in the fasting group maintained their blood glucose levels below the diabetic threshold, suggesting that the diet “produced significant and sustained improvements in HbA1c levels,” the authors wrote.
The researchers found that the fasting group also experienced greater reductions in waist circumference, blood pressure and triglycerides (a type of fat that circulates in the blood) compared with participants who took medication.
The researchers cautioned that more studies are needed to examine the long-term effects of the 5:2 diet, which includes meal replacements, on people with type 2 diabetes, but said the findings suggest the diet could be a good early lifestyle intervention for people with early-stage diabetes.
Combining fasting with meal replacements
Peterson said the study was large, rigorous and cleverly designed because it essentially combined two dietary interventions that have been proven to be effective for people with diabetes: intermittent fasting and meal replacement diets.
Many studies Diets incorporating low-calorie meal replacement shakes, soups, and bars have been shown to help people lose weight and lower their blood sugar levels. Some research The 5:2 diet has also been shown to help improve blood sugar control.
The downside to the 5:2 diet, Peterson says, is that while you may see impressive results in the first few months, “your results may start to wane” after six months to a year on the diet.
“There certainly appears to be some short-term benefit, but in the long term (over a year or more), it doesn’t appear to be superior to a standard low-calorie diet,” she added.
She also stressed that more long-term studies are needed, but in the meantime, she said, people newly diagnosed with type 2 diabetes might consider talking to their doctor about whether the 5:2 diet, combined with a meal replacement shake such as Optifast, Ensure or Soylent, is worth trying.
He noted that while study participants didn’t experience many adverse events from the fasting regimen, about 6 percent of those who consumed the diet reported symptoms of hypoglycemia, which could be potentially dangerous.
“Anyone who wants to try this should definitely talk to their doctor,” Peterson says, “and not try it on your own.”
Have questions about healthy eating? Email [email protected] Maybe I’ll answer your question in a future column.
