Intermittent fasting is all the rage due to its laundry list of potential health benefits — from weight loss to longevity.
Now, new research suggests that it may beat low-calorie diets when it comes to preventing type 2 diabetes in high-risk people.
Folks who only ate between 8 a.m. and noon for three days a week and ate normally for the other four days showed greater improvements in blood sugar metabolism for at least six months when compared with people who followed a low-calorie diet. Interestingly, folks in both groups lost the same amount of weight during the study period.
“Our study indicates that meal timing and fasting advice extends the health benefits of a restricted calorie diet, independently from weight loss, and this may be influential in clinical practice,” said study author Xiao Tong Teong, a postdoctoral researcher at the University of Adelaide in Australia.
For the study, researchers compared a time-restricted intermittent fasting diet to a low-calorie diet in more than 200 people, to see which had a greater effect on the risk for developing type 2 diabetes. They looked at postprandial blood sugar, a measure of glucose in the bloodstream after eating. If these levels are too high, it suggests a greater risk of type 2 diabetes, the form of the disease most closely related to obesity.
Previous studies suggested eating earlier improves health, but no study has looked at ideal fasting timing, Teong noted. “Our study findings add to the growing body evidence on meal timing with prolonged fasting is key to improve postprandial glucose metabolism in adults at increased risk of developing type 2 diabetes,” she said.
Participants were allowed to change to a weight-maintenance plan after six months or stick with their initial diet. More people in the low-calorie arm stayed on their plan. The blood sugar benefits first seen in the fasting group were lost at 18 months.
Not everyone can or should try intermittent fasting, Teong noted.
“A fasting diet is not recommended for women who are pregnant, people who have eating disorders or diabetes, and people who are on glucose-lowering medications,” Teong said.
People with any underlying health conditions should check with their doctors before trying a fasting diet.
The study was published online April 6 in the journal Nature Medicine.
This is one of the longest and largest intermittent fasting studies to date, said Krista Varady, a professor of nutrition at the University of Illinois at Chicago.
“Blood glucose control was better in the time-restricted eating group versus calorie restriction after six months, but these benefits were no longer seen by the end of the study at month 18,” said Varady, who wasn’t involved with the study.
The time-restricted eating group in the study was only allowed to eat between 8 a.m. and 12 p.m. on fasting days. “This is very hard to sustain long-term as people don’t like skipping dinner with their families/friends on several days per week,” Varady noted.
People stopped following the diet after the first six months in the study. “The long-term feasibility of this eating pattern doesn’t seem great,” she said.
The most popular form of time-restricted eating involves eating between 12 p.m. and 8 p.m. and not counting calories, Varady said. “This intervention is easy to follow since people don’t have to track calories and still allows individuals to engage in social eating every evening,” she explained.
The Academy of Nutrition and Dietetics explains different types of intermittent fasts.
SOURCES: Xiao Tong Teong, PhD student, University of Adelaide, Australia; Krista Varady, PhD, professor, nutrition, University of Illinois at Chicago; Nature Medicine, April 6, 2023
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