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Researchers say intermittent fasting can help people with type 2 diabetes control their blood sugar levels. The Good Brigade/Getty Images
  • Researchers report that intermittent fasting is as effective for losing weight as diets that reduce calorie intake by 25%.
  • They say the difference was people using intermittent fasting for type 2 diabetes found it easier to lose weight than those told to reduce calories without time restriction dieting.
  • No adverse health effects of either method of lowering blood sugar were detected in either study group.

Intermittent fasting, also known as time-restricted eating, can help people with type 2 diabetes lose weight and control their blood sugar levels, according to researchers from the University of Illinois Chicago.

Their study was published today in the journal JAMA Network Open.

In it, researchers say participants who ate only between noon and 8 p.m. each day without calorie counting lost more weight over 6 months than participants instructed to reduce their calorie intake by 25%.

Both groups saw reductions in long-term blood sugar levels, as measured by a hemoglobin A1C test, which shows blood sugar levels over the previous 3 months.

The researchers put 75 participants into three groups: those following the time-restricted eating rules, those reducing calories, and a control group.

Over the course of 6 months, researchers measured participants’ weight, waist circumference, blood sugar levels, and other health indicators.

Krista Varady, PhD, a senior study author and a professor of kinesiology and nutrition at the University of Illinois Chicago, said in a statement that participants in the time-restricted group found it easier to follow the regimen than people in the calorie-reducing group.

Researchers said they believe this is partly because doctors usually tell people with type 2 diabetes to cut back on calories as a first line of condition management. The team said many of these participants likely already tried and struggled with that form of dieting.

Participants in the time-restricted group weren’t instructed to reduce their calories but did so anyway by eating within a fixed window.

“Our study shows that time-restricted eating might be an effective alternative to traditional dieting for people who can’t do the traditional diet or are burned out on it,” said Varady. “For many people trying to lose weight, counting time is easier than counting calories.”

Researchers said no one reported serious adverse health events during the 6-month study. Occurrences of hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar) didn’t differ between the groups.

The researchers said it is crucial to find more options to control weight and blood sugar levels as one in 10 people in the United States has diabetes and one in three have prediabetes.

Slightly more than half the study participants were Black and 40% were Hispanic, which is notable as diabetes is particularly prevalent among those groups, the researchers said.

Varady said the study was small and should be followed up by larger ones. While it likely shows time-restricted eating is safe for people with type 2 diabetes, Varady said people with the condition should consult their doctors before starting this sort of program.

Dr. Kevin Huffman, a bariatric physician as well as the chief executive officer and founder of Ambari Nutrition who was not involved in the study, told Medical News Today he’s seen firsthand that intermittent fasting can be a powerful tool to fight diabetes when done under medical supervision.

“During these fasting periods, insulin le­vels decrease­, allowing cells to become more­ receptive to insulin whe­n eating resumes,” Huffman said. “This incre­ased sensitivity helps re­gulate blood sugar levels more­ effectively, re­ducing the risk of dangerous spikes and crashe­s that are common in diabetes.”

“Intermittent fasting can also promote­ weight loss — an essential factor in managing type­ 2 diabetes — as shedding e­xcess weight often le­ads to enhanced insulin sensitivity and be­tter overall glycemic control,” he added. “As a re­sult, many individuals find themselves re­lying less on medication to manage the­ir condition.”

Kelsey Costa, a registered dietitian and nutrition consultant for the National Coalition on Healthcare who was not involved in the research, told Medical News Today it’s important that the study didn’t report any significant adverse events.

She explained how intermittent fasting works.

“This methodology is grounded on the principle of alternating between periods of feeding and fasting, consequently influencing nutrient metabolism, hormonal balance, and various physiological processes to improve cardiometabolic health,” Costa said.

Costa added that the fasting phase usually extends for 12 to 14 hours or more, when the body switches to utilizing stored fat and energy reserves as fuel, promoting weight loss.

“If has been shown to enhance metabolic flexibility, insulin sensitivity, and inflammation control, contributing to improved glycemic regulation and weight loss while fostering mindful eating habits and beneficial lifestyle alterations,” Costa said.

Ro Huntriss, a London-based registered dietician and the chief nutrition officer at diet and intermittent fasting app Simple, is even more optimistic about intermittent fasting.

“Significant weight loss can even put diabetes into remission whereby blood glucose levels return to normal levels,” Huntriss, who was not involved in the study, told Medical News Today. “Some studies suggest that intermittent fasting may have additional benefits when it comes to improving insulin resistance, making intermittent fasting an attractive option for people living with type 2 diabetes or prediabetes.

Huntriss acknowledged some downsides to intermittent fasting.

“It’s important to consider risks. Some people with diabetes may be prescribed medications that can allow blood glucose levels to fall too low,” Huntriss said. “This is a risk when making significant changes to your diet so it’s important to speak to your doctor before beginning a new diet if you have a condition such as type 2 diabetes, particularly for those on medication.”

“Intermittent fasting isn’t for everyone,” Huntriss said. “Intermittent fasting is not appropriate for those who are pregnant, breastfeeding, have a low body weight or have a history of eating disorders, so it’s really important to review your personal suitability of a diet before giving it a go.”

Dr. Theodore Strange, the chair of medicine at Staten Island University Hospital in New York who was not involved in the research, told Medical News Today the study was small “and so this needs to be taken to a larger scale.”

“I do think that there is some merit and there may be some advantages for the use of an intermittent fasting diet in the treatment specifically for type 2 diabetes in patients that are overweight and need to monitor caloric intake as part of the treatment plan,” Strange said.

“All diabetic patients need to consult with their physician prior to starting any diet, especially depending on their type of diabetes and medications,” he added. “There is an array of medications available to coincide with the type of diabetes and need to be taken appropriately.”