Intermittent fasting could help people with pre-diabetes and obesity control their blood sugar, a small study suggests

• Researchers studied the blood sugar of people with pre-diabetes and obesity while they intermittent fasted.
• Eating 80% of a day's calories before 1pm appeared to help control their blood sugar levels.

Eating earlier in the day could help people with pre-diabetes and obesity control their blood sugar levels, according to new research.

The study, which has not been published in a journal, was presented at the Endocrine Society's annual meeting in Chicago, ENDO 2023, on Thursday.

Researchers assessed the effect of early time-restricted feeding — a type of intermittent fasting where participants only eat for the first six to eight hours of the day — on participants' blood sugar levels.

The research comes off the back of previous studies that suggested this form of intermittent fasting may improve cardiometabolic health and blood sugar levels. The researchers wanted to determine whether this was due to the weight loss that this fasting strategy can cause or the fasting itself.

Participants in the study ate 80% of their calories before 1pm

10 participants with prediabetes and obesity were observed as part of the study.

Half of the patients were put on the eTRF diet and consumed 80% of their calories before 1 pm, while the others ate 50% of calories after 4pm, to mimic a more traditional style of eating. After a week, the patients swapped over to the other diet for the second week.

The researchers gave the participants food so their weight didn't change and potentially skew the results.

The team found that eTRF, for even just a week, appeared to prevent fluctuations in blood glucose levels and decrease the time that blood glucose is above the range it should be, independent of a person's weight.

Dr. Joanne Bruno, endocrinology fellow at NYU Langone Health who led the research, said that this suggests eTRF may be a "helpful strategy for those with prediabetes or obesity to keep their blood sugars in a normal range and prevent them from progressing to type 2 diabetes."

The team said more research needs to be done to understand the potential benefits of eTRF.

Intermittent fasting isn't suitable for everyone

Insider previously reported that intermittent fasting in general isn't suitable for everyone, particularly those who are under age 18, pregnant, breastfeeding, have struggled with eating disorders in the past, are over 65, or have type 2 diabetes. It's also best avoided by those trying to gain or maintain muscle. Anyone who wants to try it should consult their doctor first.

David Clayton, a lecturer in nutrition and exercise physiology who researches intermittent fasting at Nottingham Trent University, UK, who wasn't involved in the study, told Insider: "Early in the day our bodies are more primed for using glucose as a fuel source."

For this reason, it is better to eat a big breakfast in the morning and smaller meals throughout the rest of the day, or fast in the evening, he said. Clayton said that skipping breakfast regularly has been linked to having a higher BMI.

"If you are backloading all your calories to the evening, then you're probably putting your body under a little bit more stress to use that glucose," he said, which may, over the course of several years, contribute to developing type 2 diabetes.

Clayton said that eating earlier in the day is something that the average person can adopt and it can be beneficial to their health, but people with obesity or pre-diabetes have the most to gain from trying this type of fasting.

While fasting in the evening can work for some, Clayton said simply eating less in the evening can be beneficial to others, particularly those who eat together as a family in the evening.

For these people, even just eating fewer carbohydrates at dinnertime meal can help, he said.