Scientists Tested an 8-Hour Eating Window and Found a Surprising Brain Benefit

Limiting the daily eating window may provide brain benefits beyond those associated with weight loss.

Eating within a shorter daily window may provide cognitive benefits beyond those associated with weight loss alone, according to results from a small clinical trial. The pilot study followed older women with overweight or obesity during a weight-loss program and found modest improvements on certain thinking tests among participants who compressed their daily eating period rather than only cutting calories.

"Losing weight alone will ward off some of the aging-related cognitive decline, and these data suggest that there may be additional benefits if you stop eating 4 hours prior to going to sleep and reduce food intake to 8-9 hours per day, compared to the usual eating window of 12 hours per day," said Sue Shapses, PhD, RD, DFASN, professor at Rutgers University and Rutgers-RWJ Medical Center, the study's Principal Investigator.

Shapses and her colleagues presented the results at NUTRITION 2026, the American Society for Nutrition's flagship annual meeting.

Lifestyle changes could alter dementia risk

As populations grow older, Alzheimer's disease and other forms of dementia are becoming increasingly common. Women and people with overweight or obesity generally face a greater likelihood of developing these conditions. Although diet and other lifestyle habits have been associated with dementia risk, relatively little research has tested whether changing those factors can lower it.

Two eating schedules put to the test

The trial included 47 women between ages 50 and 79 who had overweight or obesity. Every participant received guidance to reduce daily calorie intake by 500 calories. Of the group, 26 women were instructed to consume all food within fewer than nine hours each day, while the remaining participants continued eating across a typical window of about 12 hours. Those assigned to time-restricted eating generally ate between 10 a.m. and 6 p.m. Their average eating period was 8.2 hours per day, compared with 12.3 hours among women following the standard schedule.

A shorter window improves select skills

After six months, women in both groups had lost an average of approximately 15 pounds. Despite similar weight loss, participants eating within an 8-9 hour period showed significantly greater improvements in spatial planning and problem-solving than those maintaining a 12-hour window. They also tended to make fewer mistakes on tests of memory and learning, although that difference was not statistically significant. No meaningful differences appeared in multitasking ability or reaction time.

"There was a modest effect of time-restricted eating to improve spatial planning and problem-solving and on reducing errors related to memory and learning," said Shapses. "These outcomes suggest a better ability to remember information during everyday tasks and reducing mistakes related to memory, attention and problem-solving. Reductions in the eating window predicted greater improvements."

Larger trials must confirm the findings

Because the pilot study involved a small number of participants, the researchers emphasized that larger trials are necessary to verify the results. They also intend to examine possible biological explanations for the apparent benefits, including links among circadian rhythms, nutrient-sensing pathways, inflammation and metabolic health.