Eating within 8 hours may help keep the aging brain sharp

The pilot study followed women with overweight or obesity who were participating in a six-month weight loss program. Those who ate within a daily window of roughly eight to nine hours showed greater improvement on certain thinking tests than participants who spread their meals across about 12 hours.

"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 annual flagship meeting of the American Society for Nutrition, held July 25-28 in National Harbor, Maryland, outside Washington, D.C.

Meal Timing and Dementia Risk

Alzheimer's disease and other forms of dementia are becoming more common as populations grow older. Women and people with overweight or obesity also tend to have a greater risk of developing these conditions.

Researchers have long studied how diet and other lifestyle habits relate to dementia risk. However, relatively few trials have tested whether changing these behaviors can directly reduce that risk.

The new trial included 47 women ages 50 to 79 who had overweight or obesity. Each participant received guidance to cut daily calorie intake by 500 calories.

Twenty-six women were also instructed to consume all food within a period of less than nine hours each day. The remaining participants continued eating across a more typical daily period of about 12 hours.

Women in the time-restricted eating group generally consumed food between 10 a.m. and 6 p.m. Their average eating period was 8.2 hours per day, compared with an average of 12.3 hours among women in the standard eating group.

Similar Weight Loss but Different Cognitive Results

After six months, the women had lost an average of approximately 15 pounds. Weight loss was similar in both groups.

Despite those comparable results, the women who ate within an eight- to nine-hour period performed significantly better on tests measuring spatial planning and problem solving than those who continued eating across 12 hours.

The time-restricted group also tended to make fewer mistakes on tests involving memory and learning, although that difference did not reach statistical significance. Researchers found no significant differences between the groups on tests of reaction time or multitasking.

"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."

Why a Shorter Eating Window Might Help

The researchers emphasized that the trial was small and that larger studies will be necessary to determine whether the cognitive improvements can be confirmed in a broader population.

Future research will also examine why meal timing might affect the brain. Possible explanations include interactions among circadian rhythm, inflammation, metabolic health, and the biological pathways that help the body sense and respond to nutrients.

The team presented the research on Sunday, July 26, during the Aging and Chronic Disease (II) Poster Session at the Gaylord National Resort & Convention Center (abstract).

The findings should be regarded as preliminary. Abstracts presented at NUTRITION 2026 were reviewed and chosen by a committee of experts, but they generally have not completed the full peer review process required for publication in a scientific journal.