Results from a small clinical trial suggest it may be possible to reduce the risk of dementia by eating during fewer hours of the day. The pilot study, which involved a weight-loss program for older women with overweight or obesity, showed modest cognitive improvements among those who limited their daily eating window instead of just reducing their calorie intake.
“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 four hours before going to sleep and reduce food intake to 8–9 hours per day, compared with the usual eating window of 12 hours per day,” said Sue Shapses, Ph.D., RD, DFASN, professor at Rutgers University and Rutgers-RWJ Medical Center and the study’s principal investigator.
Shapses’ group will present the findings at NUTRITION 2026, the flagship annual meeting of the American Society for Nutrition, held July 25–28 in National Harbor, Maryland, just outside Washington, D.C.
Who was in the trial
Alzheimer’s disease and other forms of dementia have become more prevalent as populations age, and women and people who are overweight or obese tend to face a higher likelihood of developing these conditions. Diet and other lifestyle factors have been linked to dementia risk, but few studies have examined whether modifying these factors can reduce that risk.
The trial enrolled 47 women ages 50–79 who were overweight or obese. All participants were counseled to reduce their calorie intake by 500 calories per day. Twenty-six participants were asked to restrict their eating to a window of less than nine hours per day, while the rest maintained a typical eating window of about 12 hours per day.
In the time-restricted eating group, participants generally ate only between 10 a.m. and 6 p.m., with an average daily eating window of 8.2 hours, compared with an average of 12.3 hours per day among those asked to maintain the standard eating window.
Cognitive gains despite similar weight loss
After six months, participants had lost about 15 pounds (6.8 kilograms), on average, about the same in both groups. Compared with participants who maintained a 12-hour eating window, those who consumed food for only 8–9 hours per day showed significant improvements in spatial planning and problem-solving at the end of the weight-loss program. They also showed a trend toward fewer errors on memory and learning tests, but there was no significant difference in performance on multitasking or reaction-time tests.
“There was a modest effect of time-restricted eating on improving spatial planning and problem-solving and reducing errors related to memory and learning,” said Shapses. “These outcomes suggest a better ability to remember information during everyday tasks and fewer mistakes related to memory, attention and problem-solving. Reductions in the eating window predicted greater improvements.”
Clues the team wants to test
The researchers said further studies would be needed to confirm the findings in a larger group of participants. They also plan to investigate mechanisms that might explain the possible benefits of time-restricted eating, such as interactions among circadian rhythms, nutrient-sensing pathways, inflammation and metabolic health. https://medicalxpress.com/news/2026-07-restricted-retain-cognitive-function-older.html
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