Older women who restricted their daily food intake to across roughly eight or nine hours showed modest improvements in certain thinking skills compared with those who ate across a longer period, even though both groups lost similar amounts of weight, according to preliminary results from a small U.S. clinical trial presented Sunday.
Researchers at Rutgers University enrolled 47 women ages 50 to 79 who were overweight or obese in a six-month weight loss program.
All participants received counseling to cut about 500 calories from their daily diets.
Twenty-six of them were also instructed to eat only within a window of less than nine hours each day, typically between 10 a.m. and 6 p.m. Their average eating period was 8.2 hours.
The remaining women continued with a more conventional schedule averaging 12.3 hours.
After six months, both groups had lost an average of about 7 kilograms (15 pounds).
Women in the shorter eating-window group performed significantly better on tests of spatial planning and problem-solving. They also tended to make fewer mistakes on memory and learning assessments, though that difference did not reach statistical significance. No clear differences appeared on measures of reaction time or multitasking.
"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 prior to going to sleep and reduce food intake to eight to nine hours per day, compared to the usual eating window of 12 hours per day,” said Sue Shapses, professor of nutritional sciences at Rutgers and the study’s principal investigator.
Shapses described the cognitive effects as modest and noted that shorter eating windows predicted greater improvements.
The findings were presented at Nutrition 2026, the annual meeting of the American Society for Nutrition.
