A six-month trial of older women suggests that compressing daily meals into a tight eight-hour window produces cognitive gains that weight loss alone cannot explain. The finding adds a new dimension to how timing of food intake might protect mental sharpness in aging.
Researchers at Rutgers University tracked 47 women ages 50 to 79 with overweight or obesity. All participants cut their daily calories by 500 to lose weight. But half the group also had to finish eating by around 6 p.m. after starting at 10 a.m., squeezing their meals into roughly 8.2 hours. The control group ate across a typical 12.3-hour window.
After six months, both groups had shed about 15 pounds on average. Yet the women who ate within the tighter window performed measurably better on spatial planning and problem-solving tests. They also made fewer mistakes on memory and learning tasks, though that difference fell short of statistical significance.
"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, the study's principal investigator and a professor at Rutgers University and Rutgers-RWJ Medical Center.
The research emerged at the American Society for Nutrition's annual meeting in July. It addresses a gap in dementia science: while doctors know that diet influences brain health, few controlled trials have tested whether changing eating patterns directly slows cognitive decline. Women and people carrying extra weight both face higher dementia risk, making this population particularly relevant.
The mechanism behind the effect remains unclear. Researchers speculate that the timing of eating may interact with circadian rhythms, inflammation levels, metabolic health, and how the body senses and processes nutrients. A narrower eating window might allow the digestive system and brain to operate on a more synchronized schedule.
Shapses cautioned that the trial was small and preliminary, and that peer review has not yet begun. Larger studies will be needed to confirm whether the cognitive bump holds across different populations and age groups. Reaction time and multitasking showed no differences between the groups, suggesting the effect targets specific cognitive domains rather than broad mental performance.
Author Jessica Williams: "This is intriguing early evidence, but calling it a brain-saver at this stage would be premature."
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