Confining meals to a shorter eating window may sharpen memory and problem-solving in later life, independent of weight loss

Confining meals to a nine-hour daily window and ceasing to eat at least four hours before bedtime could help stave off dementia, according to a clinical trial being unveiled today at NUTRITION 2026, the American Society for Nutrition's annual conference near Washington, DC.

The pilot study, led by Professor Sue Shapses of Rutgers University, examined older women carrying excess weight and discovered those who narrowed their eating hours showed sharper cognitive performance than participants who did not.

Crucially, these mental benefits appeared to go beyond the positive effects of shedding pounds alone, pointing to something distinctive about when we eat rather than simply how much.

The trial recruited 47 women between 50 and 79 years of age, all classified as overweight or obese. Every participant received guidance to cut their daily caloric intake by 500 calories.

Of the group, 26 women were instructed to compress their food consumption into fewer than nine hours each day. The remaining 21 continued eating across a conventional window of roughly 12 hours.

Those on the restricted schedule typically consumed their meals between 10am and 6pm, averaging 8.2 hours of daily eating. By contrast, the control group averaged 12.3 hours. The programme ran for six months in total.

Across both groups, participants shed approximately 15 lbs (6.8kg) on average over the half-year period. Yet those eating within the tighter window outperformed their counterparts on tests measuring spatial planning and problem-solving abilities.

They also made fewer mistakes in assessments of memory and learning. However, no meaningful difference emerged in multitasking or reaction time.

"There was a modest effect of time-restricted eating to improve spatial planning and problem-solving and to reduce errors related to memory and learning," Professor Shapses said.

"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."

Researchers acknowledged larger trials will be necessary to verify these findings.

They also expressed interest in exploring the mechanisms behind time-restricted eating's cognitive advantages, including its relationship with circadian rhythm, nutrient-sensing pathways, inflammatory responses and broader metabolic health.

"Losing weight alone will ward off some of the ageing-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," Professor Shapses said.

The research carries particular resonance on this side of the Atlantic. The Alzheimer's Society estimates 982,000 people in Britain currently live with dementia, a figure projected to climb to 1.4 million by 2040 amid the UK's ageing population.