London: Restricting meals and snacks to a nine-hour daily window and avoiding food for at least four hours before bedtime may help protect cognitive function as people age, according to new research.
A pilot study involving older women living with overweight or obesity found that those who limited their eating to a shorter timeframe showed signs of improved mental performance compared with participants who spread their meals over a longer period.
Although the findings are preliminary and based on a small group of participants, researchers believe the approach could become a simple lifestyle strategy to help maintain brain health if confirmed by larger studies.
Professor Sue Shapses, a nutritional scientist at Rutgers University in New Jersey, said while weight loss itself can help slow cognitive decline, restricting eating to an eight- or nine-hour window and avoiding late-night meals may provide additional cognitive benefits.
Dementia remains the leading cause of death in the UK and the seventh leading cause worldwide, contributing to nearly two million deaths annually. While ageing and genetics cannot be changed, experts estimate that almost half of dementia cases could potentially be prevented or delayed through healthier lifestyle choices. Obesity during midlife is known to increase the risk of developing dementia later in life by around 30 percent.
Clinical Trial
The six-month clinical trial included 47 women aged between 50 and 79 who were overweight or obese. All participants reduced their daily calorie intake by 500 calories. Of them, 26 were instructed to consume all meals within a nine-hour window, typically between 10 a.m. and 6 p.m., while the remaining participants ate over an average 12-hour period.
By the end of the study, both groups had lost a similar amount of weight, averaging around 7 kilograms (15 pounds). However, participants following the restricted eating schedule performed better in tests measuring spatial planning and problem-solving skills.
They also showed signs of making fewer mistakes in memory and learning tasks, although no major differences were observed in multitasking or reaction-time assessments.
Improved memory
Presenting the findings at Nutrition 2026, the annual meeting of the American Society for Nutrition in Maryland, Shapses described the improvements as modest but encouraging. The Professor added that the results indicate that time-restricted eating may help people remember information needed for everyday activities while reducing errors related to attention, memory, and problem-solving.
The research team now plans to investigate why meal timing may influence brain health, exploring how circadian rhythms, metabolism, and inflammation interact to affect cognitive function.
Researchers noted that many people in countries such as the UK and the US typically eat over a 14-hour period, leaving only about 10 hours overnight without food. Previous research has suggested that extending overnight fasting offers several health benefits.
A review published in January found that finishing meals before 7 pm was associated with improvements in body weight, body mass index (BMI), waist circumference, blood pressure, and other markers of metabolic health.
Professor Wendy Hall, Head of Nutritional Sciences at King’s College London, who was not involved in the study, noted that the findings are biologically plausible.
Hall explained that limiting eating to a shorter daily window may support cognitive health in middle-aged and older adults with overweight by improving weight management while also enhancing blood sugar regulation, vascular health, and reducing inflammation through avoiding large evening meals.
However, Hall stressed that the results remain preliminary and should be interpreted cautiously until the full peer-reviewed study is published to determine whether the observed improvements are clinically significant.
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