Keep All Daily Meals to a 9-Hour Window to Cut Dementia Risk

By the Editorial Team · Monday, July 27, 2026

Researchers at Rutgers University found that overweight women who limited their eating to a nine-hour daily window and avoided food in the four hours before bedtime showed improved cognitive function compared to those who ate over a longer period. These findings suggest that time-restricted eating, beyond calorie reduction, may help lower dementia risk by potentially enhancing brain health through effects on circadian rhythms.

A time-restricted eating pattern that limits food consumption to a nine-hour window during the day and avoids eating in the four hours before bedtime may be associated with improved cognitive function and a potentially reduced risk of dementia in overweight women, according to researchers from Rutgers University in New Jersey.

The findings come from a small randomized clinical trial involving 47 women aged 50 to 79 classified as overweight or obese. All participants were placed on a calorie-restricted diet, reducing their daily intake by 500 calories. Of these, 26 were also instructed to confine their eating to approximately a nine-hour period, typically between 10 a.m. and 6 p.m., resulting in an average eating window of 8.2 hours. The remaining participants continued to eat over a usual daily span averaging 12 to 12.3 hours.

After six months, both groups showed similar weight loss, averaging around 6.8 kg (15 pounds), with no significant difference between those following time-restricted eating and those eating over a longer period. However, cognitive assessments revealed that women in the time-restricted group demonstrated notable improvements in spatial planning and problem-solving skills. Additionally, there was a tendency toward fewer errors in memory and learning tasks compared with the control group. No significant differences were observed in multitasking ability or reaction time.

The researchers, led by Dr. Sue Shapses, emphasized that while weight loss itself is linked to reduced cognitive decline and dementia risk, restricting eating times may provide additional benefits. They hypothesize that time-restricted eating could influence circadian rhythms—the body’s internal clock regulating sleep, hormone release, and metabolism—which in turn might impact brain health.

Dementia, a progressive neurodegenerative condition affecting memory and cognitive abilities, is a significant cause of mortality and disability worldwide, with obesity in middle age recognized as a modifiable risk factor that increases the likelihood of developing the disease. The trial’s outcomes suggest that alongside dietary calorie control, adjusting when people eat may be an important lifestyle consideration for reducing dementia risk.

Experts not involved with the study highlighted the potential of time-restricted eating to improve metabolic health and reduce factors such as inflammation and blood sugar fluctuations, which could contribute to brain health. However, they also noted that these results are preliminary and that further research with larger and more diverse populations is necessary to confirm and clarify the clinical significance of the findings.

The researchers plan to continue investigating the mechanisms behind the cognitive benefits observed, including the roles of circadian biology, inflammation, and metabolic processes. The study was presented during the American Society for Nutrition’s annual conference in Maryland.

While intermittent fasting and related dietary patterns have garnered increasing scientific interest in recent years, medical professionals caution that individuals should consult healthcare providers before making significant changes to eating schedules, especially in older populations or those with underlying health conditions.

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