A nine-hour daily eating window may help support certain aspects of brain function in older women with overweight or obesity, according to research presented at Nutrition 2026.
The study found that participants who limited their food intake to roughly eight to nine hours a day showed improvements in spatial planning and problem-solving after six months compared with women who continued eating across a roughly 12-hour window.
The findings are preliminary and do not establish that time-restricted eating can prevent dementia or slow cognitive decline. The study involved just 47 women, making larger and longer-term research necessary to determine whether the apparent cognitive benefits are meaningful and lasting.
The Eating Schedule That May Have Made a Difference
Researchers at Rutgers University studied women ages 50 to 79 who were living with overweight or obesity. All participants were asked to reduce their daily calorie intake by about 500 calories for six months.
Twenty-six women followed time-restricted eating, consuming their meals within a self-selected window of no more than nine hours. The eating period typically ran from about 10 a.m. to 6 p.m., with participants avoiding food for several hours before bedtime. The remaining 21 women reduced their calorie intake but maintained their usual eating schedule, which lasted about 12 hours.
Both groups lost a similar amount of weight, averaging about 7.5 kilograms in the time-restricted eating group and 6.1 kilograms in the calorie-restriction group.
But cognitive testing revealed differences in some areas.
Women following the shorter eating window performed better over time on tests measuring spatial planning and problem-solving. They also made fewer errors on a memory and learning assessment, although the difference between the two groups was not statistically significant for that measure.
Other tests involving multitasking and reaction speed did not show meaningful changes.
Why Meal Timing Could Matter for the Brain
Researchers say the potential cognitive effects may extend beyond weight loss.
The body's circadian rhythm regulates numerous biological processes, including metabolism, sleep and hormone activity. Eating over a prolonged period, particularly late at night, may disrupt these daily biological patterns, while extending the overnight fasting period could potentially improve metabolic health.
The researchers suggested that changes in metabolism, inflammation and circadian biology may help explain why shortening the eating window was associated with improvements in some cognitive measures.
Time-restricted eating could potentially benefit cognitive health in older adults with overweight, partly through effects on weight management, blood sugar control, vascular function and inflammation.
Still, researchers and experts cautioned that the findings are preliminary and that comprehensive peer-reviewed research is needed to determine whether the observed improvements are clinically significant.
The Dementia Question Remains Unanswered
The findings come as researchers continue examining modifiable factors that may influence dementia risk. Age and genetics remain important, unchangeable risk factors, but scientists have increasingly focused on lifestyle and metabolic health as potential avenues for prevention.
Obesity during midlife has been associated with a higher risk of dementia later in life, making strategies that improve weight and metabolic health an active area of research.
However, the new study should not be interpreted as evidence that eating within a nine-hour window prevents dementia. The trial was small, included only women with overweight or obesity and lasted six months.
The researchers also did not determine exactly why the eating schedule was associated with better performance on some cognitive tests.
Further studies will need to establish whether the findings can be replicated in larger, more diverse populations and whether the benefits persist over time. For now, the research offers an early clue that when people eat, not just what they eat or how much, could be relevant to brain health as they age.
