Limiting Daily Food Intake to 8-9 Hours May Boost Cognitive Function in Older Women

A recent clinical trial suggests that eating within a shorter daily window may give the aging brain a modest boost beyond weight loss alone. The study, which was presented at the annual flagship meeting of the American Society for Nutrition, found that older women who limited their food intake to 8-9 hours per day showed greater improvement on certain thinking tests than those who spread their meals across 12 hours.

The pilot study followed 47 women aged 50-79 who had overweight or obesity and were participating in a six-month weight loss program. Each participant received guidance to cut daily calorie intake by 500 calories. Twenty-six women were also instructed to consume all food within a period of less than nine hours each day, while the remaining participants continued eating across a more typical daily period of about 12 hours.

Women in the time-restricted eating group generally consumed food between 10 a.m. and 6 p.m., with an average eating period of 8.2 hours per day. Their performance on tests measuring spatial planning and problem-solving was significantly better than that of the standard eating group, which had an average eating period of 12.3 hours. The time-restricted group also tended to make fewer mistakes on tests involving memory and learning, although that difference did not reach statistical significance.

Lead researcher Sue Shapses, PhD, RD, DFASN, professor at Rutgers University and Rutgers-RWJ Medical Center, emphasized that the trial was small and that larger studies will be necessary to determine whether the cognitive improvements can be confirmed in a broader population. The team also plans to examine why meal timing might affect the brain, with possible explanations including interactions among circadian rhythm, inflammation, metabolic health, and the biological pathways that help the body sense and respond to nutrients.

While the findings are preliminary, they offer promising insights into the potential benefits of time-restricted eating for older adults. As the global population ages, it is essential to identify effective strategies for promoting healthy aging and reducing the risk of age-related cognitive decline.

Alzheimer’s disease and other forms of dementia are becoming more common as populations grow older. Women and people with overweight or obesity also tend to have a greater risk of developing these conditions. Researchers have long studied how diet and other lifestyle habits relate to dementia risk, but relatively few trials have tested whether changing these behaviors can directly reduce that risk.

The new trial included women who had overweight or obesity and were participating in a six-month weight loss program. Each participant received guidance to cut daily calorie intake by 500 calories. Twenty-six women were also instructed to consume all food within a period of less than nine hours each day, while the remaining participants continued eating across a more typical daily period of about 12 hours.

Women in the time-restricted eating group generally consumed food between 10 a.m. and 6 p.m., with an average eating period of 8.2 hours per day. Their performance on tests measuring spatial planning and problem-solving was significantly better than that of the standard eating group, which had an average eating period of 12.3 hours.

Despite comparable weight loss results, the women who ate within an eight- to nine-hour period performed significantly better on tests measuring spatial planning and problem-solving than those who continued eating across 12 hours. The time-restricted group also tended to make fewer mistakes on tests involving memory and learning, although that difference did not reach statistical significance.

The researchers emphasized that the trial was small and that larger studies will be necessary to determine whether the cognitive improvements can be confirmed in a broader population. The team also plans to examine why meal timing might affect the brain, with possible explanations including interactions among circadian rhythm, inflammation, metabolic health, and the biological pathways that help the body sense and respond to nutrients.