Restricted eating hours may reduce cognitive decline in older age, researchers find | Ageing
Limiting mealtimes and snacks to a nine-hour window and avoiding food for four hours before bed may help prevent cognitive decline in later life, researchers say.
A pilot study of older women living with overweight or obesity found hints of improved mental abilities in those who ate within a limited period of time, compared to those who spread out their meals over a longer period of time.
This finding is preliminary considering the numbers in the study, but if confirmed in larger studies, the study suggests that people may help preserve their cognitive abilities by eating within a relatively narrow window and not eating until late at night.
Prof Sue Shapses, a nutritional scientist at Rutgers University in New Jersey, US, said weight loss alone could help slow cognitive decline in later life, but there could be “additional benefits” for people who do not eat outside the eight to nine hour window and stop eating four hours before bed.
Dementia is the leading cause of death in the UK, the seventh worldwide and causes around 2 million deaths worldwide each year. Some risk factors, such as age and genetics, are unavoidable, but experts believe that almost half of cases can be prevented or delayed with lifestyle changes. Obesity in midlife can increase the risk of dementia in later life by 30%.
Shapses conducted a small clinical trial in which 47 women ages 50 to 79 who were overweight or obese were encouraged to reduce 500 calories from their daily diet for six months. The 26 people in the group were advised to only eat within a nine-hour period. Typically this means eating between 10 a.m. and 6 p.m., while the rest of the volunteers spread their meals out over about 12 hours.
At the end of the trial, both groups experienced similar weight loss, averaging around 7 kg (15 lbs). But cognitive tests found that those who restricted eating to a narrow window performed better than others on tests of spatial planning and problem-solving. There were also hints that they made fewer errors on memory and learning tests, but both groups performed about the same on some multitasking and reaction time tests.
Shapses called the effects “modest” but said they suggest that time-restricted eating may improve people’s ability to recall information for daily tasks and reduce errors associated with memory, attention and problem solving. The details were: presented at Nutrition 2026, the annual meeting of the American Society of Nutrition in Maryland.
Researchers now plan to investigate why it might be important to consider when we eat as well as what we eat. Benefits drivable through the complex interplay of circadian rhythms, metabolism, and inflammation.
In many countries, including the UK and the US, it is common to eat over a 14-hour period, leaving only 10 hours without food during the night. However, research clearly demonstrates the health benefits of extending overnight fasting. A review published in January found that finishing a meal before 7 p.m. was associated with significant improvements in body weight, BMI, waist circumference, blood pressure and markers of metabolic health.
Professor, head of nutritional sciences at King’s College London, who was not involved in the research. Wendy Hall said limiting mealtimes to a narrow window may benefit the brain.
“Time-restricted eating is a reasonable approach to support cognitive health in overweight middle-aged and older adults, not only because it may aid weight management but also because avoiding large meals late in the evening may improve blood sugar control, vascular function, and inflammation,” he said.
Hall cautioned that the findings are preliminary and that it is important to see the full peer-reviewed study to determine whether any improvements are clinically meaningful.
