As intermittent fasting, in which people eat only within a fixed and predefined time window, continues to gain popularity, studies show it may have even more benefits than initially thought. One study, published in the medical journal Clinical Nutrition, found that 16:8 intermittent fasting — meaning eight hours in which eating is allowed and 16 hours of fasting — may help not only with weight loss, but also with maintaining the results over time.
Gallery
Intermittent fasting: not just how long you fast, but also when you eat
(Photo: Shutterstock)
The study included people ages 30 to 60 who were overweight or obese. For 12 weeks, they ate within an eight-hour window each day, while also receiving guidance on a Mediterranean diet. The results showed that even after one year, weight loss among participants in the intermittent fasting groups was greater than in the control group, even though they were no longer required to follow defined eating hours.
Not only how many hours — but also when you eat
“Weight loss itself helps slow some of the cognitive decline associated with aging,” explained Professor Sue Shapses of Rutgers University, who led the study. “However, data suggest that reducing the eating window to 8 to 9 hours a day and stopping eating four hours before bedtime may provide additional benefits compared with a standard 12-hour eating window.” The findings were published ahead of their presentation at the annual meeting of the American Society for Nutrition.
Experts say that in any weight-loss process it is important to consume enough protein and combine it with strength training in order to minimize muscle loss as much as possible. An early eating window may be a more cautious choice for those who want to preserve body mass. However, it is still unclear what is behind this advantage: the timing of eating itself, its alignment with the biological clock or the fact that people who eat earlier consume fewer calories.
Benefits also for brain activity
The possible effect of limiting eating hours is not limited to weight and body composition. Another clinical trial found that a shorter eating window may also have a positive effect on the brain, and may even help reduce the risk of dementia. The trial was conducted among older women who were overweight or obese and participated in a weight-loss program. Women who reduced their daily eating window showed a slight improvement in several cognitive abilities compared with women who only reduced their calorie intake.
Reducing eating hours may also affect cognitive function
(Photo: Shutterstock)
“Weight loss itself helps slow some of the cognitive decline associated with aging,” explained Professor Sue Shapses of Rutgers University in the U.S., who led the study. “However, our data suggest that reducing the eating window to 8 to 9 hours a day and stopping eating four hours before bedtime may provide additional benefits compared with a standard 12-hour eating window.” The findings were published ahead of their presentation at the annual meeting of the American Society for Nutrition.
As the population ages, Alzheimer’s disease and other types of dementia are becoming more common. Women and people who are overweight or obese are at higher risk of developing these diseases. Diet and lifestyle habits have previously been linked to dementia risk, but so far, few studies have examined whether changing those habits can actually reduce the risk.
The American trial included 47 women ages 50 to 79 who were overweight or obese. All participants were asked to cut 500 calories from their daily intake. Twenty-six of them were instructed to eat within a window of less than nine hours a day, usually between 10 a.m. and 6 p.m., while the rest continued eating within a standard window of about 12 hours. In practice, the average eating window in the first group lasted 8.2 hours, compared with 12.3 hours in the second group.
A short eating window may help maintain weight
(Photo: Shutterstock)
After six months, participants in both groups lost an average of nearly 7 kilograms (15.4 pounds). However, the women who ate within an 8- to 9-hour window achieved better results in tests that examined spatial planning and problem-solving compared with women who ate within a window of about 12 hours.
They also tended to make fewer mistakes on memory and learning tests, but that difference was not statistically significant. No significant difference was found between the groups in tests examining the ability to perform several tasks simultaneously or in reaction times.
“We identified a moderate effect of time-restricted eating on spatial planning and problem-solving ability, along with a decline in the number of errors related to memory and learning,” Shapses added. “The results point to a better ability to remember information during daily tasks, and to fewer errors related to memory, attention and problem-solving. The greater the reduction in the eating window, the greater the improvement observed.”
The researchers stress that additional studies involving larger numbers of people are needed to confirm the findings. In the next stage, they plan to examine which biological mechanisms may explain these benefits, including the connection to the biological clock, the way the body identifies and responds to nutrients, inflammatory processes and metabolic health.