The first human test of early time-restricted feeding found that this meal-timing strategy reduced swings in hunger and altered fat and carb burning patterns, which may help with losing weight. In early time-restricted feeding (eTRF), people eat their last meal by the mid-afternoon and don't eat again until breakfast the next morning.
"Eating only during a much smaller window of time than people are typically used to may help with weight loss," said Courtney Peterson, who led the study at Pennington Biomedical Research Center.
"We found that eating between 8 am and 2 pm followed by an 18-hour daily fast kept appetite levels more even throughout the day, in comparison to eating between 8 am and 8 pm, which is what the median American does," added Peterson.
This new research suggests that eating a very early dinner, or even skipping dinner, may have some benefits for losing weight. The body has a internal clock, and many aspects of metabolism are at their optimal functioning in the morning. Therefore, eating in alignment with the body's circadian clock by eating earlier in the day can positively influence health, and this new study of eTRF shows that this also applies to metabolism. This first test of eTRF in humans follows rodent studies of this approach to weight loss, which previously found that eTRF reduced fat mass and decreased the risk of chronic diseases in rodents.
To conduct their study, Dr. Peterson and colleagues followed eleven men and women with excess weight over four days of eating between 8am and 2pm (eTRF), and four days of eating between 8am and 8pm (average feeding for Americans). The researchers then tested the impact of eTRF on calories burned, fat burned and appetite. To eliminate subjectivity, the researchers had all participants try both eating schedules, eat the same number of calories both times, and complete rigorous testing under supervision.
The researchers found that although eTRF did not affect how many calories participants burned, it reduced daily hunger swings and increased fat burning during several hours at night. It also improved metabolic flexibility, which is the body's ability to switch between burning carbs and fats. Whether eTRF helps with weight loss or improves other aspects of health is still unknown.
"These preliminary findings suggest for the first time in humans what we've seen in animal models -- that the timing of eating during the day does have an impact on our metabolism," said researcher Dale Schoeller. "With additional research on early-time restricted feeding on humans, we can create a more complete picture of whether this innovative method can best help prevent and treat obesity."
The findings were unveiled recently during an oral presentation at The Obesity Society Annual Meeting at ObesityWeek 2016 in New Orleans, Louisiana.