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The first human test of early time-restricted feeding is showing that this meal-timing strategy may help reduce swings in hunger and altered fat- and carbohydrate-burning patterns.

In early time-restricted feeding (eTRF), individuals eat their last meal by the mid-afternoon and do not eat again until breakfast the next morning. In a new study presented at ObesityWeek 2016, researchers found that eating only during a much smaller window of time than people are typically used to may help with weight loss.


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Courtney Peterson, PhD, MSc, assistant professor in the department of nutrition sciences at the University of Alabama at Birmingham, and colleagues found that eating between 8 am and 2 pm followed by an 18-hour daily fast kept appetite levels more even throughout the day compared with eating between 8 am and 8 pm. 

The findings suggest that eating a very early dinner, or even skipping dinner, may have some benefits for losing weight. The body has an internal clock, and many aspects of metabolism are at their optimal functioning in the morning. It is theorized that eating in alignment with the body’s circadian clock by eating earlier in the day may positively influence health.

The current study of eTRF suggests this eating pattern may affect 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.

Dr Peterson and colleagues conducted a study with 11 men and women with excess weight. The study participants had a BMI between 25 and35 kg/m2 (mean BMI: 30.1 kg/m2) and were between aged 20 to 45 years (mean age: 32 years). All participants were followed over 4 days of eating between 8 am and 2pm (eTRF), and 4 days of eating between 8 am and 8 pm (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, consuming the same number of calories both times, and completing 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.

“We found that early time-restricted feeding (eTRF) increases fat oxidation for several hours at night, although the increase in total daily fat oxidation was not significant. However, eTRF did improve metabolic flexibility, which is the ability to switch between burning carbohydrates and fat. Other studies show that metabolic flexibility is impaired in insulin-resistant individuals. So since eTRF increases metabolic flexibility, this may be beneficial for health,” Dr Peterson told Endocrinology Advisor

She said eTRF does improve weight loss in rodents, but it is too early to say yet whether early time-restricted feeding will improve weight loss in humans. If eTRF does improve weight loss or fat loss in humans, it looks like eTRF would do so by reducing food intake or by increasing fat oxidation and not by increasing the number of calories burned, according to Dr Peterson. 

“The surprising thing we found is that participants were not hungrier on average on eTRF, even though we had them fast daily for 18 hours. So, we overturned the belief that fasting for a longer period each day (when the same number of total calories are eaten) intrinsically makes a person hungrier. Moreover, we found contrary to our expectation, that eTRF kept hunger levels more even throughout the day (smaller swings in hunger), which again, may provide a benefit in losing weight,” said Dr Peterson.

Dale Schoeller, PhD, a spokesperson for The Obesity Society and professor emeritus at the University of Wisconsin, said with additional research on eTRF on humans, it may be possible to create a more complete picture of whether this approach can help with combating obesity.  

“This is one of the first studies of time restricted feedings in humans and it is also a preliminary report based on the first 11 subjects of what is expected to be a larger study. Animal studies and these early data do indicate that time restricted feeding will have benefits,” Dr Schoeller told Endocrinology Advisor.

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Reference

  1. Peterson C, Poggiogalle E, Hsia D, Ravussin E. Time-restricted feeding increases fat oxidation and reduces swings in appetite levels in humans. Abstract T-OR-2081. Presented at: ObesityWeek 2016; October 31-November 4, 2016; New Orleans, LA.

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This article originally appeared on Endocrinology Advisor