Newswise — NEW ORLEANS, LA: The first human test of early time-restricted feeding found that this meal-timing strategy reduced swings in hunger and altered fat and carbohydrate 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. The findings were unveiled during an oral presentation today at The Obesity Society Annual Meeting at ObesityWeek 2016 in New Orleans, Louisiana.
“Eating only during a much smaller window of time than people are typically used to may help with weight loss,” said Courtney Peterson, PhD, 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.”
This new research, funded by a TOS Early Career Research Grant awarded in 2014, 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 Dale Schoeller, PhD, FTOS spokesperson for The Obesity Society and Professor Emeritus at the University of Wisconsin. “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.”
Abstract and author contact information are available below.
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Outside Expert Dale Schoeller, PhD, The Obesity Society spokesperson and Professor Emeritus, Department of Nutritional Sciences at University of Wisconsin, Madison Contact: [email protected], 608-262-1082
Author Courtney Peterson, PhD, University of Alabama, Birmingham Contact: [email protected], 617-447-4168
Abstract Time-Restricted Feeding Increases Fat Oxidation and Reduces Swings in Appetite Levels in Humans
Background Time-restricted feeding (TRF) is a novel dietary intervention that involves eating in a narrow time period (typically < 9 hours), followed by a ≥15-hour daily fast. In rodent studies, TRF with an early eating period (eTRF) mitigates weight gain by increasing energy expenditure (EE). For the first time, we tested whether eTRF favorably affects energy metabolism in humans through changes in EE, macronutrient oxidation, and/or appetite.
Methods Overweight (BMI: 25-35 kg/m2) participants aged 20-45 years with no chronic disease were recruited. During each 1-week period of this randomized crossover study, participants kept a regular sleep schedule. Starting on Day 4, participants ate between 8 am and 2 pm (eTRF arm) or between 8 am and 8 pm (control arm). On Day 7, participants ate 3 identical meals according to their assigned schedule while undergoing 24-hour metabolic testing in a respiratory chamber, with concomitant measurements of appetite using VAS.
Results To date (Oct 2016), 11 participants have completed the study (7 M/4 F; mean±SEM; age: 32±2.4 years, BMI: 30.1±2.7 kg/m2). Linear mixed models reveal that eTRF did not affect overall 24-hour EE (1807±62 vs. 1789±62 kcal/day; p=0.69), despite increasing the thermic effect of food (TEF; p<0.05) relative to the control. However, eTRF changed the 24-hour patterns in the respiratory quotient (RQ; p=0.0002), indicating higher fat oxidation for several hours at night, in parallel with a trend towards increased protein oxidation (81.5±4.2 vs. 68.5±4.2 g/day; p=0.07). However, the differences in the 24-hour non-protein RQ (0.80±0.02 vs. 0.78±0.02; p=0.23) and hence in fat oxidation were not statistically significant likely due to low statistical power. Moreover, there were significant time by treatment interactions for EE, RQ, and TEF, reflecting differences in the 24-hour pattern of energy metabolism. Significant diurnal differences were also found for the daily swings in hunger and some serum markers (p<0.05).
Conclusions For the first time in humans, we report that eTRF lessens daily swings in hunger and changes the 24-hour pattern of fat oxidation and energy metabolism. It may therefore positively impact body composition.
Citation Peterson, C. Pennington Biomedical Research Center. Oral abstract presentation at: The Obesity Society Annual Meeting at ObesityWeekSM 2016; October 31 – November 4, 2016. http://www.obesityweek.com.
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