NEW ORLEANS — Restricting food intake to a 6-hour window may help facilitate weight loss, primarily by affecting hunger, according to data from the first trial of time-restricted feeding in humans.
“Eating dinner by mid-afternoon (early time-restricted feeding) does not appear to affect how many calories you burn,” presenter Courtney Peterson, PhD, of Pennington Biomedical Research Center, told Endocrine Today. “However, it may keep hunger levels more even across the day, and it does improve metabolic flexibility and change the daily patterns in fat oxidation, particularly by increasing fat oxidation during several hours at night.”
In this randomized crossover study, Peterson and colleagues enrolled 11 participants (7 men) aged 20 to 45 years with BMI between 25 and 35 kg/m2 (mean BMI 30.1 kg/m2) to undergo two week-long feeding arms. On day 4 of each week, participants were allowed to eat between 8 a.m. and 2 p.m. in the time-restricted eating group; those in the control group were allowed to eat between 8 a.m. and 8 p.m. On day 7, participants ate identical meals according to their assigned schedules and underwent 24-hour metabolic testing in a respiratory chamber; appetite was assessed with a visual analogue scale.
The two meal schedules yielded similar energy expenditure values. However, 24-hour patterns in the respiratory quotient revealed greater fat oxidation overnight (P = .07) and a trend toward greater protein oxidation during the restricted feeding week.
“Many people assume that fasting for 18 hours daily (by finishing dinner in the mid-afternoon) would leave someone ravenous at night,” Peterson said. “However, we did not find this to be true. In fact, there was no difference in maximum hunger scores between early time-restricted feeding (eating from 8 a.m. - 2 p.m.) and the control group (eating from 8 a.m. - 8 p.m.).
Although in animal studies time-restricted eating has been associated with increased calorie expenditure, this was not found in humans in this study.
“When meal timing facilitates weight loss, it is likely due to changes in appetite levels, rather than an increase in calories burned. ... Moreover, the improvement in metabolic flexibility and change in fat oxidation patterns may affect other aspects of health, but since this is the first study of early time-restricted feeding in humans, we don't know yet whether these improvements in metabolic flexibility have clinical benefits,” Peterson said. – by Jill Rollet
Peterson C. T-OR-2081. Presented at: ObesityWeek 2016; Oct. 31-Nov. 4, 2016; New Orleans.
Disclosure: Peterson reports no relevant financial disclosures.