The mean age of 12 study participants was 26 years; five were females. Their mean body mass index was 21.9 kg/m2. Dr. Goel reported that participants had excellent adherence to assigned eating schedules, with no differences between the conditions. Weight was decreased on the daytime vs. delayed eating schedule. Specifically, Cohen’s d effect sizes were 0.57 overall: 1.16 for females and 0.33 for males, all in the small to large range. Resting energy expenditure, respiratory quotient, and trunk fat percentage/leg fat percentage were decreased on the daytime vs. delayed eating condition, with Cohen’s d effect sizes of 0.45-1.02, all in the medium to large range. In addition, total cholesterol and insulin were decreased on the daytime eating condition (medium effect sizes of 0.60 and 0.57, respectively), while triglycerides and glucose were increased on the delayed condition (medium effect sizes of 0.46 and 0.52, respectively).
Weight, adiposity, energy metabolism, and hormonal measures did not differ significantly between the pre-daytime and pre-delayed eating conditions, suggesting that they returned to pre-condition levels after the washout period.
“One of the things we’re advocating is that with consistent daytime eating, you can lose weight and/or remain at weight maintenance,” Dr. Goel said. “Consistency is very important. Across 8 weeks, you’re becoming metabolically healthier because you’re not eating that late-night meal or snack. We had shown in previous sleep loss studies that people were eating 500 calories late in the evening on consecutive nights and gaining a substantial amount of weight.”
She and her colleagues are currently enrolling obese individuals into a similarly designed trial, “where we expect much bigger changes metabolically,” she said. The study was funded by a grant from the National Institutes of Health. Dr. Goel reported having no financial disclosures.
SOURCE: Goel N et al. .