The Effect of Habitual Sleep Duration on Weight Loss during a Behavioral Weight Loss Intervention in a Mediterranean Population

Abstract

Background: Sleep duration affects metabolic health and regulates appetite, but its role in behavioral weight loss interventions remains unclear as prior studies are limited by small sample sizes, cross-sectional designs, and inconsistent findings.

Objectives: This study aims to examine the associations between nighttime sleep duration and weight loss during a behavioral intervention in adults with overweight or obesity in Spain.

Methods: This secondary analysis included adults with overweight or obesity from the Obesity, Nutrigenetics, Timing, and Mediterranean study, a 25-wk behavioral weight loss program. Participants self-reported sleep duration at enrollment and were categorized as short (<7 h), recommended (7-8 h), or long (>8 h) sleepers. Outcomes included percentage of weight loss, clinically meaningful or successful weight loss (≥5% of initial body weight), rate of weight loss (high/rapid rate ≥0.53 kg/wk), and attrition. Associations were examined using logistic regression and linear mixed-effects models adjusted for age, sex, baseline weight, intervention duration, and clinic site.

Results: Among 3628 participants (mean age 41.2 ± 14.1 y; 77.6% women), 23.7% reported sleeping >8 h, 60.9% reported sleeping 7-8 h, and 15.4% reported sleeping <7 h per night. Long sleepers had significantly lower average weight loss (7.42% of baseline weight) compared with recommended sleepers (7.90%, P = 0.015). Long sleep was associated with 21% lower odds of achieving a weight loss ≥5% of baseline weight [odds ratio (OR): 0.79; 95% confidence interval (CI): 0.66, 0.96], 25% lower odds of rapid weight loss (OR: 0.75; 95% CI: 0.63, 0.89), and 21% higher odds of attrition (OR: 1.21; 95% CI: 1.03, 1.43) compared with recommended sleep. No significant associations were observed for short sleepers. Linear mixed-effects models indicated lower weight loss among long sleepers [β: 0.099; standard error (SE): 0.040; P = 0.015], but not for short sleepers (β: -0.031; SE: 0.048; P = 0.514).

Conclusions: Habitual long sleep duration is associated with reduced weight loss success and increased risk of attrition in a behavioral weight loss intervention. This trial was registered at clinicaltrials.gov as NCT02829619.

Keywords: attrition; behavioral intervention; long sleep; obesity; sleep duration; weight loss.