Background: Time-restricted eating (TRE), without calorie counting, has become a popular weight loss strategy, yet long-term randomized trials evaluating its efficacy are limited.
Objective: To determine whether TRE is more effective for weight control and cardiometabolic risk reduction compared with calorie restriction (CR) or control.
Design: 12-month randomized controlled trial. (ClinicalTrials.gov: NCT04692532).
Setting: University of Illinois Chicago from January 2021 to September 2022.
Participants: 90 adults with obesity.
Intervention: 8-hour TRE (eating between noon and 8:00 p.m. only, without calorie counting), CR (25% energy restriction daily), or control (eating over a period of 10 or more hours per day). Participants were not blinded.
Measurements: Change in body weight, metabolic markers, and energy intake by month 12.
Results: Seventy-seven persons completed the study. Mean age was 40 years (SD, 11), 33% were Black, and 46% were Hispanic. Mean reduction in energy intake was -425 kcal/d (SD, 531) for TRE and -405 kcal/d (SD, 712) for CR. Compared with the control group, weight loss by month 12 was -4.61 kg (95% CI, -7.37 to -1.85 kg; P ≤ 0.01) (-4.87% [CI, -7.61% to -2.13%]) for the TRE group and -5.42 kg (CI, -9.13 to -1.71 kg; P ≤ 0.01) (-5.30% [CI, -9.06% to -1.54%]) for the CR group, with no statistically significant difference between TRE and CR (0.81 kg [CI, -3.07 to 4.69 kg; P = 0.68]) (0.43% [CI, -3.48% to 4.34%]).
Limitation: Not blinded, not powered to detect relatively large differences in weight loss, and lack of adjustment for multiple comparisons.
Conclusion: Time-restricted eating is more effective in producing weight loss when compared with control but not more effective than CR in a racially diverse population.
Primary funding source: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases.