Time-Restricted Eating Without Calorie Counting for Weight Loss in a Racially Diverse Population : A Randomized Controlled Trial.

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;  ≤ 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;  ≤ 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;  = 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.