Time-Restricted Eating in Adults With Metabolic Syndrome : A Randomized Controlled Trial

Abstract

Background: Time-restricted eating (TRE), limiting daily dietary intake to a consistent 8 to 10 hours without mandating calorie reduction, may provide cardiometabolic benefits.

Objective: To determine the effects of TRE as a lifestyle intervention combined with current standard-of-care treatments on cardiometabolic health in adults with metabolic syndrome.

Design: Randomized controlled trial. (ClinicalTrials.gov: NCT04057339).

Setting: Clinical research institute.

Participants: Adults with metabolic syndrome including elevated fasting glucose or hemoglobin A_1c (HbA_1c; pharmacotherapy allowed).

Intervention: Participants were randomly assigned to standard-of-care (SOC) nutritional counseling alone (SOC group) or combined with a personalized 8- to 10-hour TRE intervention (≥4-hour reduction in eating window) (TRE group) for 3 months. Timing of dietary intake was tracked in real time using the myCircadianClock smartphone application.

Measurements: Primary outcomes were HbA_1c, fasting glucose, fasting insulin, homeostasis model assessment of insulin resistance, and glycemic assessments from continuous glucose monitors.

Results: 108 participants from the TIMET study completed the intervention (89% of those randomly assigned; 56 women, mean baseline age, 59 years; body mass index of 31.22 kg/m²; eating window of 14.19 hours). Compared with SOC, TRE improved HbA_1c by -0.10% (95% CI, -0.19% to -0.003%). Statistical outcomes were adjusted for age. There were no major adverse events.

Limitation: Short duration, self-reported diet, potential for multiple elements affecting outcomes.

Conclusion: Personalized 8- to 10-hour TRE is an effective practical lifestyle intervention that modestly improves glycemic regulation and may have broader benefits for cardiometabolic health in adults with metabolic syndrome on top of SOC pharmacotherapy and nutritional counseling.

Primary funding source: National Institutes of Health.

Figure 1.

Timeline of study visits and assessments. CGM = continuous glucose monitor; CV = clinic visit; DXA = dual-energy x-ray absorptiometry; mCC = myCircadianClock.

Figure 2.

CONSORT diagram of participants from screening through completion of the intervention. CONSORT = Consolidated Standards of Reporting Trials; SOC = standard of care; TRE = time-restricted eating.