IMPORTANCEThe efficacy and safety of time-restricted eating have not been explored in large randomized clinical trials.OBJECTIVE To determine the effect of 16:8-hour time-restricted eating on weight loss and metabolic risk markers. INTERVENTIONSParticipants were randomized such that the consistent meal timing (CMT) group was instructed to eat 3 structured meals per day, and the time-restricted eating (TRE) group was instructed to eat ad libitum from 12:00 PM until 8:00 PM and completely abstain from caloric intake from 8:00 PM until 12:00 PM the following day. DESIGN, SETTING, AND PARTICIPANTSThis 12-week randomized clinical trial including men and women aged 18 to 64 years with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) of 27 to 43 was conducted on a custom mobile study application. Participants received a Bluetooth scale. Participants lived anywhere in the United States, with a subset of 50 participants living near San Francisco, California, who underwent in-person testing. MAIN OUTCOMES AND MEASURESThe primary outcome was weight loss. Secondary outcomes from the in-person cohort included changes in weight, fat mass, lean mass, fasting insulin, fasting glucose, hemoglobin A 1c levels, estimated energy intake, total energy expenditure, and resting energy expenditure.RESULTS Overall, 116 participants (mean [SD] age, 46.5 [10.5] years; 70 [60.3%] men) were included in the study. There was a significant decrease in weight in the TRE (−0.94 kg; 95% CI, −1.68 to −0.20; P = .01), but no significant change in the CMT group (−0.68 kg; 95% CI, -1.41 to 0.05, P = .07) or between groups (−0.26 kg; 95% CI, −1.30 to 0.78; P = .63). In the in-person cohort (n = 25 TRE, n = 25 CMT), there was a significant within-group decrease in weight in the TRE group (−1.70 kg; 95% CI, −2.56 to −0.83; P < .001). There was also a significant difference in appendicular lean mass index between groups (−0.16 kg/m 2 ; 95% CI, −0.27 to −0.05; P = .005). There were no significant changes in any of the other secondary outcomes within or between groups. There were no differences in estimated energy intake between groups.CONCLUSIONS AND RELEVANCE Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day.TRIAL REGISTRATION ClinicalTrials.gov Identifiers: NCT03393195 and NCT03637855

BACKGROUND Consumer devices with broad reach may be useful in screening for atrial fibrillation (AF) in appropriate populations. However, currently no consumer devices are capable of continuous monitoring for AF.OBJECTIVE The purpose of this study was to estimate the sensitivity and specificity of a smartwatch algorithm for continuous detection of AF from sinus rhythm in a free-living setting.METHODS We studied a commercially available smartwatch with photoplethysmography (W-PPG) and electrocardiogram (W-ECG) capabilities. We validated a novel W-PPG algorithm combined with a W-ECG algorithm in a free-living setting, and compared the results to those of a 28-day continuous ECG patch (P-ECG).RESULTS A total of 204 participants completed the free-living study, recording 81,944 hours with both P-ECG and smartwatch measurements. We found sensitivity of 87.8% (95% confidence interval [CI] 83.6%-91.0%) and specificity of 97.4% (95% CI 97.1%-97.7%) for the W-PPG algorithm (every 5-minute classification); sensitivity of 98.9% (95% CI 98.1%-99.4%) and specificity of 99.3% (95% CI 99.1%-99.5%) for the W-ECG algorithm; and sensitivity of 96.9% (95% CI 93.7%-98.5%) and specificity of 99.3% (95% CI 98.4%-99.7%) for W-PPG triggered W-ECG with a single W-ECG required for confirmation of AF. We found a very strong correlation of W-PPG in quantifying AF burden compared to P-ECG (r 5 0.98).CONCLUSION Our findings demonstrate that a novel algorithm using a commercially available smartwatch can continuously detect AF with excellent performance and that confirmation with W-ECG further enhances specificity. In addition, our W-PPG algorithm can estimate AF burden. Further research is needed to determine whether this algorithm is useful in screening for AF in select atrisk patients.

Background: Studies indicate that time-restricted eating (TRE) can prevent weight gain and/or lead to weight loss [1,2]. The few human studies to date are small and/or non-randomized [3,4]. This is a prospective and randomized study in humans who are overweight and obese designed to determine if TRE leads to weight loss and to characterize the metabolic effects of TRE. Methods: 140 overweight and obese males and females with a body mass index between 27-43 kg/m2 were enrolled in the study. 100 participants completed the 12-week protocol. The study was conducted on a custom mobile study app on the Eureka Research Platform. Participants were given a Bluetooth weight scale to use daily, which was connected through the study app. Subjects were randomized to one of two eating plans and received daily reminders about their eating windows through the app. The control group was instructed to eat three structured meals per day. The TRE group was instructed to eat ad libitum from 12:00 pm until 8:00 pm and completely abstain from caloric intake from 8:00 pm until 12:00 pm the following day (16h fast:8h eat). Participants who lived within 60 miles of the study site were eligible to undergo extensive in-person metabolic testing. Results: Weight change in the TRE group was -1.3 kg compared to -0.6 kg in the control group (p=0.22). 46 (TRE n=22; control=24) of 50 participants who opted into the “in-person” visits completed all 4 visits. In that cohort, weight change in the TRE group was -1.62 kg compared to -0.57 kg in control (p=0.09). There were no significant differences in the changes in total fat mass, visceral or subcutaneous fat mass, waist or hip measurements, or resting metabolic rate. However, there was a trend towards reduced fat-free mass in the TRE group (-1.10kg) compared to controls (-0.35kg) (p=0.09). There was a significant change in the appendicular fat-free mass index of the TRE subjects compared to controls (p=0.011). This change in appendicular fat-free mass index was not associated with significant differences in strength measures. No changes were observed in plasma ketones, insulin, or glucose between treatment groups. Conclusion: These results indicate that TRE may lead to reductions in body weight in individuals who are overweight or obese. However, the majority of weight loss is attributed to reductions in fat-free mass rather than fat mass. Future analyses will determine if TRE leads to changes in metabolic blood markers or the plasma metabolome. References: 1.Hatori et al. Cell Metab. 2012 Jun 6;15(6):848-60. doi: 10.1016/j.cmet.2012.04.019. Epub 2012 May 17.2. Chaix et al. Cell Metab. 2019 Feb 5;29(2):303-319.e4. doi: 10.1016/j.cmet.2018.08.004. Epub 2018 Aug 30.3.Moro et al. J Transl Med. 2016 Oct 13;14(1):290.4.Wilkinson et al.Cell Metab. 2020 Jan 7;31(1):92-104.e5. doi: 10.1016/j.cmet.2019.11.004. Epub 2019 Dec 5.