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

For nearly 100 years, growth hormone (GH) has been known to affect insulin sensitivity and risk of diabetes. However, the tissue governing the effects of GH signaling on insulin and glucose homeostasis remains unknown. Excess GH reduces fat mass and insulin sensitivity. Conversely, GH insensitivity (GHI) is associated with increased adiposity, augmented insulin sensitivity, and protection from diabetes. Here, we induce adipocyte-specific GHI through conditional deletion of (JAK2A), an obligate transducer of GH signaling. Similar to whole-body GHI, JAK2A mice had increased adiposity and extreme insulin sensitivity. Loss of adipocyte augmented hepatic insulin sensitivity and conferred resistance to diet-induced metabolic stress without overt changes in circulating fatty acids. While GH injections induced hepatic insulin resistance in control mice, the diabetogenic action was absent in JAK2A mice. Adipocyte GH signaling directly impinged on both adipose and hepatic insulin signal transduction. Collectively, our results show that adipose tissue governs the effects of GH on insulin and glucose homeostasis. Further, we show that JAK2 mediates liver insulin sensitivity via an extrahepatic, adipose tissue-dependent mechanism.

Perlecan/Hspg2 (Pln) is a large heparan sulfate proteoglycan abundant in the extracellular matrix of cartilage and the lacuno-canalicular space of adult bones. While Pln function during cartilage development is critical, evidenced by deficiency disorders including Schwartz-Jampel Syndrome and dyssegmental dysplasia Silverman-Handmaker type, little is known about its function in development of bone shape and quality. The purpose of this study was to understand the contribution of Pln to bone geometric and mechanical properties. We used hypomorph mutant mice that secrete negligible amount of Pln into skeletal tissues and analyzed their adult bone properties using micro-computed tomography and three-point-bending tests. Bone shortening and widening in Pln mutants was observed and could be attributed to loss of growth plate organization and accelerated osteogenesis that was reflected by elevated cortical thickness at older ages. This effect was more pronounced in Pln mutant females indicating a gender-specific effect of Pln deficiency on bone geometry. Additionally, mutant females, and to a lesser extent mutant males, increased their elastic modulus and bone mineral densities to counteract changes in bone shape, but at the expense of increased brittleness. In summary, Pln deficiency alters cartilage matrix patterning and, as we now show, coordinately influences bone formation and calcification.

Objective The aim of this study was to determine whether a Mediterranean‐style, ketogenic diet mobile health application (app) with breath acetone biofeedback is superior to a calorie‐restricted, low‐fat diet app in promoting weight loss. Methods Participants (n = 155) with overweight/obesity (mean [SD]: age 41 [11] years, BMI = 34 [5] kg/m2, 71% female) were randomized to one of the interventions delivered entirely via app. Participants received a wireless scale and were instructed to take daily weight measurements. A third‐party laboratory collected blood samples at baseline and 12 weeks. Results Weight loss at 12 weeks was greater in the ketogenic (−5.6 kg; 95% CI: −6.7 kg to −4.5 kg) compared with the low‐fat group (−2.5 kg; 95% CI: −3.6 kg to −1.4 kg) (between‐group difference: −3.1 kg; 95% CI: −4.6 kg to −1.5 kg; p < 0.001). Weight loss at 24 weeks indicated durability of the effect (between‐group difference: −5.5 kg; 95% CI: −8.3 kg to −2.8 kg; p < 0.001). Secondary/exploratory outcomes of hemoglobin A1c and liver enzymes were improved to a greater extent in the ketogenic diet group (p < 0.01). Conclusions Among adults with overweight/obesity, a ketogenic diet app with breath acetone biofeedback was superior to a calorie‐restricted diet app at promoting weight loss in a real‐world setting.

Background Obesity and being overweight are major contributing factors for many diseases. Calorie restricted diets often fail to result in sustained long-term weight loss. Very low–carbohydrate, high-fat ketogenic diets have been suggested to have superior metabolic and weight loss effects. Keyto is a low-cost, highly scalable mobile health (mHealth) app paired with a noninvasive biofeedback tool aimed at facilitating weight loss through a personalized healthy and predominantly plant- and fish-based ketogenic diet. Objective This protocol describes a randomized trial comparing the efficacy of the Keyto mHealth app and device intervention to that of Weight Watchers’ WW app in individuals who are overweight or obese. The primary outcome is weight loss after 12 weeks. Secondary and exploratory outcomes, including metabolic and cardiovascular risk factors, will be assessed at 12, 24, and 48 weeks. Methods A total of 144 participants will be recruited and randomized to either the Keyto program or Weight Watchers program. Study participants will be guided through the study via video conference or phone calls and will undergo a fasting blood analysis performed by a third-party diagnostic lab at weeks 0 and 12 to assess metabolic and cardiovascular risk markers. All participants will be asked to weigh themselves daily on a study-provided Bluetooth-enabled scale. Participants randomized to the Keyto arm will also be asked to measure their breath acetone levels, a measure of ketosis, with the Keyto device 3 times per day. Results Recruitment started in December 2019. Rolling recruitment is expected to be completed by July 2020. Data collection and analysis of the primary intervention phase is expected to be completed in October 2020. The 24- and 48-week follow-ups are expected to be completed in January 2021 and July 2021, respectively. Conclusions This trial will provide high-quality evidence regarding the efficacy of the Keyto weight loss program in individuals who are overweight and obese in a free-living condition. This study also fills a gap by examining the impact of a ketogenic diet emphasizing plant- and fish-based fats on blood lipid profile and cardiovascular disease risk. Trial Registration ClinicalTrials.gov NCT04165707; https://clinicaltrials.gov/ct2/show/NCT04165707. International Registered Report Identifier (IRRID) DERR1-10.2196/19053

Background Low-carbohydrate ketogenic diets are a viable method to lose weight that have regained popularity in recent years. Technology in the form of mobile health (mHealth) apps allows for scalable and remote delivery of such dietary interventions and are increasingly being used by the general population without direct medical supervision. However, it is currently unknown which factors related to app use and user behavior are associated with successful weight loss. Objective First, to describe and characterize user behavior, we aim to examine characteristics and user behaviors over time of participants who were enrolled in a remotely delivered clinical weight loss trial that tested an mHealth ketogenic diet app paired with a breath acetone biofeedback device. Second, to identify variables of importance to weight loss at 12 weeks that may offer insight for future development of dietary mHealth interventions, we aim to explore which app- and adherence-related user behaviors characterized successful weight loss. Methods We analyzed app use and self-reported questionnaire data from 75 adults with overweight or obesity who participated in the intervention arm of a previous weight loss study. We examined data patterns over time through linear mixed models and performed correlation, linear regression, and causal mediation analyses to characterize diet-, weight-, and app-related user behavior associated with weight loss. Results In the context of a low-carbohydrate ketogenic diet intervention delivered remotely through an mHealth app paired with a breath acetone biofeedback device, self-reported dietary adherence seemed to be the most important factor to predict weight loss (β=–.31; t54=–2.366; P=.02). Furthermore, self-reported adherence mediated the relationship between greater app engagement (from c=–0.008, 95% CI –0.014 to –0.0019 to c’=–0.0035, 95% CI –0.0094 to 0.0024) or higher breath acetone levels (from c=–1.34, 95% CI –2.28 to –0.40 to c’=–0.40, 95% CI –1.42 to 0.62) and greater weight loss, explaining a total of 27.8% and 28.8% of the variance in weight loss, respectively. User behavior (compliance with weight measurements and app engagement) and adherence-related aspects (breath acetone values and self-reported dietary adherence) over time differed between individuals who achieved a clinically significant weight loss of >5% and those who did not. Conclusions Our in-depth examination of app- and adherence-related user behaviors offers insight into factors associated with successful weight loss in the context of mHealth interventions. In particular, our finding that self-reported dietary adherence was the most important metric predicting weight loss may aid in the development of future mHealth dietary interventions. Trial Registration ClinicalTrials.gov NCT04165707; https://clinicaltrials.gov/ct2/show/NCT04165707 International Registered Report Identifier (IRRID) RR2-10.2196/19053

Background Visceral adiposity, more so than overall adiposity, is associated with chronic disease and mortality. There has been, to our knowledge, little research exploring the association between diet quality and visceral adipose tissue (VAT) among a mulitethnic population aged 18–80 y. Objective The primary objective of this cross-sectional analysis was to examine the association between diet quality [Healthy Eating Index–2010 (HEI-2010) scores] and VAT among a multiethnic population of young, middle, and older aged adults in the United States. Secondary objectives were to repeat these analyses with overall adiposity and blood-based biomarkers for type 2 diabetes and cardiovascular disease risk as outcome measures. Methods A total of 540 adults (dropped out: n = 4; age: 18–40 y, n = 220; 40–60 y, n = 183; 60–80 y, n = 133) were recruited across 3 sites (Honolulu County, San Francisco, and Baton Rouge) for the Shape Up! Adults study. Whole-body DXA, anthropometry, fasting blood draw, and questionnaires (food frequency, physical activity, and demographic characteristics) were completed. Linear regression was used to assess the associations between HEI-2010 tertiles and VAT and secondary outcome measures among all participants and age-specific strata, while adjusting for known confounders. Results VAT, BMI (kg/m2), body fat percentage, total body fat, trunk fat, insulin, and insulin resistance were inversely related to diet quality (all P values &lt; 0.004). When stratified by age, diet quality was inversely associated with VAT among participants aged 60–80 y (P &lt; 0.006) and VAT/subcutaneous adipose tissue (SAT) among participants aged 40–60 y (P &lt; 0.008). Conclusions Higher-quality diet was associated with lower VAT, overall adiposity, and insulin resistance among this multiethnic population of young, middle, and older aged adults with ages ranging from 18 to 80 y. More specifically, adherence to a high-quality diet may minimize VAT accumulation in adults aged 60–80 y and preferentially promote storage of SAT compared with VAT in adults aged 40–60 y. This study was registered at clinicaltrials.gov as NCT03637855.

For nearly 100 years, Growth Hormone (GH) has been known to regulate insulin sensitivity and risk of diabetes. However, the tissue governing the effects of GH signaling on insulin and glucose homeostasis remains unknown. Excess GH reduces fat mass and insulin sensitivity. Conversely, GH insensitivity (GHI) is associated with increased adiposity, augmented insulin sensitivity, and protection from diabetes.Here we induce adipocyte-specific GHI through conditional deletion of Jak2 (JAK2A), an obligate transducer of GH signaling. Similar to whole-body GHI, JAK2A mice had increased adiposity and extreme insulin sensitivity. Loss of adipocyte Jak2 augmented hepatic insulin sensitivity and conferred resistance to diet-induced metabolic stress without overt changes in circulating fatty acids. While GH injections induced hepatic insulin resistance in control mice, the diabetogenic action was absent in JAK2A mice. Collectively, our results show that adipose tissue governs the effects of GH on insulin and glucose homeostasis. Further, we show that JAK2 mediates liver insulin sensitivity via an extra-hepatic, adipose tissue-dependent mechanism.