Cardiorespiratory Fitness as a Predictor of Non-Cardiovascular Disease and Non-Cancer Mortality in Men.

OBJECTIVE: To evaluate the association of 5 major cause-specific non-cardiovascular disease (CVD) and non-cancer deaths with cardiorespiratory fitness (CRF). METHODS: Patients were 36,645 men (43.3±9.3 years) free of known CVD and cancer at baseline who completed a maximal treadmill graded exercise test during a preventive examination at the Cooper Clinic (Dallas, Texas) between 1971 and 2003. CRF was quantified as maximal treadmill exercise test duration and grouped as low (referent), moderate, and high. Cause-specific non-CVD non-cancer deaths were (1) diabetes or kidney disease, (2) chronic respiratory disease, (3) acute respiratory and infectious disease, (4) injuries, and (5) other non-CVD non-cancer deaths. RESULTS: A total of 694 non-CVD non-cancer deaths occurred during an average of 17 years of follow-up. After adjustment for covariates, hazard ratios (95% confidence intervals) for moderate and high CRF, respectively, were 0.57 (0.47 to 0.69) and 0.43 (0.34 to 0.54) for overall non-CVD non-cancer deaths (P<.0001); 0.39 (0.28 to 0.54) and 0.17 (0.10 to 0.28) for diabetes or kidney disease (P<.001); 0.36 (0.22 to 0.59) and 0.09 (0.04 to 0.20) for chronic respiratory diseases (P<.001 for all); 0.74 (0.47 to 1.16) and 0.34 (0.19 to 0.61) for acute respiratory and infectious diseases (P<.01 for both); and 0.48 (0.35 to 0.66) and 0.38 (0.26 to 0.55) for any other non-CVD non-cancer deaths (P<.0001 for both). CONCLUSION: Higher levels of CRF were significantly associated with lower risk of mortality from the 5 major non-CVD non-cancer causes. These results suggest that improvement in CRF may reduce non-CVD non-cancer deaths, which account for a significant proportion of adult mortality.

Influence of Food Security Status and Diet Quality on Maternal Gestational Weight Gain.

BACKGROUND: Recommended gestational weight gain (GWG) is crucial for health of women and their offspring. Food security status is hypothesized to influence diet quality and GWG. Therefore, we examined the relationship between diet quality and GWG by food security status. METHODS: Participants (n = 679) were enrolled in the Initial Vanguard Study of the National Children's Study. GWG was calculated as third trimester weight minus prepregnancy weight. Food security status and diet quality (Healthy Eating Index [HEI]-2015) were assessed using the Household Food Security Survey and a Diet History Questionnaire, respectively. General linear models evaluated the relationship between GWG and HEI-2015 by food security status. RESULTS: A greater proportion of women experienced food security (81.3%) compared with food insecurity (18.7%). In women with food security, GWG was negatively associated with HEI-2015 in women having overweight (r = -0.421, P = .003) and positively associated with HEI-2015 in women with inadequate GWG (r = 0.224, P = .019). Conversely, no significant relationships were found between GWG and HEI-2015 in women with food insecurity. DISCUSSION: Improved diet quality potentially lowers GWG in women with food security. However, in vulnerable populations, including women with food insecurity, improvements in diet quality may not effectively enhance GWG.

Healthful Eating Behaviors among Couples Contribute to Lower Gestational Weight Gain.

Through longitudinal analysis from the GLOWING cohort study, we examined the independent and joint relationships between couples' eating behaviors and gestational weight gain (GWG). Pregnant persons (n = 218) and their non-pregnant partners (n = 157) completed an Eating Inventory. GWG was calculated as gestation weight at 36 weeks minus that at 10 weeks. General linear models were used to examine the relationships between GWG and the pregnant persons, non-pregnant partners, and couples (n = 137; mean of pregnant persons and non-pregnant partners) cognitive restraint (range 0-21), dietary disinhibition (range 0-18), and perceived hunger (range 0-14), with higher scores reflecting poorer eating behaviors. The adjusted models included race/ethnicity, education, income, marital status, and age. The pregnant persons and their non-pregnant partners' cognitive restraint, dietary disinhibition, and perceived hunger scores were 9.8 ± 4.7, 4.8 ± 3.2, and 4.4 ± 2.5 and 6.6 ± 4.6, 5.4 ± 3.4, and 4.7 ± 3.2, respectively. Higher cognitive restraint scores among the pregnant persons and couples were positively associated with GWG (p ≤ 0.04 for both). Stratified analyses revealed this was significant for the pregnant persons with overweight (p ≤ 0.04). The non-pregnant partners' eating behaviors alone were not significantly associated with GWG (p ≥ 0.31 for all). The other explored relationships between GWG and the couples' eating behaviors were insignificant (p ≥ 0.12 for all). Among the pregnant persons and couples, reduced GWG may be achieved with higher levels of restrained eating. Involving non-pregnant partners in programs to optimize GWG may be beneficial.

Effect of Exercise Training on Lipoprotein Subclass Particle Concentrations and Sizes in Older Women: Results from a Randomized Controlled Trial.

BACKGROUND: Evidence suggests that lipoprotein subclass particles are critical markers of cardiovascular disease (CVD) risk. Older women have increased CVD risk related to age. The purpose of this study was to determine whether low and moderate doses of exercise influence lipoprotein subclasses. METHODS: Women (60-75 years) were randomized into groups for 16 weeks of moderate-intensity exercise training at a low or moderate dose (33.6 and 58.8 kJ/kg body weight weekly, respectively). Lipoprotein subclasses were determined by nuclear magnetic resonance spectroscopy before and after the training. RESULTS: The average weekly exercise duration was 109 and 164 min, for low- and moderate-dose groups, respectively. In the low-dose group, high-density lipoprotein particle (HDL-P) concentration decreased (Δ = -1.9 ± 3.1 µmol/L, mean ± SD, p = 0.002) and mean HDL-P size increased (Δ = 0.1 ± 0.3 nm, p = 0.028). In the moderate-dose group, mean HDL-P size (Δ = 0.1 ± 0.2 nm; p = 0.024) and low-density lipoprotein particle size increased (Δ = 0.4 ± 3.9 nm; p = 0.007). Baseline body mass index, peak oxygen consumption and age were associated with changes in a few lipoprotein subclasses. CONCLUSIONS: In this sample of inactive older women, moderate-intensity exercise training at a dose equivalent to or even lower than the minimally recommended level by public health agencies induced changes in lipoprotein subclasses in line with reduced CVD risk. However, higher doses are encouraged for greater health benefits.

Access, Interest, and Barriers to Incorporation of Birth Doula Care in the United States.

Doula care improves maternal care, yet barriers exist to incorporating doula care. The purpose of this study was to evaluate interest and barriers to doula care. Overall, 508 women, 26-35 years of age (54.5%), White/Caucasian (89.8%), and married (88.6%), completed this study. Most reported ≥1 previous birth (97.6%). Respondents would "feel comfortable" (73.2%) and "more confident" (54.9%) with doula care at birth, and 57.9% reported their provider would be supportive of doula care. Only 39.0% expressed benefits to doula care during pregnancy compared to 72.6% at birth and 68.1% during postpartum. Most would hire a doula if health insurance covered some of the costs. Despite the recognized benefits and support of doula care, cost-associated barriers exist to the incorporation of doula care.

Body weight and fat trajectories of Black and White women in the first postpartum year.

OBJECTIVE: The aim of this study was to examine changes in body weight and fat in Black and White women during the first postpartum year and to determine whether there is preferential retention of fat mass and abdominal fat. METHODS: Body composition was quantified by dual-energy x-ray absorptiometry in Black (n = 49) and White (n = 85) women at 6 to 8 weeks, 6 months, and 12 months after delivery of a singleton infant. RESULTS: Weight, fat mass, percent body fat, and fat in the trunk, android, gynoid, and limb regions decreased from 6 to 8 weeks to 12 months in White women, but not in Black women (fat mass, adjusted mean [SE]: 29.6 [1.3] to 26.9 [1.3] kg in White women and 34.5 [1.5] to 36.8 [1.8] kg in Black women). In the entire sample, fat mass was higher at 6 months than at 6 to 8 weeks, independent of weight change; visceral fat was higher at 12 months (686 [45] g) than at 6 to 8 weeks (611 [42] g) and 6 months (626 [43] g); and android fat was higher at 12 months than at 6 months, independent of fat change. CONCLUSIONS: Black women were less likely than White women to lose weight and fat in the postpartum period. There was preferential retention of fat in the abdominal area.

Associations between Sleep and Body Composition in Older Women and the Potential Role of Physical Function.

Purpose: The relationship between sleep and adiposity in older women remains unclear partly due to the reliance of body mass index as a measure of adiposity. The purpose of this study was to investigate associations between objectively measured sleep characteristics and body composition measured by dual energy x-ray absorptiometry (DXA) in older women. A secondary purpose was to examine if physical function mediates this relationship. Methods: Non-obese older women (ages 60-75 years, n=102) were included in the study. Total sleep time (TST), time in bed (TIB), sleep efficiency (SE), and wake after sleep onset (WASO) were determined by actigraphy. A battery of tests was used to assess physical function. Results: With adjustment for age, there was a negative association between TST and TIB with lean mass. Both grip strength and dominant leg extension were associated with TST, TIB, and lean mass; the associations between TST and TIB with lean mass were lost after adjusting for grip strength or leg extension strength. Additionally, SE was negatively associated with total, gynoid, and trunk lean mass, and there was a positive association between TST and percent trunk fat, and WASO and gynoid lean mass, with age adjusted. Conclusions: Sleep characteristics, TST, TIB, SE, and WASO, were associated body composition measures in this sample of older women. The relationship between TST and TIB with body composition was mediated, in part, by grip strength and leg extension strength.

Understanding Barriers and Facilitators to Physical Activity Engagement to Inform a Precision Prescription Approach during Pregnancy.

Physical activity during pregnancy is an important health behavior. However, many pregnant individuals are provided with little-to-no guidance to adequately engage in physical activity. The purpose of this quantitative and quasi-qualitative study of currently or previously pregnant women was to examine physical activity behaviors in pregnancy and understand barriers and facilitators to achieving physical activity recommendations. Overall, 431 women (18+ years), White/Caucasian (84.5%), married (84.9%), and currently pregnant (66.6%), completed an online survey study. Most women (69.4%) reported engaging in cardio-based physical activity and willing to engage in physical activity to meet guidelines between 2 and 5 days per week (77.4 -88.8%). The most frequently reported barriers were feeling too tired (72.8%) or uncomfortable (71.8%) and childcare needs (57.8%). Being able to choose time of day (96.0%), accessing home workouts (92.9%), and having a personalized prescription (95.6%) were the most reported facilitators. Open comment feedback resulted in additional barriers, such as ensuring proper energy intake, while motivation and support from other pregnant individuals were fundamental facilitators. Individualized physical activity prescription is lacking in routine prenatal care. To support pregnant individuals to achieve physical activity recommendations, developing a prescription with suitable modalities, at-home options, and consideration for physical activity timing are required.

Cross-Sectional and Individual Relationships between Physical Activity and Glycemic Variability.

Introduction/Purpose: Overweight or obese adults spend more time sedentary and less time performing physical activity (PA) and are at an increased risk for developing impaired glycemic health. Free-living environments may provide insight into glycemic health in addition to clinical assessments. The purpose of this study was to examine the relationship between PA and glycemic health assessed by continuous glucose monitoring (CGM). Methods: Twenty-eight overweight or obese adults each wore an accelerometer and CGM over the same 7 consecutive days. Average daily time (minutes and metabolic-equivalent minutes (MET-minutes)) and associated energy expenditure performing light (LPA), moderate-to-vigorous (MVPA), total PA, and standard deviation (SD) across days were calculated. Average daily 24-h and waking glycemia, mean glucose concentration, glycemic variability measured as the continuous overlapping net glycemic action, mean amplitude of glycemic excursions, and mean of daily difference were assessed. Results: LPA MET-minutes per day was positively associated with 24-h and waking glycemia time-in-range and negatively associated with 24-h and waking time in hyperglycemia. Total PA time and the SD of MVPA and total PA time were negatively associated with 24-h mean glucose concentration. Individual-level analysis identified that most participants (50%-71%) expressed negative associations between LPA and MVPA time with 24-h mean glucose concentration, mean amplitude of glycemic excursion, and 4-h continuous overlapping net glycemic action. Conclusions: Expectedly, greater total PA time and intensity-specific PA time were associated with lower 24-h and waking mean glucose concentration, greater glycemia time-in-range, and less time in hyperglycemia. The relationship between glucose concentrations and PA time SD was unexpected, whereas most participants expressed hypothesized relationships, which necessitates further exploration.

Lifestyle interventions in pregnancy targeting GDM prevention: looking ahead to precision medicine.

Gestational diabetes mellitus (GDM) is the most prevalent pregnancy-related endocrinopathy, affecting up to 25% of pregnancies worldwide. Pregnant individuals who develop GDM have an increased risk of complications during pregnancy and birth, as well as future development of type 2 diabetes mellitus and CVD. This increased risk is subsequently passed along to the offspring, perpetuating a cycle of metabolic dysfunction across generations. GDM prevention strategies have had mixed results for many years, but more recent systematic reviews and meta-analyses have suggested potential new avenues of prevention. The objective of this review is to summarise the literature examining the efficacy of lifestyle interventions for the prevention of GDM and to uncover if specific individual-level characteristics influence this outcome. Based on the present literature, we determined that future trials should be designed to understand if initiation of lifestyle intervention in the preconception period is more effective to reduce GDM. Furthermore, trials initiated during pregnancy should be developed through the lens of precision prevention. That is, trials should tailor intervention approaches based on individual-level risk defined by the presence of modifiable and non-modifiable risk factors. Finally, future interventions might also benefit from just-in-time adaptive intervention designs, which allow for interventions to be modified in real-time based on objective assessments of an individual's response.

Assessment of Eating Behaviors and Perceptions of Time-Restricted Eating During Pregnancy.

BACKGROUND: The maternal metabolic milieu is challenged during pregnancy and may result in unwarranted metabolic complications. A time-restricted eating (TRE) pattern may optimize the metabolic response to pregnancy by improving glucose metabolism and reducing circulating glucose concentrations, as it does in nonpregnant individuals. OBJECTIVES: The objectives of this study were to 1) assess eating timing in pregnant women; 2) understand the perceptions of adopting a TRE pattern; 3) determine the barriers and support mechanisms for incorporating a TRE pattern; and 4) identify those most willing to adopt a TRE pattern during pregnancy. METHODS: This was a cross-sectional quantitative and quasi-qualitative online survey study for women who were pregnant at the time of study completion or had given birth in the prior 2 years. Group analyses were performed based off willingness to try a TRE pattern using chi-squared analyses, independent samples t-tests, or an analysis of variance. Three separate reviewers reviewed qualitative responses. RESULTS: A total of 431 women (BMI, 27.5 ± 0.3 kg/m2) completed the study. Of the participating women, 23.7% reported willingness to try a TRE pattern during pregnancy. Top barriers to adopting a TRE pattern during pregnancy were concerns for 1) safety; 2) nausea; and 3) hunger. The highest ranked support mechanisms were: 1) the ability to choose the eating window; 2) more frequent prenatal visits to ensure the health of the baby; and 3) receiving feedback from a dietician/nutritionist. Women who did not identify as White/Caucasian expressed a higher willingness to try a TRE pattern during pregnancy (P = 0.01). Women who were nulliparous expressed a higher willingness to try a TRE pattern (P = 0.05). DISCUSSION: TRE, an alternative dietary strategy shown to optimize metabolic control, may be effective to prevent and manage pregnancy-related metabolic impairments. To create an effective TRE intervention during pregnancy, the input of pregnant mothers is necessary to increase adherence and acceptability.

Impact of COVID-19 Stay-at-Home Orders on Health Behaviors and Anxiety in Black and White Americans.

BACKGROUND: In the United States (US), the incidence and severity of COVID-19 infections, hospitalizations, and deaths are higher in Black compared to White residents. Systemic inequities and differences in health behaviors may contribute to disparities in COVID-19 health outcomes. The aim of this study was to examine the impact of COVID-19 stay-at-home orders on changes in health behaviors and anxiety in Black and White adults residing in the US. METHODS: Beginning April 2020, the Pennington Biomedical Research Center COVID-19 Health Behaviors Study collected information on changes to employment, income, diet, physical activity, anxiety, and sleep patterns through a global online survey. RESULTS: Of 4542 survey respondents in the US, 7% identified as Black and 93% as White. Prior to the COVID-19 stay-at-home orders, a greater proportion of Blacks compared to Whites reported earning < US$50,000 per year (p < 0.0001). A greater proportion of Blacks reported being laid off, working fewer hours, and working from home following COVID-19 stay-at-home orders (p < 0.0001 for all). In the overall sample, eating behaviors improved, physical activity decreased, sleep time prolonged, and anxiety heightened following COVID-19 stay-at-home orders (p < 0.01 for all), which were universal between Black and White respondents (p ≥ 0.315 for all). CONCLUSIONS: This study highlights the disproportionate changes to employment and income in Blacks, with no differential impact on health behaviors and anxiety compared to Whites due to COVID-19 stay-at-home orders. As the COVID-19 pandemic continues, disproportionate changes to employment and income status may widen among Blacks and Whites, which may influence health behaviors and anxiety.

Eating Behaviors and Dietary Patterns of Women during Pregnancy: Optimizing the Universal 'Teachable Moment'.

Understanding women's perceptions of eating behaviors and dietary patterns can inform the 'teachable moment' model of pregnancy. Our objectives were to describe eating behaviors and dietary patterns in pregnancy. This was a cross-sectional, national electronic survey. Women were ≥18 years of age, living in the United States, currently pregnant or less than two years postpartum, and had internet access. Age, education, race, and marriage were included as covariates in ordinal and binary logistic regressions (significance p < 0.05). Women (n = 587 eligible) made positive or negative changes to their diets, while others maintained pre-existing eating behaviors. The majority of women did not try (84.9 to 95.1% across diets) and were unwilling to try (66.6 to 81%) specific dietary patterns during pregnancy. Concerns included not eating a balanced diet (60.1 to 65.9%), difficulty in implementation without family (63.2 to 64.8%), and expense (58.7 to 60.1%). Helpful strategies included being provided all meals and snacks (88.1 to 90.6%) and periodic consultations with a dietitian or nutritionist (85 to 86.7%). Responses differed across subgroups of parity, body mass index, and trimester, notably in women with obesity who reported healthier changes to their diet (p < 0.05). Our study underscores the importance of tailoring care early to individual needs, characteristics, and circumstances.

Beyond weight loss: current perspectives on the impact of calorie restriction on healthspan and lifespan.

Introduction: Changes to mental, physical, and physiological functions drive the complex processes underlying the variable progression of human aging. Nutritional interventions are one of the most promising non-pharmacological therapeutics to attenuate aging in humans. This narrative review aims to describe the implications of moderate and prolonged calorie restriction (CR) in healthy adults without obesity that occur beyond weight loss.Areas covered: Findings from CR studies, such as the CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) trials, the most rigorous trials to date examining a prolonged 25% CR, are described. The main areas covered include; changes to anthropometrics, energy metabolism, cardiometabolic health, inflammation and immune function, physical fitness, health behaviors, and mental health in response to weight loss (1-year) and weight loss maintenance (2-year).Expert opinion: CR presents a novel and effective therapeutic approach for improving healthspan and biomarkers of lifespan. To date, scientific evidence suggests that continued CR, under medical supervision, is accompanied with persistent and beneficial effects on health outcomes independent of weight loss. Mechanisms are yet to be fully elucidated, and novel dietary approaches that may similarly attenuate aging-related conditions should be explored and compared to traditional CR.

Alterations in Glycemic Variability, Vascular Health, and Oxidative Stress following a 12-Week Aerobic Exercise Intervention-A Pilot Study.

The state of being overweight or obese leads to an increased risk of development of cardiometabolic disease. Increases in glycemic variability have been associated with greater induction of oxidative stress and declined vascular health, which may be exacerbated by higher weight status and improved through exercise. The purpose of this study was to examine the impact of a twelve-week aerobic exercise intervention on continuous glucose monitor (CGM) assessed glucose concentrations and glycemic variability, and biomarkers of vascular health and oxidative stress in overweight or obese adults. Eight adults (Age = 48.9 ± 5.2 years; BMI = 29.4 ± 8.3 kg/m2) completed a twelve-week aerobic exercise intervention. Participants walked three times per week at moderate intensity for ~150 minutes each week. All participants wore a CGM for seven consecutive days at baseline and post-intervention. On the final day of monitoring, a fasting blood sample was collected, and an oral glucose tolerance test (OGTT) was performed. Intra- and inter-day glycemic variability was assessed as the mean amplitude of glycemic excursions, continuous overlapping net glycemic action of one-, two-, and four-hour, and the mean observation of daily differences. Plasma concentrations of nitric oxide (NO) and myeloperoxidase (MPO) were measured, and their ratio was calculated (NO:MPO). No CGM-assessed glucose concentrations or measures of glycemic variability changed from baseline to post-intervention. MPO concentration decreased (24.8 ± 8.2 ng/mL to 16.4 ± 4.6 ng/mL, p < 0.01), the NO:MPO ratio improved (3.5:1 to 6.4:1, p < 0.01) following the twelve-week intervention. Individual level changes in body weight and V̇O2peak were found. In conclusion, twelve weeks of aerobic exercise reduced oxidative stress and improved the propensity to vasodilate but did not alter CGM-assessed glucose concentrations or glycemic variability in this group of overweight or obese non-diabetic adults. These findings may be due to individual changes in body weight or V̇O2peak, which necessitates further research to explore their influence on these outcomes of interest.

Glycemic variability: Importance, relationship with physical activity, and the influence of exercise.

Glycemic variability is a more sensitive assessment of glycemic health as opposed to traditional clinical measurements. It considers all blood glucose concentrations over a given period to better account for glucose oscillations that occur and provides clinicians with insight into how individuals regulate and/or maintain their glycemic health. The advancement of continuous glucose monitoring (CGM) allows for the measurement of free-living glucose concentrations while providing a more reliable assessment of treatment of dysregulated glycemic. CGM coupled with management of lifestyle behavioral factors, such as reduced sedentary behavior and increased physical activity and regular exercise, potentially offers a previously untapped method for promoting improved glycemic health through greater regulation of glucose concentrations. The aim of this review is to critically evaluate the evidence regarding the measurement of glycemic variability and summarize the current understanding of the relationship between glycemic variability, sedentary behavior, physical activity, the influence of a single exercise session or repeated exercise sessions, and exercise training. This review considers information pertaining to the strengths and limitations for measuring glycemic variability and provides insight into future study designs aimed at evaluating the relationship between sedentary behavior and physical activity with, as well as the influence of exercise on, glycemic variability as a primary outcome.

Sedentary Time and Physical Activity in Older Women Undergoing Exercise Training.

Older adults have low rates meeting the physical activity (PA) guidelines and high sedentary time. Low PA and excessive sedentary time have been linked to adverse health outcomes. Less is known about whether exercise training influences sedentary time and PA in various intensities. PURPOSE: This study aimed to examine the effects of a 16-wk aerobic exercise training on time spent being sedentary and on light-intensity PA (LPA) and moderate- to vigorous-intensity PA (MVPA) and step numbers in older women. METHODS: Inactive women (n = 61; age = 65.5 ± 4.3 yr) participated in moderate-intensity walking of either a low or a moderate dose (33.6 and 58.8 kJ·kg body weight per week, respectively). They wore a SenseWear Mini Armband at baseline and at end intervention to determine sedentary, LPA, and MVPA time and step numbers. RESULTS: Time being sedentary, or spent on LPA and MVPA, did not change differently by exercise groups with different doses (all P values for group-time interaction >0.580). Overall, time being sedentary reduced from baseline to end intervention by approximately 39 min·d (P < 0.001), and LPA increased by 19 min·d (P = 0.003). MVPA time increased (P < 0.001), which was primarily accounted for by the supervised exercise. Interestingly, daily steps increased more in the moderate-dose than the low-dose group (P = 0.023 for group-time interaction; 33.6% and 19.8% median increase in moderate- and low-dose groups, respectively). Also, there were individual differences in these changes. CONCLUSION: Results indicated that, on average, older women did not reduce time of LPA or MVPA outside the exercise program or increase sedentary time as a result of participating in the exercise program.

Effects of moderate sleep restriction during 8-week calorie restriction on lipoprotein particles and glucose metabolism.

STUDY OBJECTIVES: This study examined how glucose, glucose regulatory hormones, insulin sensitivity, and lipoprotein subclass particle concentrations and sizes change with sleep restriction during weight loss elicited by calorie restriction. METHODS: Overweight or obese adults were randomized into an 8-week calorie restriction intervention alone (CR, n = 12; 75% female; body mass index = 31.4 ± 2.9 kg/m2) or combined with sleep restriction (CR+SR, n = 16; 75% female; body mass index = 34.5 ± 3.1 kg/m2). Participants in both groups were given the same instructions to reduce calorie intake. Those in the CR+SR group were instructed to reduce their habitual time-in-bed by 30-90 minutes 5 days each week with 2 ad libitum sleep days. Fasting venous blood samples were collected at pre- and post-intervention. RESULTS: Differential changes were found between the two groups (p = 0.028 for group × time interaction) in glucagon concentration, which decreased in the CR group (p = 0.016) but did not change in CR+SR group. Although changes in mean HDL particle (HDL-P) size and visfatin concentration were not statistically different between groups (p = 0.066 and 0.066 for group×time interaction, respectively), mean HDL-P size decreased only in the CR+SR group (Cohen's d = 0.50, p = 0.022); visfatin concentrations did not change significantly in either group but appeared to decrease in the CR group (Cohen's d = 0.67, p = 0.170) but not in the CR+SR group (Cohen's d = 0.43, p = 0.225). CONCLUSION: These results suggest that moderate sleep restriction, despite the presence of periodic ad libitum sleep, influences lipoprotein subclass particles and glucose regulation in individuals undergoing calorie restriction.Clinical trial registration: ClinicalTrials.gov (NCT02413866, Weight Outlooks by Restriction of Diet and Sleep).

Influence of sleep restriction on weight loss outcomes associated with caloric restriction.

Study Objectives: To examine the effects of moderate sleep restriction (SR) on body weight, body composition, and metabolic variables in individuals undergoing caloric restriction (CR). Methods: Overweight or obese adults were randomized to an 8 week caloric restriction (CR) regimen alone (n = 15) or combined with sleep restriction (CR + SR) (n = 21). All participants were instructed to restrict daily calorie intake to 95 per cent of their measured resting metabolic rate. Participants in the CR + SR group were also instructed to reduce time in bed on five nights and to sleep ad libitum on the other two nights each week. Results: The CR + SR group reduced sleep by 57 ± 36 min per day during SR days and increased sleep by 59 ± 38 min per day during ad libitum sleep days, resulting in a sleep reduction of 169 ± 75 min per week. The CR and CR + SR groups lost similar amounts of weight, lean mass, and fat mass. However, the proportion of total mass lost as fat was significantly greater (p = 0.016) in the CR group. This proportion was greater than body fat percentage at baseline for the CR (p = 0.0035), but not the CR + SR group. Resting respiratory quotient was reduced (p = 0.033) only in CR, and fasting leptin concentration was reduced only in CR + SR (p = 0.029). Conclusions: Approximately 1 hr of SR on five nights a week led to less proportion of fat mass loss in individuals undergoing hypocaloric weight loss, despite similar weight loss. SR may adversely affect changes in body composition and "catch-up" sleep may not completely reverse it. Clinical trial registration: ClinicalTrials.gov (NCT02413866).