Fifteen-year longitudinal trends in walking patterns and their impact on weight change

Understanding the dynamics of the obesity transition associated with physical activity, sedentary lifestyle, and consumption of ultra-processed foods in Colombia

OBJECTIVE

We investigate the obesity transition at the country- and regional-levels, by age, gender, and socioeconomic status (SES) and its relationship to three health behavior attributes, including physical activity (PA), sedentary activities (ST), and consumption of ultra-processed foods (CUPF) within the urban population of Colombia, from 20,010 to 2050.

METHODS

The study is informed by cross-sectional data from ENSIN survey. We used these data to develop a system dynamics model that simulates the dynamics of obesity by body mass index (BMI) categories, gender, and SES. This model also uses a conservative co-flow structure for three health-related behaviors (PA, ST, and CUPF).

RESULTS

At the national level, our results indicate that the burden of obesity is shifting towards populations with lower SES as the gross domestic product (GDP) increases, particularly women aged 20-59 years with lower SES. Among this group of women, the highest burden of obesity is among those who do not meet the PA, ST and CUPF recommendations. At the regional level, our findings suggest that the regions are at different stages in the obesity transition.

CONCLUSIONS

The burden of obesity is shifting towards women with lower SES as GDP increases at the national level and across several regions. This obesity transition is paralleled by a high prevalence of women from low SES groups who do not meet the minimum recommendations for PA, CUPF, and ST. Our findings can be used by decision-makers to inform age- and SES- specific policies seeking to tackle the obesity.

Differences in Weight Gain Following Residential Relocation in the Moving to Health (M2H) Study

BACKGROUND

Neighborhoods may play an important role in shaping long-term weight trajectory and obesity risk. Studying the impact of moving to another neighborhood may be the most efficient way to determine the impact of the built environment on health. We explored whether residential moves were associated with changes in body weight.

METHODS

Kaiser Permanente Washington electronic health records were used to identify 21,502 members aged 18-64 who moved within King County, WA between 2005 and 2017. We linked body weight measures to environment measures, including population, residential, and street intersection densities (800 m and 1,600 m Euclidian buffers) and access to supermarkets and fast foods (1,600 m and 5,000 m network distances). We used linear mixed models to estimate associations between postmove changes in environment and changes in body weight.

RESULTS

In general, moving from high-density to moderate- or low-density neighborhoods was associated with greater weight gain postmove. For example, those moving from high to low residential density neighborhoods (within 1,600 m) gained an average of 4.5 (95% confidence interval [CI] = 3.0, 5.9) lbs 3 years after moving, whereas those moving from low to high-density neighborhoods gained an average of 1.3 (95% CI = -0.2, 2.9) lbs. Also, those moving from neighborhoods without fast-food access (within 1600m) to other neighborhoods without fast-food access gained less weight (average 1.6 lbs [95% CI = 0.9, 2.4]) than those moving from and to neighborhoods with fast-food access (average 2.8 lbs [95% CI = 2.5, 3.2]).

CONCLUSIONS

Moving to higher-density neighborhoods may be associated with reductions in adult weight gain.

Long-Term Parallel Changes of Physical Activity and Body Mass Index in Different Predisposing Risk Trajectories of Obesity

BACKGROUND

The long-term parallel changes of physical activity and body mass index (BMI) in the adult population are still unclear. The present study assessed the association between physical activity and BMI over time, considering obesity risk trajectory groups and sex strata.

METHODS

Total sample of 6897 adults was followed for an average of 12 years. The reliable and validated Iranian version of the Modifiable Activity Questionnaire measured physical activity. After determining the risk clusters in each reexamination using a 2-step cluster analysis, the latent growth curve modeling was used to identify distinct subgroups of individuals following a similar change of risk cluster over time. Latent growth curve modeling estimated the parameters of cross-sectional, prospective, and parallel associations.

RESULTS

Three trajectories were identified, including stable low risk, unstable risk, and stable high risk. The results showed significant increases in BMI (kg/m2/year) for the stable low-risk trajectory group 0.478 (95% confidence interval [CI] 0.444 to 0.513), unstable risk 0.360 (95% CI, 0.324 to 0.396), and those in the stable high-risk trajectory group 0.255 (95% CI, 0.221 to 0.289). In cross-sectional -0.483 kg/m2 (95% CI, -0.836 to -0.129) and parallel -0.93 kg/m2 (95% CI, -1.862 to 0.00) estimations, significant statistical associations were observed in the stable high-risk trajectory group.

CONCLUSIONS

The current results showed that changes in physical activity could slightly affect BMI only in stable high-risk adults.

Factors associated with changes in physical activity and sedentary behaviour during one year among university-based young adults

The purpose of this study was to identify correlates of changes in physical activity (PA) and sedentary behaviour (SB) among university-based young adults in Bangladesh. Data were from a 1-year prospective study with 2 assessment points (baseline n ​= ​573, 20.7 ​± ​1.35 years, 45% female; retention rate 69%, analytical sample ​= ​395). Participants completed a self-administered written survey on PA, SB, health and lifestyle behaviours, and sociodemographics. Changes in PA were categorised as: negligible (± < 60 ​min/week), > 60 ​min/week decrease, or > 60 ​min/week increase. Changes in SB were categorised as negligible (± < 120 ​min/week), > 120 ​min/week decrease, and > 120 ​min/week increase. Multinomial logistic regression analysis was used to identify the correlates. About quarters (72%) of participants had insufficient PA at both assessment points. Of those who were sufficiently active at Wave 1, 5% became insufficiently active at Wave 2. One quarter of participants (23%) had high SB at Wave 1 and Wave 2. Of those who had low SB at Wave 1, 16% had high SB at Wave 2. Being male [OR ​= ​2.04 (95% CI: 1.06–3.93)], baseline phone time of > 2 h/day [OR ​= ​3.14 (95% CI: 1.04–7.04)] and not participating in organised sports at baseline [OR ​= ​2.56 (95% CI: 1.24–5.29) were associated with a decrease in PA by ​> ​60 ​min/week. Participants who frequently experienced stress at baseline had higher odds of increasing SB by ​> ​120 min/day [OR ​= ​1.83 (95% CI: 1.04–3.23)]. SB is more variable than PA over 1 year in university-based young adults in Bangladesh. Males, those with high phone time, those not engaging with organised sports, and those with frequent stress may change to a more inactive lifestyle.

Physical Activity under Stress: A Perspective of HAPA and Individual Differences

Aims: Physical activity is an effective way for people to cope with stress. However, people often decrease their physical activity in response to stressors. Therefore, we aimed to understand the relationship between perceived stress and physical activity from an outcome expectancies perspective and investigated the moderating role of future orientation in this relationship. Methods: This study recruited 425 students who completed a three-wave survey at six-week intervals. A moderated mediation model was used to examine the mediating effects of outcome expectancies and the moderating effects of future orientation. Results: The results indicated that outcome expectancies mediated the relationship between perceived stress and physical activity. This relationship was moderated by future orientation. In particular, the mediating effects were significant for people with a high future orientation, but not for those with a low future orientation. Conclusion: Our results demonstrate the adaptive function of future orientation in response to general stress. Importantly, the link between perceived stress and reduced physical activity could be mitigated by encouraging people to focus on future consequences. Future studies should consider developing intervention strategies that help those struggling with stressful contexts.

Optimal design of sin taxes in the presence of nontaxable sin goods

Sin good consumption entails health damage, which is in general not fully perceived by individuals, what results in its overconsumption. One way to tackle this problem is to tax these unhealthy goods. However, not all the individual choices that affect health status can be easily observed and effectively taxed by the government. This paper considers a setting where individuals can consume two types of sin goods that differ in their observability (taxability) by the government. As a benchmark, the first-best taxes for the observable and non-observable sin good are derived, considering homogeneous individuals. In the second-best setting, where observability on sin good consumption is limited, the rule for the taxable sin good is shown to depend on the degree of complementarity or substitutability with the unobservable sin good. Finally, redistributional considerations are incorporated by extending the analysis to a setting where individuals differ in their wealth and in their degree of misperception of the health damage caused by sin good consumption. Policy implications are illustrated considering physical inactivity and illicit drugs as examples of non-taxable sin goods, while alcohol, tobacco, fat and sugar account for the taxable sin goods.

Characteristics Associated With People With Chronic Low Back Pain Meeting Physical Activity Guidelines and Recommendations for Sedentary Behavior: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to identify factors associated with meeting physical activity guidelines and sedentary recommendations in people with chronic low back pain (LBP).

METHODS

This was a cross-sectional study including 171 people with chronic LBP. Trained assessors collected information regarding demographic, anthropometric, and clinical data. Physical activity levels and sedentary time were objectively measured using a tri-axial accelerometer. Participants were classified as being physically active (ie, performing at least 150 minutes of moderate or 75 minutes of vigorous physical activity per week) and sedentary (ie, more than 8 hours of time spent in sedentary activities per day). Multivariable logistic regression analyses were used to determine the association of being physically active or sedentary with the range of demographic, anthropometric and clinical variables.

RESULTS

Our results showed that although lower body mass index (odds ratio [OR] = 0.91; 95% CI: 0.85-0.98) and higher self-reported levels of leisure time physical activity (OR = 3.46; 95% CI: 1.94-6.15) were associated with being physically active, lower self-reported levels of physical activity at work (OR = 0.56; 95% CI: 0.39-0.81) was associated with being sedentary.

CONCLUSION

Our findings showed that, in people with LBP, lower body mass index and higher levels of leisure time physical activity may be important factors for identifying those physically active. In contrast, lower levels of physical activity at work may be considered when identifying sedentary people with LBP. Future studies should consider these factors when designing interventions aiming to promote physical activity and decrease sedentary behavior in this population.

Assessing the Rationality and Walkability of Campus Layouts

Walking has become an indispensable and sustainable way of travel for college students in their daily lives and improving the walkability of the college campus will increase the convenience of student life. This paper develops a new campus walkability assessment tool, which optimizes the Walk Score method based on the frequency, variety, and distance of students’ walking to and from public facilities. The campus Walk Score is the product of four components. A preliminary score is calculated through 13 types of facility weight and 3 types of cure of time-decay, and the final score also factors in intersection density and block length. We examine the old and new campuses of Tianjin University to test the tool’s application and evaluate the rationality of facility layout and walkability, and to give suggestions for improvement. The results show that the old campus’ multi-center layout has a high degree of walkability, while the centralized layout of the new campus results in lower walkability. In addition, the diversified distribution of facilities surrounding the old campus promotes the walkability of peripheral places. This assessment tool can help urban planners and campus designers make decisions about how to adjust the facility layout of existing campuses in different regions or to evaluate the campus schemes based on the results of their walkability assessment.

Associations of sitting time with leisure-time physical inactivity, education, and body mass index change

We aimed to investigate the associations of long-term leisure-time physical inactivity, body mass index (BMI) change, and education with sitting time in a 35-year follow-up based on self-reports in surveys. Influences of working status in 2011 and familial confounding on the associations were tested. Data were based on the population-based Finnish Twin Cohort of 5232 twins (53-67-year-old, 41% men) with four surveys in 1975-2011. Statistical analyses were performed using linear regression with several covariates. The effect of familial confounding (genetics and shared environment) was analyzed using a co-twin control design which should be interpreted as if familial confounding plays a role, an association should be seen among all individuals but not in discordant twin pairs. Compared to those not at work, those at work had a longer total sitting time/d. For those at work, higher education was associated with more total sitting but with less non-work sitting. Long-term leisure-time physical inactivity was associated with more non-work sitting among those at work, whereas long-term weight gain with more total and non-work sitting regardless of working status. Familial confounding attenuated the associations, except for the association of increasing BMI with total and non-work sitting among women at work. To conclude, total sitting time was longer among those still at work, but it was also influenced by long-term leisure-time physical inactivity, higher education, and an increase of BMI over the years. Public health efforts should be targeted to reduce sedentary behavior by promoting life-long leisure-time physical activity and weight control.

The Mindfulness App Trial for Weight, Weight-Related Behaviors, and Stress in University Students: Randomized Controlled Trial

Background

University students are at risk of weight gain during their studies. Key factors related to weight gain in this population include unhealthy weight-related behaviors because of stress. Mindfulness holds promise for weight management. However, there has not been any previous trial that has explored the effectiveness of a student-tailored mindfulness app for stress, weight-related behaviors, and weight. There is limited evidence that current mindfulness apps use evidence-based mindfulness techniques. A novel app was developed that combined evidence-based, mindfulness-based stress reduction and mindful eating (ME) techniques that were tailored to university students, with student-relevant themes for targeting weight behaviors, weight, and stress.

Objectives

The aim of this study was to test the effectiveness, acceptability, and feasibility of a student-tailored mindfulness app for weight, weight-related behaviors, and stress. Testing this app in a rigorous randomized controlled trial (RCT) for these outcomes is a novelty and contribution to this emerging field.

Methods

A 2-arm RCT of an 11-week duration was undertaken at the University of Queensland. Students were either randomized to the mindfulness app (n=45) or to a behavioral self-monitoring electronic diary (e-diary; n=45) for diet and exercise. Analysis of covariance was used to compare differences in weight, stress, mindfulness, ME, physical activity, and eating behaviors between both groups.

Results

Neither the mindfulness app group nor the e-diary group lost weight and there were no differences between the groups at follow-up. The mindfulness app group had significantly lower stress levels (P=.02) (adherers only), lower emotional eating (P=.02), and uncontrolled eating (P=.02) as well as higher mindfulness (P≤.001) and ME levels overall (P≤.001). The e-diary group had higher metabolic equivalents of moderate activity levels (P≤.01). However, the effect sizes were small. Regular adherence to mindfulness exercises in the app was low in the group. The majority of students (94%) liked the app and found it to be acceptable. Compared with other exercises, the most helpful reported meditation was the short breathing exercise observing the breath (39.4% [13/33] preferred it).

This was the first RCT that tested a mindfulness app for weight and weight-related behaviors in students. The modest level of user adherence likely contributes to the lack of effect on weight loss. However, there was a small, albeit promising, effect on weight-related eating behavior and stress.

Conclusions

A mindfulness app demonstrated effectiveness for stress, eating behaviors, mindfulness, and ME, but the effect sizes were small. Future studies should be conducted over longer periods of time and with greater participant compliance.

Trial Registration

Australian New Zealand Trial Registry ACTRN12616001349437; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371370 (Archived by WebCite at http://www.webcitation.org/761cc2K6ft)

Factors Affecting Obesity and Waist Circumference Among US Adults

Introduction

Physical activity, sedentary activity, and food intake affect waist circumference and obesity among adults; however, the relationship is unclear. The objective of our study was to explore how these factors affect waist circumference and obesity prevalence among adults.

Methods

We used cross-sectional data from the National Health and Nutrition Examination Survey 2013–2014 on 4,118 adults, 49% men and 51% women, aged 20 to 64 (mean age, 42). Weighted logistic regression models were fitted for abdominal obesity or obesity status and adjusted for variables of demographic characteristics, food intake, types of physical and sedentary activity, television and video viewing, and computer use. Analyses were stratified by sex.

Results

Of the 4,118 people studied, 39% were obese (body mass index ≥30) and 55% had a high-risk waist circumference (hereinafter, abdominal obesity: men, ≥120 cm; women, ≥88 cm). People who watched television or videos 2 hours or more per day had increased odds of being abdominally obese (men, odds ratio [OR], 1.96; 95% confidence interval [CI], 1.29%–2.98%; women, OR, 1.66; 95% CI, 1.06%–2.59%) or obese (men, OR, 2.17; 95% CI, 1.18%–4.02%; women, OR, 1.66; 95% CI, 1.12%–2.48%). After adjusting for types of physical activity, associations remained significant only among men. Moderate recreational physical activity for 150 minutes or more a week versus 149 minutes or less was associated with reduced odds of abdominal obesity for both men (OR, 0.44; 95% CI. 0.22%–0.89%) and women (OR, 0.98; 95% CI, 0.23%–0.67%). Consuming meals prepared away from home was associated with high odds of obesity among women (OR, 1.67; 95% CI, 1.08%–2.58%).

Conclusion

Watching television and videos was positively associated with prevalence of abdominal obesity and obesity among men and women. Prevalence remained significant only among men with inclusion of physical activity. Further study is needed of the differences between the sexes in how physical and sedentary activity and food consumption are associated with obesity.

Metabolic Effects of Preexposure Prophylaxis With Coformulated Tenofovir Disoproxil Fumarate and Emtricitabine

Background

Antiretroviral drugs have been associated with changes in lipids, fat mass and dat distribution. Tenofovir disoproxil fumarate (TDF) has been shown to have a more favorable metabolic profile than other drugs in its class. However, the metabolic effects of TDF in preexposure prophylaxis (PrEP) are unknown.

Methods

We evaluated the effects of TDF/emtricitabine (FTC) on lipids and body composition in a blinded, placebo-controlled PrEP trial. Participants enrolled in a metabolic subcohort (N = 251, TDF/FTC; N = 247, placebo) consented to fasting lipid panels, dual-energy X-ray absorptiometry scans for body composition, and pharmacologic testing of drug metabolites at baseline and every 24 weeks thereafter.

Results

Lean body mass was stable and unaffected by TDF/FTC. Body weight increased in both groups but was lower on TDF/FTC through week 72. This difference was explained by lower fat accumulation on TDF/FTC. The net median percent difference (standard error, P value) for TDF/FTC vs placebo at week 24 was -0.8% (0.4%, P = .02), +0.3% (0.4%, P = .46), and -3.8% (1.4%, P = .009) for total, lean, and fat mass, respectively. There was no apparent differential regional fat accumulation on TDF/FTC. Decreases in cholesterol, but not triglycerides, were seen in TDF/FTC participants, with detectable drug levels compared to placebo.

Conclusions

TDF/FTC for PrEP showed cholesterol reductions and appeared to transiently suppress the accumulation of weight and body fat compared to placebo. There was no evidence of altered fat distribution or lipodystrophy during daily oral TDF/FTC PrEP.

Clinical Trials Registration

NCT00458393.

Leisure-time physical inactivity and association with body mass index: a Finnish Twin Study with a 35-year follow-up

Background

We investigated the stability and change of leisure-time physical inactivity in adult men and women during a 35-year follow-up. We also analysed the impact of long-term physical inactivity on the development of body mass index (BMI).

Methods

: In this population-based cohort study, 5254 Finnish twin individuals (59% women) participated in four surveys in 1975, 1981, 1990 and 2011. Mean age at baseline was 23.9 years. Individual long-term leisure-time physical activity (LTPA) was categorized into seven classes varying from 'persistently inactive' to 'persistently active'. We used the multivariate multilevel mixed-effects linear regression model and paired-sample t-test in the analyses. Co-twin control design was used for examining within-pair associations.

Results

: Of men 11%, and of women 8%, were persistently inactive. Among both sexes, the mean BMI slope trajectories were steeper among the persistently inactive and those who became inactive than among those who were persistently active. Overall, the inactive participants gained 1.4 kg/m 2 [95% confidence interval (CI) 1.2 to 1.7] more in weight than did the active participants from 1975 to 2011. Among twin pairs discordant for LTPA, the corresponding difference was 1.4 kg/m 2 (95% CI 0.83 to 2.0) in dizygotic pairs and 0.68 kg/m 2 (95% CI 0.05 to1.3) in monozygotic pairs.

Conclusions

Over a 35-year time span from young adulthood, persistently inactive participants and those who had become inactive had greater weight increases than those who were persistently active. This association was also found in twin-pair analyses, although attenuated in monozygotic pairs. This may support the importance of LTPA in weight management, although further causal inference is required.

Association between physical activity patterns and anthropometric characteristics of adults: an issue of public health?

Study aim: The aim of this study was to evaluate the association between objectively measured daily physical activity (PA) and body fat mass (BF) and body mass index (BMI). A further aim was to analyse the variance of PA between quartiles of BF and BMI.

Material and methods: A cross-sectional, observational study of 126 university students (53 males aged 20.46 ± 2.04 years and 73 female aged 19.69 ± 1.32 years) was conducted.

Results: The female participants and PA characteristics explain 57.10% of BF variance and the model was statistically signifi­cant (F(6, 875) = 196.38; p = 0.001). BMI was also included in the model. Standard binary logistic regression was used to test the hypothesis that female sex and PA characteristics can influence overweight. The full model containing all variables was statistically significant (G2(6) = 58.598, p-value = 0.001). Analysis of variance between BF quartiles revealed statistically sig­nificant differences in male participants in light PA (p = 0.001; ES = 0.09), moderate PA (p = 0.001; ES = 0.042) and vigorous PA (p = 0.001; ES = 0.130).

Conclusions: The statistical model in the regression analysis suggests that low and vigorous levels of PA explain 57% of BF variance in female participants.

A Prospective Study Comparing Distance-based vs. Time-based Exercise Prescriptions of Walking and Running in Previously Sedentary Overweight Adults

Prior work has reported that the declines observed in body mass index (BMI) and circumference measurements in their cross-sectional data were twice as large when calculated from distance energy expenditure estimations compared to energy expenditure estimations based on time and intensity. The primary purpose of this study was to compare walking/running for distance to walking/running for time as part of an exercise intervention. This study followed a between-subjects, repeated measures design. Fifteen overweight, but otherwise healthy participants completed the study. The time-based group walked/ran for self-reported time while the distance-based group walked/ran for self-reported distance. A mixed-factor repeated-measures ANOVA was used to compare all dependent variables both within-subjects and between-subjects. Weekly adherence rates to the exercise program did not exhibit a significant difference (p > 0.05). Significant interactions were shown for mean body mass loss between groups as well as mean blood glucose level (p < 0.05). Distance-based group exhibited a decline in body mass and blood glucose while the time-based group exhibited an increase in both variables. To the best of the authors' knowledge, the present study is the first to directly compare a distance-based vs. a time-based exercise program for walking and running for improvement of risk factors of cardiovascular disease. The results of this study would suggest that a distance-based exercise prescription of walking or running should provide a clinician or researcher with a closer estimation of overall accumulated exercise and resultant weight loss.

Modeling the Effect of Physical Activity on Obesity in China: Evidence from the Longitudinal China Health and Nutrition Study 1989-2011

Although physical activity has been widely recognized as an important influential factor in determining the risk of obesity, the results in the existing literature empirically examining such issue are mixed. Especially for China, relevant studies are rarely found. One aim of this study is to test the direction of effects between obesity and physical activity. It uses longitudinal data to investigate the relationship and causality between physical activity and obesity for both children and adults in China. The longitudinal data and dynamic panel model used here can yield more solid results than the other studies employing cross-sectional data, particularly considering strict endogeneity and self-selection. It is discovered that obesity does not affect children’s physical activity but that obese children are more sedentary. For adults in China, physical activity can significantly reduce the weight, but not in the opposite direction.

Prevalence and sociodemographic patterns of physical activity among Bangladeshi young adults

BACKGROUND

Physical activity offers physical and psychosocial health benefits that are important during young adulthood and later in life. However, little is known about the physical activity of young adults in low- and middle-income countries. The purpose of this study was to estimate the participation of physical activity in Bangladeshi young adults and to assess differences by gender, age and family income.

METHODS

This cross-sectional study with a self-administered survey used a convenience sample of 573 young adults aged 18-24 years from six purposively selected universities in Dhaka City, Bangladesh. Data were collected during September-November 2015. Medians and their interquartile ranges of weekly time spent in total physical activity, and in different domains of physical activity, were computed. Non-parametric equality of medians test was used to examine gender differences in the median values. Chi-square test and Fisher's exact test were used to examine gender differences in the prevalence of meeting physical activity recommendations and frequency of participation in different leisure-time physical activities, and differences in meeting the activity recommendations by age and family income.

RESULTS

Seventeen percent of the participants were meeting moderate-to-vigorous physical activity (MVPA) recommendations with a significantly higher proportion of males than females (27 vs. 6%, p < .0001). Median duration of MVPA was significantly higher (p < .0001) for males [120 min/week (80, 190)] than females [90 min/week (50, 120)]. Jogging/running was the most commonly reported leisure-time physical activity, with 20% of males and 12% of females doing this at least once a week. Age and family income were not significantly associated with meeting MVPA recommendations.

CONCLUSIONS

Four out of five young adults in Dhaka City did not meet the physical activity recommendations. Additional population-based studies, including regional and metropolitan areas, and using objective measurement, are needed to understand the physical activity patterns of Bangladeshi young adults.

Longitudinal associations between body mass index, physical activity, and healthy dietary behaviors in adults: A parallel latent growth curve modeling approach

Background

Physical activity (PA) and healthy dietary behaviors (HDB) are two well-documented lifestyle factors influencing body mass index (BMI). This study examined 7-year longitudinal associations between changes in PA, HDB, and BMI among adults using a parallel latent growth curve modeling (LGCM).

Methods

We used prospective cohort data collected by a private company (SimplyWell LLC, Omaha, NE, USA) implementing a workplace health screening program. Data from a total of 2,579 adults who provided valid BMI, PA, and HDB information for at least 5 out of 7 follow-up years from the time they entered the program were analyzed. PA and HDB were subjectively measured during an annual online health survey. Height and weight measured during an annual onsite health screening were used to calculate BMI (kg·m²). The parallel LGCMs stratified by gender and baseline weight status (normal: BMI<25, overweight BMI 25–29.9, and obese: BMI>30) were fitted to examine the longitudinal associations of changes in PA and HDB with change in BMI over years.

Results

On average, BMI gradually increased over years, at rates ranging from 0.06 to 0.20 kg·m²·year, with larger increases observed among those of normal baseline weight status across genders. The increases in PA and HDB were independently associated with a smaller increase in BMI for obese males (b = -1.70 and -1.98, respectively), and overweight females (b = -1.85 and -2.46, respectively) and obese females (b = -2.78 and -3.08, respectively). However, no significant associations of baseline PA and HDB with changes in BMI were observed.

Conclusions

Our study suggests that gradual increases in PA and HDB are independently associated with smaller increases in BMI in overweight and obese adults, but not in normal weight individuals. Further study is warranted to address factors that check increases in BMI in normal weight adults.

Path Analysis of Campus Walkability/Bikeability and College Students' Physical Activity Attitudes, Behaviors, and Body Mass Index

PURPOSE

The purpose of this study was to assess the relationship between the walkability/bikeability of college campuses and students' body mass index (BMI) with student physical activity (PA) attitudes and behaviors as potential mediators.

DESIGN

Cross-sectional.

SETTING

Thirteen university campuses.

PARTICIPANTS

A total of 1384 student participants.

MEASURES

Walkability/bikeability environmental score (ES): 12-item audit assessed an average of 44 path segments per campus. Students were measured for height and weight and completed online surveys. Physical activity stage of change/behavior intentions were assessed using the transtheoretical model. The Cognitive Behavioral Physical Activity Questionnaire assessed outcome expectations, self-regulation, and personal barriers. International Physical Activity Questionnaire assessed walking-, moderate-, and vigorous-intensity PA.

ANALYSIS

Descriptive statistics, zero-order correlations, and path analysis with maximum likelihood estimation.

RESULTS

The overall model fit was good with χ² of 171.388 ( df = 18), P < .001, comparative fit index value of .95, and a root mean square of approximation of .079. After controlling for gender, there was a direct negative association between walkability/bikeability ES and BMI (β = -.085) and positive association between personal barriers and BMI (β = .134). Walkability/bikeability ES was positively associated with walking-intensity PA (β = .010). Self-regulation was positively associated with moderate-intensity PA (β = .213), which, in turn, was negatively associated with BMI (β = -.057).

CONCLUSIONS

The ease of walking and biking on a campus was related to college students' walking behavior and their BMI. Students' PA behavioral intentions were associated with moderate PA and lower BMI. These results provide evidence to focus on policies and structural supports for walkable/bikeable environments to supplement and enhance interventions encouraging individual behavior change for PA and weight management.

Determinants of change in body weight and body fat distribution over 5.5 years in a sample of free-living black South African women

Objective

To identify socio-demographic and lifestyle determinants of weight gain in a sample of premenopasual black South African (SA) women.

Methods

Changes in body composition (dual-energy X-ray absorptiometry, computerised tomography), socio-economic status (SES) and behavioural/lifestyle factors were measured in 64 black SA women at baseline (27 ± 8 years) and after 5.5 years.

Results

A lower body mass index (BMI) and nulliparity, together with access to sanitation, were significant determinants of weight gain and change in body fat distribution over 5.5 years. In addition, younger women increased their body weight more than their older counterparts, but this association was not independent of other determinants.

Conclusion

Further research is required to examine the effect of changing SES, as well as the full impact of childbearing on weight gain over time in younger women with lower BMIs. This information will suggest areas for possible intervention to prevent long-term weight gain in these women.

A Comparison of Different Methods for Evaluating Diet, Physical Activity, and Long-Term Weight Gain in 3 Prospective Cohort Studies

BACKGROUND

The insidious pace of long-term weight gain (∼ 1 lb/y or 0.45 kg/y) makes it difficult to study in trials; long-term prospective cohorts provide crucial evidence on its key contributors. Most previous studies have evaluated how prevalent lifestyle habits relate to future weight gain rather than to lifestyle changes, which may be more temporally and physiologically relevant.

OBJECTIVE

Our objective was to evaluate and compare different methodological approaches for investigating diet, physical activity (PA), and long-term weight gain.

METHODS

In 3 prospective cohorts (total n = 117,992), we assessed how lifestyle relates to long-term weight change (up to 24 y of follow-up) in 4-y periods by comparing 3 analytic approaches: 1) prevalent diet and PA and 4-y weight change (prevalent analysis); 2) 4-y changes in diet and PA with a 4-y weight change (change analysis); and 3) 4-y change in diet and PA with weight change in the subsequent 4 y (lagged-change analysis). We compared these approaches and evaluated the consistency across cohorts, magnitudes of associations, and biological plausibility of findings.

RESULTS

Across the 3 methods, consistent, robust, and biologically plausible associations were seen only for the change analysis. Results for prevalent or lagged-change analyses were less consistent across cohorts, smaller in magnitude, and biologically implausible. For example, for each serving of a sugar-sweetened beverage, the observed weight gain was 0.01 lb (95% CI: -0.08, 0.10) [0.005 kg (95% CI: -0.04, 0.05)] based on prevalent analysis; 0.99 lb (95% CI: 0.83, 1.16) [0.45 kg (95% CI: 0.38, 0.53)] based on change analysis; and 0.05 lb (95% CI: -0.10, 0.21) [0.02 kg (95% CI: -0.05, 0.10)] based on lagged-change analysis. Findings were similar for other foods and PA.

CONCLUSIONS

Robust, consistent, and biologically plausible relations between lifestyle and long-term weight gain are seen when evaluating lifestyle changes and weight changes in discrete periods rather than in prevalent lifestyle or lagged changes. These findings inform the optimal methods for evaluating lifestyle and long-term weight gain and the potential for bias when other methods are used.

Worksite neighborhood and obesogenic behaviors: findings among employees in the Promoting Activity and Changes in Eating (PACE) trial

BACKGROUND

Understanding mechanisms linking neighborhood context to health behaviors may provide targets for increasing lifestyle intervention effectiveness. Although associations between home neighborhood and obesogenic behaviors have been studied, less is known about the role of worksite neighborhood.

PURPOSE

To evaluate associations between worksite neighborhood context at baseline (2006) and change in obesogenic behaviors of adult employees at follow-up (2007-2009) in a worksite randomized trial to prevent weight gain.

METHODS

Worksite property values were used as an indicator of worksite neighborhood SES (NSES). Worksite neighborhood built environment attributes associated with walkability were evaluated as explanatory factors in relationships among worksite NSES, diet, and physical activity behaviors of employees. Behavioral data were collected at baseline (2005-2007) and follow-up (2007-2009). Multilevel linear and logistic models were constructed adjusting for covariates and accounting for clustering within worksites. Product-of-coefficients methods were used to assess mediation. Analyses were performed after study completion (2011-2012).

RESULTS

Higher worksite NSES was associated with more walking (OR=1.16, 95% CI=1.03, 1.30, p=0.01). Higher density of residential units surrounding worksites was associated with more walking and eating five or more daily servings of fruits and vegetables, independent of worksite NSES. Residential density partially explained relationships among worksite NSES, fruit and vegetable consumption, and walking.

CONCLUSIONS

Worksite neighborhood context may influence employees' obesogenic behaviors. Furthermore, residential density around worksites could be an indicator of access to dietary and physical activity-related infrastructure in urban areas. This may be important given the popularity of worksites as venues for obesity prevention efforts.

Sedentary versus active leisure activities and their relationship with sleeping habits and body mass index in children of 9 and 10 years of age

A random sample of 291 9- and 10-year-old schoolchildren from Asturias (Spain) was taken. Using path analysis, a model was tested in which bedtime, the number of hours spent sleeping and leisure activities were the independent variables and the body mass index was the dependent variable. The results show that sedentary and active leisure time and hours spent sleeping are predictors of the body mass index in children. Those children who go to bed late and who use that extra time to watch the television or play with the computer tend to have a greater body mass index, while those children who go to bed earlier and have spent more time reading or playing in the park or at home have a lower body mass index. Encouraging active leisure activities can have an extremely positive effect on their body mass index.

The effect of physical activity on adult obesity: evidence from the Canadian NPHS panel

Although physical activity has been considered as an important modifiable risk factor for obesity, the empirical evidence on the relationship between physical activity and obesity is mixed. Observational studies in the public health literature fail to account for time-invariant unobserved heterogeneity and dynamics of weight, leading to biased estimation of the effect of physical activity on obesity. To overcome this limitation, we propose dynamic fixed-effects models to account for unobserved heterogeneity bias and the dynamics of obesity. We use nationally representative longitudinal data on the cohort of adults aged 18-50 years in 1994/95 from Canada's National Population Health Survey and followed them over 16 years. Obesity is measured by BMI (body mass index). After controlling for a wide range of socio-economic factors, the impact of four alternative measures of leisure-time physical activity (LTPA) and work-related physical activity (WRPA) are analyzed. The results show that each measure of LTPA exerts a negative effect on BMI and the effects are larger for females. Our key results show that participation in LTPA exceeding 1.5 kcal/kg per day (i.e., at least 30 min of walking) reduces BMI by about 0.11-0.14 points in males and 0.20 points in females relative to physically inactive counterparts. Compared to those who are inactive at workplace, being able to stand or walk at work is associated with a reduction in BMI in the range of 0.16-0.19 points in males and 0.24-0.28 points in females. Lifting loads at workplace is associated with a reduction in BMI by 0.2-0.3 points in males and 0.3-0.4 points in females relative to those who are reported sedentary. Policies aimed at promotion of LTPA combined with WRPA like walking or climbing stairs daily would help reduce adult obesity risks.

Weight-related disparities for transgender college students

OBJECTIVE

The objective of this study was to explore disparities in weight and weight-related behaviors by transgender identity.

METHODS

Cross-sectional regression models were fit using 2007-2011 College Student Health Survey data.

RESULTS

Compared to non-transgender, transgender subjects (N=53) were more likely to be either underweight [adjusted relative risk (95% CI): 4.78 (1.61-14.18)] or obese [2.45 (1.21-4.93)], and less likely to meet recommendations for strenuous physical activity [1.16 (1.01-1.34)], strengthening physical activity [1.32 (1.11-1.56)], and screen time [1.20 (1.02-1.41)].

CONCLUSIONS

More research is needed to understand the unique social contexts of transgender college students with regard to weight status, physical activity, and screen time in order to effectively inform intervention and policy development and implementation.

Predictors of change in weight and waist circumference: 15-year longitudinal study in Australian adults

BACKGROUND/OBJECTIVES

This study examines which socio-demographic and lifestyle characteristics are associated with weight and waist circumference (WC) change in a cohort of Australian adults over a 15-year period (1992-2007). Further, it tests the effect of period of birth (birth cohort) on mean weight and WC at two time points, 15 years apart.

SUBJECTS/METHODS

Up to three repeated measures of weight (n=1437) and WC (n=1317) were used. Self-reported data on socio-demographic and lifestyle characteristics were derived from repeated questionnaires. Multivariable models, stratified by sex, were adjusted for potential confounders.

RESULTS

Participants born more recently were heavier, on average, than those in the same age group 15 years earlier, but there was no such secular trend in WC. Age at baseline was associated with change in weight and WC, but the pattern was different: participants gained weight up to age 55 years, while WC gain continued to 65 years. In women, higher level of recreational physical activity was associated with lower WC gain (P<0.05). Parity was also associated with WC change in women (P<0.05), but there was no linear trend.

CONCLUSIONS

Age was the most important factor associated with change in weight and WC in both sexes, apparently reducing the influence of all potential covariates. Among women, physical activity and parity were also associated with change in weight and WC. This study provides longitudinal evidence to support public health efforts that address the continuous increases in average weight and WC of many populations around the world.

Dietary and lifestyle characteristics associated with normal-weight obesity: the National FINRISK 2007 Study

The aim of the present study was to compare the lifestyle (leisure-time physical activity, smoking habits and alcohol consumption) and dietary (energy-yielding nutrients, dietary fibre and foods) factors of Finns with a new syndrome called normal-weight obesity (NWO) with those of lean and overweight Finns. The representative population-based study included 4786 participants (25-74 years) from the National FINRISK 2007 Study with a health examination and questionnaires. Food intake was assessed using a validated FFQ. NWO was defined to include those with a normal BMI (<25 kg/m²) but excessive body fat (for men ≥20 % and for women ≥30 %) according to WHO definitions. The proportion of participants with a normal BMI was 28 % in men and 42 % in women. Of these, 34 % of the men and 45 % of the women had the NWO syndrome (among all the participants, 10 and 19 %, respectively). The waist circumference of the NWO participants was between that of the lean and overweight participants. Some potential risk factors, such as physical inactivity, (ex)-smoking and alcohol consumption, were related to NWO. In general, the intakes of energy-yielding nutrients were not associated with NWO. Instead, some healthy dietary factors (e.g. low intakes of meat and soft drinks) as well as unhealthy factors (e.g. low intakes of root vegetables, cereals and fish and high intake of confectionery) were related to NWO. The findings might explain why the NWO participants were of normal weight, but had an excessive body fat percentage. In conclusion, the proportion of normal-weight participants with an excessive body fat percentage was surprisingly high. The identification of NWO people may be of importance because although they appear lean, they have some unhealthy lifestyle and dietary habits related to obesity and overall health.

Long-term health benefits of physical activity--a systematic review of longitudinal studies

BACKGROUND

The treatment of noncommunicable diseases (NCD), like coronary heart disease or type 2 diabetes mellitus, causes rising costs for the health system. Physical activity is supposed to reduce the risk for these diseases. Results of cross-sectional studies showed that physical activity is associated with better health, and that physical activity could prevent the development of these diseases. The purpose of this review is to summarize existing evidence for the long-term (>5 years) relationship between physical activity and weight gain, obesity, coronary heart disease, type 2 diabetes mellitus, Alzheimer's disease and dementia.

METHODS

Fifteen longitudinal studies with at least 5-year follow up times and a total of 288,724 subjects (>500 participants in each study), aged between 18 and 85 years, were identified using digital databases. Only studies published in English, about healthy adults at baseline, intentional physical activity and the listed NCDs were included.

RESULTS

The results of these studies show that physical activity appears to have a positive long-term influence on all selected diseases.

CONCLUSIONS

This review revealed a paucity of long-term studies on the relationship between physical activity and the incidence of NCD.

Physical activity and the incidence of obesity in young African-American women

BACKGROUND

Obesity occurs more commonly among African-American women than among other racial/ethnic groups, and most weight gain occurs before middle age.

PURPOSE

The study prospectively investigated the relationship of vigorous exercise and brisk walking to the incidence of obesity (BMI ≥ 30) among African-American women aged <40 years.

METHODS

During 1995-2009 in the Black Women's Health Study, the current authors followed 20,259 African-American women who were aged <40 years and not obese at baseline. BMI, exercise, and walking were assessed at baseline and on biennial follow-up questionnaires. Data for BMI were collected through 2009. Data for exercise and walking were collected through 2007. Validation and reproducibility data indicated that reporting was more accurate for vigorous exercise than for brisk walking. Cox proportional hazards models estimated incidence rate ratios (IRRs) and 95% CIs of incident obesity for hours/week of vigorous exercise and walking relative to "little or no exercise" (<1 hour/week of vigorous exercise and <1 hour/week of brisk walking). The analyses were conducted in 2012.

RESULTS

The incidence of obesity decreased with increasing vigorous exercise; the IRR was 0.77 (95% CI=0.69, 0.85) for ≥ 7 hours/week relative to little or no exercise; the IRRs were reduced both among women with a healthy weight (BMI <25) at baseline and among women who were overweight (BMI 25-<30) at baseline. The IRRs for brisk walking for exercise and walking for transport were <1.0 for most levels of walking, but without clear trends of decreasing risk with increasing time spent walking.

CONCLUSIONS

The results suggest that vigorous exercise may reduce the incidence of obesity among young African-American women. Results for brisk walking were inconclusive.

Advantage of distance- versus time-based estimates of walking in predicting adiposity

PURPOSE

Physical activity recommendations are defined in terms of time spent being physically active (e.g., 30 min of brisk walking, 5 d · wk(-1)). However, walking volume may be more naturally assessed by distance than by time. Analyses were therefore performed to test whether time or distance provides the best metric for relating walking volume to estimated total and regional adiposity.

METHODS

Linear and logistic regression analyses were used to relate exercise dose to body mass index (BMI), body circumferences, and obesity in a cross-sectional sample of 12,384 female and 3434 male walkers who reported both usual distance walked and time spent walking per week on survey questionnaires. Metabolic equivalent hours per day (MET · h · d(-1), 1 MET = 3.5 mL O2 · kg(-1) · min(-1)) were calculated from the time and pace, or distance and pace, using published compendium values.

RESULTS

Average MET-hours per day walked was 37% greater when calculated from time spent walking versus usual distance in women and was 32% greater in men. Per MET-hours per day, declines in BMI and circumferences (slope ± SE) were nearly twice as great, or greater, for distance- versus time-derived estimates for kilograms per squared meter of BMI (females = -0.58 ± 0.03 vs -0.31 ± 0.02, males = -0.35 ± 0.04 vs -0.15 ± 0.02), centimeter of waist circumference (females = -1.42 ± 0.07 vs -0.72 ± 0.04, males = -0.96 ± 0.10 vs -0.45 ± 0.07), and reductions in the odds for total obesity (odds ratio: females = 0.72 vs 0.84, males = 0.84 vs 0.92) and abdominal obesity (females = 0.74 vs 0.85, males = 0.79 vs 0.91, all comparisons significant).

CONCLUSIONS

Distance walked may provide a better metric of walking volume for epidemiologic obesity research, and better public health targets for weight control, than walking duration. Additional research is required to determine whether these results, derived in a sample that regularly walks for exercise, apply more generally.

[Physical activity and obesity]

One reason for the high prevalence of overweight and obesity might be the differences in lifestyle compared to earlier decades, called the "obesogenic environment." With this, the decline in physical activity (PA) in favor of a sedentary lifestyle is assumed to play an important role. Physical activity or inactivity has a major impact on the development of overweight and obesity as well as on certain metabolic disorders. This review summarizes current scientific knowledge regarding the association between PA and overweight/obesity. The term "physical activity" is defined and different methods of its assessment are introduced. In addition, certain methods for the evaluation/operationalization of collected PA data are described. Finally, some epidemiological studies dealing with the associations between PA and overweight/obesity in children/adolescents as well as in adults are presented.

Active transport, physical activity, and body weight in adults: a systematic review

CONTEXT

Physical activity has various health benefits. Active transport can contribute to total physical activity and thus affect body weight because of increased energy expenditure. This review summarizes published evidence on associations of active transport, general physical activity, and body weight in adults.

EVIDENCE ACQUISITION

A systematic review of the literature was conducted in October 2010 using eight databases. A total of 14,216 references were screened; full texts were retrieved for 95 articles. Forty-six articles (36 unique studies) were included: 20 (17) from Europe; 18 (13) from North America, Australia, and New Zealand; and eight (six) from other countries. Analyses of the retrieved papers were carried out between November 2010 and March 2011.

EVIDENCE SYNTHESIS

Of 15 studies assessing active transport and physical activity, five found associations in the expected direction (more active transport associated with more physical activity) for all or most variables studied, nine found some associations, and one reported no associations. Of 30 studies assessing active transport and body weight, 13 reported associations in the expected direction (more active transport associated with lower body weight) for all or most variables studied, 12 found some associations, two presented some associations in the expected and some in the opposite direction, and three reported no associations.

CONCLUSIONS

There is limited evidence that active transport is associated with more physical activity as well as lower body weight in adults. However, study heterogeneity, predominantly cross-sectional designs, and crude measures for active transport and physical activity impede quantitative conclusions.

The efficacy and cost-effectiveness of a community weight management intervention: a randomized controlled trial of the health weight management demonstration

PURPOSE

The study investigated the efficacy and cost-effectiveness of a cognitive-behavioral weight management program, complemented by an interactive Web site and brief telephone/e-mail coaching.

METHODS

In 2006-2007, 1755 overweight, non-active-duty TRICARE beneficiaries were randomized to one of three conditions with increasing intervention intensity: written materials and basic Web access (RCT1), plus an interactive Web site (RCT2), plus brief telephone/e-mail coaching support (RCT3). The study assessed changes in weight, blood pressure, and physical activity from baseline to 6, 12, and 15-18 months. (Study retention was 31% at 12 months.) Average and incremental cost-effectiveness and cost-offset analyses were conducted.

RESULTS

Participants experienced significant weight loss (-4.0%, -4.0%, and -5.3%, respectively, in each RCT group after 12 months and -3.5%, -3.8%, and -5.1%, respectively, after 15 to 18 months), increased physical activity, and decreased blood pressure. Cost-effectiveness ratios were $900 to $1100/quality-adjusted life year (QALY) for RCT1 and RCT2 and $1900/QALY for RCT3. The cost recovery period to the government was 3 years for RCTs 1 and 2 and 6 years for RCT3.

CONCLUSION

A relatively inexpensive cognitive-behavioral weight management intervention improved patient outcomes. Extrapolation of savings for the entire TRICARE population would significantly reduce direct medical costs.

An economic analysis of community-level fast food prices and individual-level fast food intake: a longitudinal study

BACKGROUND

While dietary intake is shaped by cost, there is minimal research on the association between community-level food prices and dietary intake.

METHODS

We used nationally representative, longitudinal data to examine how community-level food price variation was associated with individual-level fast food intake by race/ethnicity and income across waves II (1996) and III (2001-2002) of the National Longitudinal Study of Adolescent Health (n=11,088) from 158 baseline and 363 follow-up US counties.

RESULTS

Negative binomial regression models predicting the number of fast food meals per week show strong relationships between fast food consumption and prices of fast food and soda that varied by gender and race/ethnicity. We found relatively stronger association between food prices and fast food intake for males and relatively greater price sensitivity for soda versus burgers. In the group with strongest associations (black males), a 20% increase in the price of soda was associated with a decrease of 0.25 visits to a fast food restaurant per week.

CONCLUSIONS

Economic incentives may be an effective mechanism to address fast food intake in an age group at high risk for obesity.

Changes in diet and lifestyle and long-term weight gain in women and men

BACKGROUND

Specific dietary and other lifestyle behaviors may affect the success of the straightforward-sounding strategy "eat less and exercise more" for preventing long-term weight gain.

METHODS

We performed prospective investigations involving three separate cohorts that included 120,877 U.S. women and men who were free of chronic diseases and not obese at baseline, with follow-up periods from 1986 to 2006, 1991 to 2003, and 1986 to 2006. The relationships between changes in lifestyle factors and weight change were evaluated at 4-year intervals, with multivariable adjustments made for age, baseline body-mass index for each period, and all lifestyle factors simultaneously. Cohort-specific and sex-specific results were similar and were pooled with the use of an inverse-variance-weighted meta-analysis.

RESULTS

Within each 4-year period, participants gained an average of 3.35 lb (5th to 95th percentile, -4.1 to 12.4). On the basis of increased daily servings of individual dietary components, 4-year weight change was most strongly associated with the intake of potato chips (1.69 lb), potatoes (1.28 lb), sugar-sweetened beverages (1.00 lb), unprocessed red meats (0.95 lb), and processed meats (0.93 lb) and was inversely associated with the intake of vegetables (-0.22 lb), whole grains (-0.37 lb), fruits (-0.49 lb), nuts (-0.57 lb), and yogurt (-0.82 lb) (P≤0.005 for each comparison). Aggregate dietary changes were associated with substantial differences in weight change (3.93 lb across quintiles of dietary change). Other lifestyle factors were also independently associated with weight change (P<0.001), including physical activity (-1.76 lb across quintiles); alcohol use (0.41 lb per drink per day), smoking (new quitters, 5.17 lb; former smokers, 0.14 lb), sleep (more weight gain with <6 or >8 hours of sleep), and television watching (0.31 lb per hour per day).

CONCLUSIONS

Specific dietary and lifestyle factors are independently associated with long-term weight gain, with a substantial aggregate effect and implications for strategies to prevent obesity. (Funded by the National Institutes of Health and others.).

Spontaneous physical activity protects against fat mass gain

It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long-term.

Improving health through policies that promote active travel: a review of evidence to support integrated health impact assessment

BACKGROUND

Substantial policy changes to control obesity, limit chronic disease, and reduce air pollution emissions, including greenhouse gasses, have been recommended. Transportation and planning policies that promote active travel by walking and cycling can contribute to these goals, potentially yielding further co-benefits. Little is known, however, about the interconnections among effects of policies considered, including potential unintended consequences.

OBJECTIVES AND METHODS

We review available literature regarding health impacts from policies that encourage active travel in the context of developing health impact assessment (HIA) models to help decision-makers propose better solutions for healthy environments. We identify important components of HIA models of modal shifts in active travel in response to transport policies and interventions.

RESULTS AND DISCUSSION

Policies that increase active travel are likely to generate large individual health benefits through increases in physical activity for active travelers. Smaller, but population-wide benefits could accrue through reductions in air and noise pollution. Depending on conditions of policy implementations, risk tradeoffs are possible for some individuals who shift to active travel and consequently increase inhalation of air pollutants and exposure to traffic injuries. Well-designed policies may enhance health benefits through indirect outcomes such as improved social capital and diet, but these synergies are not sufficiently well understood to allow quantification at this time.

CONCLUSION

Evaluating impacts of active travel policies is highly complex; however, many associations can be quantified. Identifying health-maximizing policies and conditions requires integrated HIAs.

Mismatch between perceived and objectively assessed neighborhood walkability attributes: prospective relationships with walking and weight gain

We examined prospectively whether persons who perceive their objectively measured high walkable environment as low walkable decrease their walking more and gain more weight than those with matched perceptions. Walkability was measured objectively using GIS. Corresponding perceptions were collected using the Neighborhood Environment Walkability Scale from 1027 urban Australian adults. Objective and perceived measures were dichotomized and categories of match and mismatch were created. Overall, walking levels decreased and BMI increased significantly over the four year follow-up period. Those who perceived high walkability, dwelling density or land use mix as low decreased their walking for transport significantly more than those with matched perceptions. Those who perceived high walkability, land use mix or retail density as low increased their BMI significantly more than those with concordant perceptions. These prospective findings corroborate recommendations from previous cross-sectional studies. Interventions to improve negative perceptions of walkability among those living in high walkable areas may be a relevant public health intervention to increase physical activity and support weight maintenance.

Maintaining a high physical activity level over 20 years and weight gain

CONTEXT

Data supporting physical activity guidelines to prevent long-term weight gain are sparse, particularly during the period when the highest risk of weight gain occurs.

OBJECTIVE

To evaluate the relationship between habitual activity levels and changes in body mass index (BMI) and waist circumference over 20 years.

DESIGN, SETTING, AND PARTICIPANTS

The Coronary Artery Risk Development in Young Adults (CARDIA) study is a prospective longitudinal study with 20 years of follow-up, 1985-1986 to 2005-2006. Habitual activity was defined as maintaining high, moderate, and low activity levels based on sex-specific tertiles of activity scores at baseline. Participants comprised a population-based multicenter cohort (Chicago, Illinois; Birmingham, Alabama; Minneapolis, Minnesota; and Oakland, California) of 3554 men and women aged 18 to 30 years at baseline.

MAIN OUTCOME MEASURES

Average annual changes in BMI and waist circumference.

RESULTS

Over 20 years, maintaining high levels of activity was associated with smaller gains in BMI and waist circumference compared with low activity levels after adjustment for race, baseline BMI, age, education, cigarette smoking status, alcohol use, and energy intake. Men maintaining high activity gained 2.6 fewer kilograms (0.15 BMI units per year; 95% confidence interval [CI], 0.11-0.18 vs 0.20 in the lower activity group; 95% CI, 0.17-0.23), and women maintaining higher activity gained 6.1 fewer kilograms (0.17 BMI units per year; 95% CI, 0.12-0.21 vs 0.30 in the lower activity group; 95% CI, 0.25-0.34). Men maintaining high activity gained 3.1 fewer centimeters in waist circumference (0.52 cm per year; 95% CI, 0.43-0.61 cm vs 0.67 cm in the lower activity group; 95% CI,0.60-0.75 cm) and women maintaining higher activity gained 3.8 fewer centimeters(0.49 cm per year; 95% CI, 0.39-0.58 cm vs 0.67 cm in the lower activity group; 95% CI, 0.60-0.75 cm) [corrected].

CONCLUSION

Maintaining high activity levels through young adulthood may lessen weight gain as young adults transition to middle age, particularly in women.

Prevalence and predictors of weight-loss maintenance in a biracial cohort: results from the coronary artery risk development in young adults study

BACKGROUND

Few population-based studies have examined the behavioral and psychosocial predictors of long-term weight-loss maintenance.

PURPOSE

The goal of this study was to determine the prevalence and predictors of weight-loss maintenance in a biracial cohort of younger adults.

METHODS

This study examined a population-based sample of overweight/obese African-American and white men and women who had ≥ 5% weight loss between 1995 and 2000. Subsequent changes in weight, physical activity, and behavioral and psychosocial factors were examined between 2000 and 2005. Analyses were conducted in 2008-2009.

RESULTS

Among the 1869 overweight/obese individuals without major disease in 1995, a total of 536 (29%) lost ≥ 5% between 1995 and 2000. Among those who lost weight, 34% (n=180) maintained at least 75% of their weight loss between 2000 and 2005, whereas 66% subsequently regained. Higher odds of successful weight-loss maintenance were related to African-American race (OR=1.7, p=0.03); smoking (OR=3.4, p=0.0001); history of diabetes (OR=2.2, p=0.04); increases in moderate physical activity between 2000 and 2005 (OR=1.4, p=0.005); increases in emotional support over the same period (OR=1.6, p=0.01); and less sugar-sweetened soft drink consumption in 2005 (OR=0.8, p=0.006).

CONCLUSIONS

One third of overweight men and women who lost weight were able to maintain 75% or more of their weight loss over 5 years. Interventions to promote weight-loss maintenance may benefit from targeting increased physical activity and emotional support and decreased sugar-sweetened soft drink consumption.

Effect of sibutramine on cardiovascular outcomes in overweight and obese subjects

BACKGROUND

The long-term effects of sibutramine treatment on the rates of cardiovascular events and cardiovascular death among subjects at high cardiovascular risk have not been established.

METHODS

We enrolled in our study 10,744 overweight or obese subjects, 55 years of age or older, with preexisting cardiovascular disease, type 2 diabetes mellitus, or both to assess the cardiovascular consequences of weight management with and without sibutramine in subjects at high risk for cardiovascular events. All the subjects received sibutramine in addition to participating in a weight-management program during a 6-week, single-blind, lead-in period, after which 9804 subjects underwent random assignment in a double-blind fashion to sibutramine (4906 subjects) or placebo (4898 subjects). The primary end point was the time from randomization to the first occurrence of a primary outcome event (nonfatal myocardial infarction, nonfatal stroke, resuscitation after cardiac arrest, or cardiovascular death).

RESULTS

The mean duration of treatment was 3.4 years. The mean weight loss during the lead-in period was 2.6 kg; after randomization, the subjects in the sibutramine group achieved and maintained further weight reduction (mean, 1.7 kg). The mean blood pressure decreased in both groups, with greater reductions in the placebo group than in the sibutramine group (mean difference, 1.2/1.4 mm Hg). The risk of a primary outcome event was 11.4% in the sibutramine group as compared with 10.0% in the placebo group (hazard ratio, 1.16; 95% confidence interval [CI], 1.03 to 1.31; P=0.02). The rates of nonfatal myocardial infarction and nonfatal stroke were 4.1% and 2.6% in the sibutramine group and 3.2% and 1.9% in the placebo group, respectively (hazard ratio for nonfatal myocardial infarction, 1.28; 95% CI, 1.04 to 1.57; P=0.02; hazard ratio for nonfatal stroke, 1.36; 95% CI, 1.04 to 1.77; P=0.03). The rates of cardiovascular death and death from any cause were not increased.

CONCLUSIONS

Subjects with preexisting cardiovascular conditions who were receiving long-term sibutramine treatment had an increased risk of nonfatal myocardial infarction and nonfatal stroke but not of cardiovascular death or death from any cause. (Funded by Abbott; ClinicalTrials.gov number, NCT00234832.)

Bicycle riding, walking, and weight gain in premenopausal women

BACKGROUND

To our knowledge, research has not been conducted on bicycle riding and weight control in comparison with walking. Our objective was to assess the association between bicycle riding and weight control in premenopausal women.

METHODS

This was a 16-year follow-up study of 18,414 women in the Nurses' Health Study II. Weight change between 1989 and 2005 was the primary outcome, and the odds of gaining more than 5% of baseline body weight by 2005 was the secondary outcome.

RESULTS

At baseline, only 39% of participants walked briskly, while only 1.2% bicycled for more than 30 min/d. For a 30-min/d increase in activity between 1989 and 2005, weight gain was significantly less for brisk walking (-1.81 kg; 95% confidence interval [CI], -2.05 to -1.56 kg), bicycling (-1.59 kg; 95% CI, -2.09 to -1.08 kg), and other activities (-1.45 kg; 95% CI, -1.66 to -1.24 kg) but not for slow walking (+0.06 kg; 95% CI, -0.22 to 0.35 kg). Women who reported no bicycling in 1989 and increased to as little as 5 min/d in 2005 gained less weight (-0.74 kg; 95% CI, -1.41 to -0.07 kg; P value for trend, <.01) than those who remained nonbikers. Normal-weight women who bicycled more than 4 h/wk in 2005 had a lower odds of gaining more than 5% of their baseline body weight (odds ratio, 0.74; 95% CI, 0.56 to 0.98) compared with those who reported no bicycling; overweight and obese women had a lower odds at 2 to 3 h/wk (odds ratio, 0.54; 95% CI, 0.34 to 0.86).

CONCLUSIONS

Bicycling, similar to brisk walking, is associated with less weight gain and an inverse dose-response relationship exists, especially among overweight and obese women. Future research should focus on brisk walking and greater time spent bicycling.

Differences of energy expenditure and physical activity patterns in subjects with various degrees of obesity

BACKGROUND & AIMS

An imbalance of energy intake and energy expenditure leads to obesity. However, little detailed information of energy expenditure and physical activity patterns in obese subjects is available. Therefore, we assessed total energy expenditure (TEE) with its components resting energy expenditure (REE) and activity thermogenesis (AT) and the patterns of physical activity in non-obese and in subjects with different degrees of obesity.

METHODS

TEE and activity pattern were assessed with the SenseWear™ armband in 78 subjects (46 ± 12 years; 28 with normal weight/overweight, 13 each with obesity I° and II°, and 24 with obesity III°). In addition, REE was measured by indirect calorimetry and AT was calculated.

RESULTS

Although TEE (and REE) increased with increasing weight category from 2567 (1437) kcal/d in non-obese subjects to 3033 (1931) kcal/d in subjects with obesity III° (p=0.016, p<0.001, respectively) body weight adjusted TEE decreased from 33.1 to 22.1 kcal/kg/d (p<0.001). This was mainly due to decreased body weight adjusted AT (11.3-5.8 kcal/kg/d, p<0.001). AT consisted almost completely of non-exercise AT. In particular, for obese subjects exercise-related AT was negligible.

CONCLUSIONS

Higher degrees of obesity are associated with decreased body weight adjusted AT. These differences have to be considered for therapeutic strategies.

Long-term cost-effectiveness of weight management in primary care

BACKGROUND

As obesity prevalence and health-care costs increase, Health Care providers must prevent and manage obesity cost-effectively.

METHODS

Using the 2006 NICE obesity health economic model, a primary care weight management programme (Counterweight) was analysed, evaluating costs and outcomes associated with weight gain for three obesity-related conditions (type 2 diabetes, coronary heart disease, colon cancer). Sensitivity analyses examined different scenarios of weight loss and background (untreated) weight gain.

RESULTS

Mean weight changes in Counterweight attenders was -3 kg and -2.3 kg at 12 and 24 months, both 4 kg below the expected 1 kg/year background weight gain. Counterweight delivery cost was pound59.83 per patient entered. Even assuming drop-outs/non-attenders at 12 months (55%) lost no weight and gained at the background rate, Counterweight was 'dominant' (cost-saving) under 'base-case scenario', where 12-month achieved weight loss was entirely regained over the next 2 years, returning to the expected background weight gain of 1 kg/year. Quality-adjusted Life-Year cost was pound2017 where background weight gain was limited to 0.5 kg/year, and pound2651 at 0.3 kg/year. Under a 'best-case scenario', where weights of 12-month-attenders were assumed thereafter to rise at the background rate, 4 kg below non-intervention trajectory (very close to the observed weight change), Counterweight remained 'dominant' with background weight gains 1 kg, 0.5 kg or 0.3 kg/year.

CONCLUSION

Weight management for obesity in primary care is highly cost-effective even considering only three clinical consequences. Reduced healthcare resources use could offset the total cost of providing the Counterweight Programme, as well as bringing multiple health and Quality of Life benefits.

Hypocretin/orexin and energy expenditure

The hypocretins or orexins are endogenous neuropeptides synthesized in discrete lateral, perifornical and dorsal hypothalamic neurones. These multi-functional neuropeptides modulate energy homeostasis, arousal, stress, reward, reproduction and cardiovascular function. This review summarizes the role of hypocretins in modulating non-sleep-related energy expenditure with specific focus on the augmentation of whole body energy expenditure as well as hypocretin-induced physical activity and sympathetic outflow. We compare the efficacy of hypocretin-1 and 2 on energy expenditure and evaluate whether the literature implicates hypocretin signalling though the hypocretin-1 and -2 receptor as having shared and or functionally specific physiological effects. Thus far data suggest that hypocretin-1 has a more robust stimulatory effect relative to hypocretin-2. Furthermore, hypocretin-1 receptor predominantly mediates behaviours known to influence energy expenditure. Further studies on the hypocretin-2 receptor are needed.

Adherence to a behavioral weight loss treatment program enhances weight loss and improvements in biomarkers

OBJECTIVES

To describe participants' adherence to multiple components (attendance, energy intake, fat gram, exercise goals, and self-monitoring eating and exercise behaviors) of a standard behavioral treatment program (SBT) for weight loss and how adherence to these components may influence weight loss and biomarkers (triglycerides, low density lipoproteins [LDL], high density lipoprotein, and insulin) during the intensive and less-intensive intervention phases.

METHODS

A secondary analysis of a randomized clinical trial consisting of a SBT with either fat-restricted standard or lacto-ovo vegetarian diet. The 12-month intervention was delivered in 33 group sessions. The first six months reflected the intensive phase; the second six months, the less-intensive intervention phase. We conducted the analysis without regard to treatment assignment. Eligible participants included overweight/obese adults (N = 176; mean body mass index = 34.0 kg/m(2)). The sample was 86.9% female, 70.5% White, and 44.4 +/- 8.6 years old. The outcome measures included weight and biomarkers.

RESULTS

There was a significant decline in adherence to each treatment component over time (P < 0.0001). In the first six months, adherence to attendance, self-monitoring and the energy goal were significantly associated with greater weight loss (P < 0.05). Adherence to attendance and exercise remained significantly associated with weight loss in the second six months (P < 0.05). Adherence to attendance, self-monitoring and exercise had indirect effects through weight loss on LDL, triglycerides, and insulin (P < 0.05).

CONCLUSIONS

We observed a decline in adherence to each treatment component as the intervention intensity was reduced. Adherence to multiple treatment components was associated with greater weight loss and improvements in biomarkers. Future research needs to focus on improving and maintaining adherence to all components of the treatment protocol to promote weight loss and maintenance.