Geoff D.C. Ball

Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults: A Meta-analysis

IMPORTANCE Many claims have been made regarding the superiority of one diet or another for inducing weight loss. Which diet is best remains unclear. OBJECTIVE To determine weight loss outcomes for popular diets based on diet class (macronutrient composition) and named diet. DATA SOURCES Search of 6 electronic databases: AMED, CDSR, CENTRAL, CINAHL, EMBASE, and MEDLINE from inception of each database to April 2014. STUDY SELECTION Overweight or obese adults (body mass index ≥25) randomized to a popular self-administered named diet and reporting weight or body mass index data at 3-month follow-up or longer. DATA EXTRACTION AND SYNTHESIS Two reviewers independently extracted data on populations, interventions, outcomes, risk of bias, and quality of evidence. A Bayesian framework was used to perform a series of random-effects network meta-analyses with meta-regression to estimate the relative effectiveness of diet classes and programs for change in weight and body mass index from baseline. Our analyses adjusted for behavioral support and exercise. MAIN OUTCOMES AND MEASURES Weight loss and body mass index at 6- and 12-month follow-up (±3 months for both periods). RESULTS Among 59 eligible articles reporting 48 unique randomized trials (including 7286 individuals) and compared with no diet, the largest weight loss was associated with low-carbohydrate diets (8.73 kg [95% credible interval {CI}, 7.27 to 10.20 kg] at 6-month follow-up and 7.25 kg [95% CI, 5.33 to 9.25 kg] at 12-month follow-up) and low-fat diets (7.99 kg [95% CI, 6.01 to 9.92 kg] at 6-month follow-up and 7.27 kg [95% CI, 5.26 to 9.34 kg] at 12-month follow-up). Weight loss differences between individual diets were minimal. For example, the Atkins diet resulted in a 1.71 kg greater weight loss than the Zone diet at 6-month follow-up. Between 6- and 12-month follow-up, the influence of behavioral support (3.23 kg [95% CI, 2.23 to 4.23 kg] at 6-month follow-up vs 1.08 kg [95% CI, -1.82 to 3.96 kg] at 12-month follow-up) and exercise (0.64 kg [95% CI, -0.35 to 1.66 kg] vs 2.13 kg [95% CI, 0.43 to 3.85 kg], respectively) on weight loss differed. CONCLUSIONS AND RELEVANCE Significant weight loss was observed with any low-carbohydrate or low-fat diet. Weight loss differences between individual named diets were small. This supports the practice of recommending any diet that a patient will adhere to in order to lose weight.

Systematic review of knowledge translation strategies in the allied health professions

BackgroundKnowledge translation (KT) aims to close the research-practice gap in order to realize and maximize the benefits of research within the practice setting. Previous studies have investigated KT strategies in nursing and medicine; however, the present study is the first systematic review of the effectiveness of a variety of KT interventions in five allied health disciplines: dietetics, occupational therapy, pharmacy, physiotherapy, and speech-language pathology.MethodsA health research librarian developed and implemented search strategies in eight electronic databases (MEDLINE, CINAHL, ERIC, PASCAL, EMBASE, IPA, Scopus, CENTRAL) using language (English) and date restrictions (1985 to March 2010). Other relevant sources were manually searched. Two reviewers independently screened the titles and abstracts, reviewed full-text articles, performed data extraction, and performed quality assessment. Within each profession, evidence tables were created, grouping and analyzing data by research design, KT strategy, targeted behaviour, and primary outcome. The published descriptions of the KT interventions were compared to the Workgroup for Intervention Development and Evaluation Research (WIDER) Recommendations to Improve the Reporting of the Content of Behaviour Change Interventions.ResultsA total of 2,638 articles were located and the titles and abstracts were screened. Of those, 1,172 full-text articles were reviewed and subsequently 32 studies were included in the systematic review. A variety of single (n = 15) and multiple (n = 17) KT interventions were identified, with educational meetings being the predominant KT strategy (n = 11). The majority of primary outcomes were identified as professional/process outcomes (n = 25); however, patient outcomes (n = 4), economic outcomes (n = 2), and multiple primary outcomes (n = 1) were also represented. Generally, the studies were of low methodological quality. Outcome reporting bias was common and precluded clear determination of intervention effectiveness. In the majority of studies, the interventions demonstrated mixed effects on primary outcomes, and only four studies demonstrated statistically significant, positive effects on primary outcomes. None of the studies satisfied the four WIDER Recommendations.ConclusionsAcross five allied health professions, equivocal results, low methodological quality, and outcome reporting bias limited our ability to recommend one KT strategy over another. Further research employing the WIDER Recommendations is needed to inform the development and implementation of effective KT interventions in allied health.

Vigorous physical activity and longitudinal associations with cardiometabolic risk factors in youth.

Objective:To examine the longitudinal associations between different physical activity (PA) intensities and cardiometabolic risk factors among a sample of Canadian youth.Methods:The findings are based on a 2-year prospective cohort study in a convenience sample of 315 youth aged 9–15 years at baseline from rural and urban schools in Alberta, Canada. Different intensities (light, moderate and vigorous) of PA were objectively assessed with Actical accelerometers. The main outcome measures were body mass index (BMI) z-score, waist circumference, cardiorespiratory fitness and systolic blood pressure at 2-year-follow-up and conditional BMI z-score velocity. A series of linear regression models were conducted to investigate the associations after adjusting for potential confounders.Results:At follow-up, cardiorespiratory fitness increased (quartile 1 vs quartile 4=43.3 vs 50.2; Ptrend<0.01) and waist circumference decreased (quartile 1 vs quartile 4=79.0 vs 72.6; Ptrend=0.04; boys only) in a dose-response manner across quartiles of baseline vigorous-intensity PA. A similar trend was observed for systolic blood pressure (quartile 1 vs quartile 4=121.8 vs 115.3; Ptrend=0.07; boys only). Compared with quartile 1 of vigorous-intensity PA, BMI z-score at follow-up and conditional BMI z-score velocity were significantly lower in the quartile 2 and 3 (P<0.05). Waist circumference at follow-up also decreased (quartile 1 vs quartile 4=75.3 vs 73.8; Ptrend=0.04) across quartiles of baseline moderate-intensity PA.Conclusions:Time spent in vigorous-intensity PA was associated with several positive health outcomes 2 years later. These findings suggest that high-intensity activities in youth help to reduce the risk for several chronic diseases.

Predictors of Metabolically Healthy Obesity in Children

OBJECTIVE To determine the prevalence of metabolically healthy obesity (MHO) in children and examine the demographic, adiposity, and lifestyle predictors of MHO status. RESEARCH DESIGN AND METHODS This cross-sectional study included 8–17 year olds with a BMI ≥85th percentile who were enrolled in a multidisciplinary pediatric weight management clinic from 2005–2010. Demographic, anthropometric, lifestyle, and cardiometabolic data were retrieved by retrospective medical record review. Participants were dichotomized as either MHO or metabolically unhealthy obese (MUO) according to two separate classification systems based on: 1) insulin resistance (IR) and 2) cardiometabolic risk (CR) factors (blood pressure, serum lipids, and glucose). Multivariable logistic regression was used to determine predictors of MHO using odds ratios (ORs) with 95% CIs. RESULTS The prevalence of MHO-IR was 31.5% (n = 57 of 181) and MHO-CR was 21.5% (n = 39 of 181). Waist circumference (OR 0.33 [95% CI 0.18–0.59]; P = 0.0002) and dietary fat intake (OR 0.56 [95% CI 0.31–0.95]; P = 0.04) were independent predictors of MHO-IR; moderate-to-vigorous physical activity (OR 1.80 [95% CI 1.24–2.62]; P = 0.002) was the strongest independent predictor of MHO-CR. CONCLUSIONS Up to one in three children with obesity can be classified as MHO. Depending on the definition, adiposity and lifestyle behaviors both play important roles in predicting MHO status. These findings can inform for whom health services for managing pediatric obesity should be prioritized, especially in circumstances when boys and girls present with CR factors.

Physical activity intensity and cardiometabolic risk in youth.

OBJECTIVE To determine the association between physical activity (PA) intensities and cardiometabolic risk factors in youth. DESIGN Cross-sectional study using data from the 2008 Healthy Hearts Prospective Cohort Study of Physical Activity and Cardiometabolic Health in Youth. SETTING Rural and urban communities in Alberta, Canada. PARTICIPANTS A convenience sample of 605 youth aged 9 to 17 years. Youth were on average aged 12.1 years, 248 were boys (41%), and 157 were overweight or obese (26%). MAIN EXPOSURE Actical accelerometer-measured PA intensity. MAIN OUTCOMES MEASURES The primary outcome was body mass index (calculated as weight in kilograms divided by height in meters squared) z score. Secondary outcome measures included waist circumference, systolic blood pressure, and cardiorespiratory fitness (maximal oxygen consumption [[Vdot]O2max]). RESULTS Body mass index z score, waist circumference, and systolic blood pressure decreased and [Vdot]O2max increased in a dose-response manner across tertiles of vigorous PA (adjusted P < .001). No significant differences in cardiometabolic risk factors were seen across tertiles of moderate or light PA in multivariable analyses. Achieving more than 7 minutes of vigorous PA daily was associated with a reduced adjusted odds ratio of overweight status (0.56; 95% CI, 0.33-0.95) and elevated systolic blood pressure (0.36; 95% CI, 0.16-0.79). The odds of overweight status and elevated blood pressure decreased with increasing time and intensity of PA. CONCLUSIONS Only vigorous PA was consistently associated with lower levels of waist circumference, body mass index z score, systolic blood pressure, and increased cardiorespiratory fitness in youth. These findings underscore the importance of vigorous PA in guidelines for children and adolescents.

Neighborhood physical activity opportunities for inner-city children and youth

The purpose of this study was to assess perceived physical activity (PA) opportunities and barriers for inner-city youth. Data were collected via interviews with 59 children, 8 school staff, and 13 youth workers plus objective neighborhood data. Analyses revealed three themes that influenced PA: neighborhood characteristics, family involvement, and adult-supervised programs. The neighborhood was highly walkable and multiple play spaces were available, but safety concerns restricted access. Children were rarely allowed out alone, but family accompaniment facilitated PA. Organized programs provided adult-supervised PA, but programs faced staffing problems that served to limit the provision of PA opportunities. Multiple ecological factors constrain or enable PA among inner-city youth.

Metabolic Risk Varies According to Waist Circumference Measurement Site in Overweight Boys and Girls

OBJECTIVES To compare waist circumference (WC) values measured at 4 commonly recommended sites and examine the relationships between WC sites and markers of metabolic risk in a sample of overweight boys and girls referred for weight management. STUDY DESIGN Overweight (mean body mass index percentile, 98.7; SD, 1.0) children and adolescents (n = 73; 41 girls, 32 boys; mean age, 12.5 years; SD, 2.6 years) had WC measured at 4 sites: iliac crest (WC1), narrowest waist (WC2), midpoint between the floating rib and iliac crest (WC3), and umbilicus (WC4). Height, weight, fasting insulin level, glucose level, cholesterol level, and systolic and diastolic blood pressure were also measured. RESULTS Overall, WC1 (108.5 cm; SD, 16.3 cm) was greater than WC2 (97.4 cm; SD, 13.6 cm; P < .003), and WC2 was smaller than WC3 (104.3 cm; SD, 15.3 cm; P = .02) and WC4 (108.7 cm; SD, 16.2 cm; P < .0003). With logistic regression, WC2 and WC3 were revealed to be more consistently associated with metabolic syndrome by using 3 different definitions. CONCLUSION In our sample, we observed differences in 4 commonly recommended WC measurement sites and found that all sites were not equivalently associated with metabolic risk. Our findings provide preliminary support suggesting that WC measured at the narrowest waist and midpoint between the floating rib and iliac crest may represent the measurement sites most closely associated with metabolic risk in overweight boys and girls.

Prevalence Estimates of Overweight and Obesity in Cree Preschool Children in Northern Quebec According to International and US Reference Criteria

OBJECTIVES We estimated the prevalence of overweight and obesity in Cree Canadian children aged 5 years (n=1044) using international and US growth references and examined the longitudinal tracking of weight categories between ages 2 and 5 years (n=562). METHODS Weight categories based on body mass index (calculated from measured heights and weights) were derived from the International Obesity Task Force (IOTF) and the Centers for Disease Control and Prevention (CDC) references. RESULTS According to the IOTF reference, 52.9% of children were overweight (31.6%) or obese (21.3%) whereas with the CDC reference, 64.9% were overweight (27.5%) or obese (37.4%). The IOTF and CDC references provided dissimilar tracking of weight categories. Based on the IOTF reference, 4.9% of the children who were normal weight at age 2 years were obese at age 5 years. Based on the CDC reference, 14.9% of children categorized as normal weight at age 2 years were obese at age 5 years. CONCLUSIONS The IOTF reference provided more conservative estimates of obesity than the CDC reference, and longitudinal analyses showed dissimilar tracking of weight categories with the 2 references. Public health responses to obesity prevalence estimates should be made with awareness of methodological limitations.

Obesity negatively impacts lung function in children and adolescents.

To investigate the relationship between weight status (body mass index [BMI] percentile and BMI z‐score) and lung volumes in healthy children and adolescents.

Physical education and sport programs at an inner city school: exploring possibilities for positive youth development

Background: School-based recreational opportunities for youth from low-income inner-city neighbourhoods are often lacking. School programs represent an ideal location for promoting youth development in low-income areas because they can provide safe, supervised, and structured activities. Such activities should include not only physical education (PE) programs, but other extra-curricular activities such as intramural sports and school sport teams. Because we were interested in how these programs were associated with youth development, we used the concept of positive youth development (PYD) to guide this study. Purpose: This case study examined school staff members’ and childrens perceptions of school PE, intramural sports, and sport teams with a view to establish factors that facilitated or impeded PYD. Method: Data were collected via individual interviews with eight teachers and 59 children from an inner-city school that had a mission to promote positive behaviors consistent with PYD. Interviews were transcribed verbatim and subjected to a categorical aggregation analysis procedure. Results: Findings showed factors that facilitated or impeded PYD varied across different contexts. In PE, the importance of a specialist PE teacher and establishing clear boundaries during lessons while providing children with perceptions of choice were important. Children enjoyed intramural sports, but there were few attempts to create an appropriate developmental atmosphere during these sessions. In fact, intramural sports were associated with negative student interactions. Coaches of the sport teams used techniques to promote social interactions and respect. Most notable student outcomes associated with PYD related to fostering empathy and social connections. Conclusion: These findings showed differences in contextual factors across the PE/sport programs that helped promote or impeded PYD. These differences revealed some practical suggestions for promoting PYD, which include focusing on the developmental orientation of PE classes, the fun of intramurals, and the ‘life skills’ focus of the sport teams. Furthermore, we suggest an integrated, school-wide approach is required to help promote PYD.