Predictors of racial differences in weight loss: the PROPEL trial

OBJECTIVE

Studies have consistently shown that African American individuals lose less weight in response to behavioral interventions, but the mechanisms leading to this result have been understudied.

METHODS

Data were derived from the PROmoting Successful Weight Loss in Primary CarE in Louisiana (PROPEL) study, which was a cluster-randomized, two-arm trial conducted in primary care clinics. In the PROPEL trial, African American individuals lost less weight compared with patients who belonged to other racial groups after 24 months. In the current study, counterfactual mediation analyses among 445 patients in the intervention arm of PROPEL were used to determine which variables mediated the relationship between race and weight loss. The mediators included treatment engagement, psychosocial, and lifestyle factors.

RESULTS

At 6 months, daily weighing mediated 33% (p = 0.008) of the racial differences in weight loss. At 24 months, session attendance and daily weighing mediated 35% (p = 0.027) and 66% (p = 0.005) of the racial differences in weight loss, respectively. None of the psychosocial or lifestyle variables mediated the race-weight loss association.

CONCLUSIONS

Strategies specifically targeting engagement, such as improving session attendance and self-weighing behaviors, among African American individuals are needed to support more equitable weight losses over extended time periods.

Impact of the built, social, and food environment on long-term weight loss within a behavioral weight loss intervention

Background

Behavioral weight loss interventions can lead to an average weight loss of 5%-10% of initial body weight, however there is wide individual variability in treatment response. Although built, social, and community food environments can have potential direct and indirect influences on body weight (through their influence on physical activity and energy intake), these environmental factors are rarely considered as predictors of variation in weight loss.

Objective

Evaluate the association between built, social, and community food environments and changes in weight, moderate-to-vigorous physical activity (MVPA), and dietary intake among adults who completed an 18-month behavioral weight loss intervention.

Methods

Participants included 93 adults (mean ± SD; 41.5 ± 8.3 years, 34.4 ± 4.2 kg/m2, 82% female, 75% white). Environmental variables included urbanicity, walkability, crime, Neighborhood Deprivation Index (includes 13 social economic status factors), and density of convenience stores, grocery stores, and limited-service restaurants at the tract level. Linear regressions examined associations between environment and changes in body weight, waist circumference (WC), MVPA (SenseWear device), and dietary intake (3-day diet records) from baseline to 18 months.

Results

Grocery store density was inversely associated with change in weight (β = -0.95; p = 0.02; R 2 = 0.062) and WC (β = -1.23; p < 0.01; R 2 = 0.109). Participants living in tracts with lower walkability demonstrated lower baseline MVPA and greater increases in MVPA versus participants with higher walkability (interaction p = 0.03). Participants living in tracts with the most deprivation demonstrated greater increases in average daily steps (β = 2048.27; p = 0.02; R 2 = 0.039) versus participants with the least deprivation. Limited-service restaurant density was associated with change in % protein intake (β = 0.39; p = 0.046; R 2 = 0.051).

Conclusion

Environmental factors accounted for some of the variability (<11%) in response to a behavioral weight loss intervention. Grocery store density was positively associated with weight loss at 18 months. Additional studies and/or pooled analyses, encompassing greater environmental variation, are required to further evaluate whether environment contributes to weight loss variability.

Early Nonfood Parent-Infant Interactions and Development of Obesity in a High-Risk, Diverse Sample

OBJECTIVE

This study aimed to understand the protective role of positive mother-infant interactions in the context of food and nonfood behaviors against obesity risk later in life among a cohort of low-income children at high prenatal risk due to maternal substance use during pregnancy.

METHODS

The sample consisted of 216 mother-infant dyads (49% boys) participating in an ongoing longitudinal study. Mother-infant interactions during a feeding episode and a free-play task were measured at child age 1 and 7 months, respectively. Children's length/height and weight were measured at 1, 7, 13, 24, 36, and 48 months of age; at kindergarten age (approximately 60 months); and in second grade (approximately 84 months). BMI growth trajectories were modeled.

RESULTS

No significant associations were found between mother-child feeding interactions and child BMI trajectories. Maternal warmth (95% CI: -0.020 to -0.0005; P = 0.04) and child positive affect (95% CI: -0.020 to -0.002; P = 0.014) during free play were associated with a more normative child BMI trajectory.

CONCLUSIONS

Results from this study indicated that high maternal warmth and child positive affect during play, but not feeding interactions, are associated with reduced obesity risk from infancy to middle childhood in the context of high pre- and postnatal risks.

Coming unmoored: disproportionate increases in obesity prevalence among young, disadvantaged white women

OBJECTIVES

Since the 1980s, older, low-educated White women experienced an unprecedented decrease in life expectancy. We investigated whether a similar phenomenon was evident among younger women for obesity.

METHODS

Using the National Health and Nutrition Examination Survey, age-adjusted changes were estimated in the prevalence of overall and abdominal obesity (BMI ≥ 30 kg/m(2) , waist circumference > 88 cm) between 1988-1994 and 2003-2010 among non-Hispanic White women aged 25-44 years, stratified by educational attainment (<high school (HS), HS, some college, college degree). To address bias from secular increases in educational attainment, White women's changes in obesity prevalence were compared to changes among similarly educated Black women.

RESULTS

Relative increases in overall obesity were disproportionately larger for low-educated (<HS) compared to college-educated White women: 12.3 (95% CI: 3.1, 21.5) percentage points (ppts). For overall and abdominal obesity, general trends indicated dissimilar racial differences by educational attainment. For instance, overall obesity increased more in Blacks than Whites among college-educated (9.9 ppts) but not low-educated (-2.5 ppts) women.

CONCLUSIONS

Contemporary young, low-educated White women showed indications of disproportionate worsening of overall obesity prevalence compared to more educated White and similarly educated Black women. Low education levels are more powerful indicators of obesity risk among contemporary White women than 30 years ago.