Trajectories of body mass index among active-duty U.S. Army soldiers, 2011-2014

Weight management behaviours mediate the relationship between weight cycling, BMI and diet quality among US Army Soldiers

Weight cycling is prevalent in sports/professions with body composition standards, and has been associated with weight management behaviours that may contribute to suboptimal diet quality and weight gain. US Army Soldiers may be at increased risk of weight cycling relative to civilians due to mandated body composition standards. However, the relationship between weight cycling, weight management behaviours, BMI and diet quality among Soldiers is unknown. In this cross-sectional study, 575 Soldiers (89 % enlisted, 90 % male, 23 ± 4 years) at Army installations at Joint Base Elmendorf-Richardson, AK, Joint-Base Lewis McChord, WA, and Fort Campbell, KY completed questionnaires on food frequency, health-related behaviours and history of weight cycling (≥ 3 weight fluctuations ≥ 5 % body weight). Weight cycling was reported by 33 % of Soldiers. Those who reported weight cycling reported higher BMI (27 ± 4 v. 25 ± 3 kg/m², P < 0·001) and higher prevalence of engaging in weight management behaviours prior to body weight screening but did not report lower dietary quality (Healthy Eating Index-2015 (HEI) scores 59 ± 10 v 59 ± 11, P = 0·46) relative to those who did not report weight cycling. Results of mediation analyses suggested that weight cycling may affect BMI both directly (c' = 1·19, 95 % CI: 0·62, 1·75) and indirectly (ab = 0·45, 95 % CI: 0·19, 0·75), and HEI scores indirectly (ab = 0·69, 95 % CI: 0·20, 1·35) through the adoption of weight management behaviours. Weight cycling is common in Soldiers and is associated with higher BMI and higher prevalence of engaging in weight management behaviours that mediate associations between weight cycling, BMI and diet quality.

Group‐based trajectory modeling of body mass index and body size over the life course: A scoping review

Background

Group‐based trajectory modeling has been applied to identify distinct trajectories of growth across the life course. Objectives of this study were to describe the methodological approaches for group‐based modeling of growth across the life course and to summarize outcomes across studies.

Methods

A scoping review with a systematic search of Medline, EMBASE, CINAL, and Web of Science was conducted. Studies that used a group‐based procedure to identify trajectories on any statistical software were included. Data were extracted on trajectory methodology, measures of growth, and association with outcomes.

Results

A total of 59 studies were included, and most were published from 2013 to 2020. Body mass index was the most common measure of growth (n = 43). The median number of identified trajectories was 4 (range: 2–9). PROC TRAJ in SAS was used by 33 studies, other procedures used include TRAJ in STATA, lcmm in R, and Mplus. Most studies evaluated associations between growth trajectories and chronic disease outcomes (n = 22).

Conclusions

Group‐based trajectory modeling of growth in adults is emerging in epidemiologic research, with four distinct trajectories observed somewhat consistently from all studies. Understanding life course growth trajectories may provide further insight for population health interventions.

Body weight status, perceived stress, and emotional eating among US Army Soldiers: A mediator model

BACKGROUND

In civilians, overweight and obesity are associated with emotional eating behaviors such as eating in response to stress, but this association has not been examined in Soldiers, a population with unique stressors. This cross-sectional study examined the relationship between perceived stress (PS), emotional eating (EE), and outcomes of body mass index (BMI), and failing Army body composition (BC) standards among Soldiers.

METHODS

Soldiers (N = 1460, 83% male, 23.5 ± 5.2 years old) completed validated surveys on PS, EE, and adherence with military BC standards. Conditional process models and mediation models tested gender as a moderator and EE as a mediator of associations between PS and BMI and PS and BC failure, respectively.

RESULTS

Higher PS was associated with more frequent self-reported EE behaviors (p < 0.001), higher BMI (p < 0.001), and BC failure (p < 0.001). BMI significantly increased with frequency of reported EE behaviors (p < 0.001). Gender was not a statistically significant moderator in the relationship between PS, EE, and, BMI (p = 0.83) or BC failure (p = 0.57). PS appears to affect BMI indirectly through EE behaviors (c' = 0.03, 95% CI: 0.02, 0.04). PS may affect BC failure directly (c' = 1.04, 95% CI: 1.01, 1.08) and indirectly (ab = 1.02, 95% CI: 1.01, 1.03) through EE as a mediator.

CONCLUSIONS

EE behaviors may mediate the positive association between PS, BMI, and BC failure. Prospective investigation is warranted to better understand the role of EE in health-related outcomes among Soldiers and populations in high stress professions.