Background

Social disadvantage is clearly associated with obesity, but little is known about how it impacts weight trajectories over time.This longitudinal analysis examines food insecurity among children in a multidisciplinary obesity clinic.

Methods

Between 2008-2016, 463 patients (1,222 visits) had household food security assessed using a 6-item questionnaire. A mixed effects approach was used to model change in BMI z-score over time. Random effects were set to the individual child. Fixed effects included the following time-invariant factors: gender, race/ethnicity, starting age, income (4 categories) and food security.Visit number (collapsed to 6 categories: 1, 2, 3, 4- 5, 6-8, and 9+ visits) and elapsed time since the initial visit were time-variant variables. Lastly, we tested interactions between visit number and race/ethnicity, age, sex, income, and food insecurity to examine their influence on weight status over time.

Results

In the fully-adjusted model, average BMI z-score (intercept) was 2.87 (sd 0.45). Baseline BMI z-scores were higher among Non-Hispanic Blacks (compared to Whites), and lower for older children.Elapsed time, number of visits, and being Non-Hispanic Asian were associated with decreasing BMI z-score, whereas child’s age was associated with increasing z-score. While lower income levels predisposed to increasing BMI z-score, this relationship was not significant once food security was included in the model.A total of 31% of the sample was food-insecure; a significant interaction showed that over successive visits, food insecurity was independently associated with increasing BMI z-score (+0.02, 95% CI [0.01, 0.04], p=0.01).

Conclusions

Household food insecurity is associated with a less optimal weight trajectory for children in weight management. This may be because insecure food access complicates efforts to improve nutritional quality, and efforts to address food access may lead to greater success.