Fluctuating asymmetry (FA) in adults is thought to reflect specific types of developmental stress. If true, adult FA may be a proxy for developmental stress in past as well as current populations. To date, studies of the link between development and adult FA have produced ambiguous results due to insufficient measurement data for childhood environments. This study seeks to overcome this limitation using a structural equation modeling approach to evaluate the relationship between 29 measures of developmental environments and precise measures of adult FA. Sociodemographic information and 3D facial photographs were collected from 80 adult New Mexicans. Facial FA was measured from the photographs using geometric morphometric analysis of 12 facial landmarks. Each participant responded to a questionnaire addressing the developmental environment, including childhood home environment, family SES, health, and dietary quality. We used structural equation models to examine predictive relationships between latent variables constructed from questionnaire responses and adult facial FA. Childhood dietary quality was negatively associated with adult FA scores, meaning that poorer diets predict higher FA (standardized path coefficient -0.174, p = 0.039). Factors that loaded positively on the dietary quality construct were a diet quality index, the frequency of homemade meals, and the frequency of homemade breakfast, while the frequency of fast-food meals loaded negatively. No other latent variable predicted adult facial FA. We posit that the negative relationship between dietary quality and FA reflects a negative energy balance experienced during development. Insufficient nutrition results in a reduced capacity to buffer against environmental perturbations, with increased FA as evidence. Given previously established links between FA and adult health outcomes in humans, this finding also underscores the importance of dietary quality during development for ensuring health and wellbeing later in life. These results indicate that FA in facial shape may signal the relative quality of dietary conditions during development.