Uncertainty in the relevant spatial context may drive heterogeneity in findings on the built environment and energy balance. To estimate the effect of this uncertainty, we conducted a sensitivity analysis defining intersection and business densities and counts within different buffer sizes and shapes on associations with self-reported walking and body mass index. Linear regression results indicated that the scale and shape of buffers influenced study results and may partly explain the inconsistent findings in the built environment and energy balance literature. •Findings in research on the built environment and energy balance are inconsistent.•Uncertainty on the context relevant to energy balance drives this inconsistency.•We constructed built environment measures of varying buffer sizes and shapes.•We modeled the effect of these measures on self-reported walking and BMI.•Effect sizes and statistical significance varied by buffer size and shape.