Physiological Correlates of Anxiety-Driven Binge Eating in a Naturalistic Setting

Abstract Binge-Eating Disorder (BED) is highly prevalent and frequently comorbid with anxiety, yet the real-time psychophysiological processes that translate anxiety into binge behavior remain unclear. This study therefore aimed to identify real-time physiological and contextual correlates of anxiety-driven binge eating in a naturalistic setting. We employed a 14-day longitudinal monitoring of 120 adults assigned to four groups: BED + GAD (n = 40), BED-only (n = 20), GAD-only (n = 20), and healthy controls (n = 40). Participants completed ecological momentary assessments (EMA; 0–100 scales) synchronized with continuous ambulatory ECG for heart-rate variability (HRV; RMSSD) and scheduled salivary cortisol; laboratory stress reactivity was also assessed with the Trier Social Stress Test (TSST). Multilevel models tested within-person effects of lagged anxiety, HRV, and cortisol on urge to binge, while multilevel logistic regression predicted binge episodes. Results showed that the BED + GAD group exhibited greater clinical severity, metabolic risk, and altered stress physiology (lower HRV recovery, p=.021; blunted cortisol AUCi, p=.002) versus other groups. Across the sample, higher lagged anxiety predicted a stronger subsequent urge to binge (γ = 0.25, p<.001), whereas higher HRV predicted lower urges (γ=−0.13, p=.031). Binge episodes were prospectively associated with higher pre-binge anxiety (OR = 1.38, p<.001), lower HRV (OR = 1.25, p=.008), reduced mobility (OR = 1.31, p=.002), and greater screen time (OR = 1.15, p=.023). A random-forest model achieved an AUC of 0.76, with anxiety, HRV, and location variance as top predictors. These effects were strongest in the BED + GAD group. In conclusion, anxiety-driven binge risk is characterized by a synergistic state of high anxiety and low vagal regulation in naturalistic contexts, amplified by behavioral withdrawal. HRV and digital mobility markers provide actionable, real-time signals for effective interventions to prevent binge episodes.