Fight or flight: The effect of heart rate reactivity on acute stress-induced food intake.

The 'fight-or-flight-reaction' describes the suppression of all irrelevant functions like food intake during the acute stress response. However, heart rate reactivity and food intake under acute stress has not been investigated. Therefore, the aim of this study was to investigate the effect of high and low heart rate reactivity on food intake following an acute laboratory stress paradigm in individuals with healthy weight. Fifty-six men and women with healthy weight (BMI: M = 21.82 ± 1.53 kg/m²) were categorized into high heart rate reactors (H-HRR) and low heart rate reactors (L-HRR). After the stress paradigm of the Trier Social Stress Test (TSST), total energy intake was measured in a standardized laboratory meal. H-HRR demonstrated a significantly lower appetite (z = -3.133, p≤ 0.01) and food intake (t(49.13) = 2.253, p≤ 0.05, d= 0.68) after the TSST compared to the L-HRR. No differences in the stress perception and cognitive appraisal could be found between the two reactor groups. These results suggest that the stress-induced heart rate reactivity might be a responsible factor in the stress-eating paradox. In view of the divergent results of stress-induced eating studies in laboratory setting with acute stressors, it is highly important to control the effect of the heart rate reactivity on food intake.