The association between psychological stress and obesity is well established, but the precise biological mechanisms underlying this relationship are unclear. This study by Brydon et al. sought to investigate the relationship between measures of adiposity and cytokines in responses to stress in a group of 67 healthy young women (18 to 25 years). Results showed that after the task inducing stress, plasma levels of interleukin-6 (IL-6) and leptin significantly increased (p<0.001) but plasma levels of interleukin-1 receptor antagonist (IL-1Ra) did not change. The increase in leptin from baseline to immediate post-stress was significantly associated with waist circumference, independent of age, ethnicity, smoking, and baseline leptin (r=0.35, p<0.01), while plasma levels of IL-1Ra were correlated with waist circumference (r=0.39, p<0.01). However, there was no significant association between IL-6 stress response and adiposity measures. Finally, the authors observed a relationship between abdominal obesity (waist circumference) and tertiles of inflammatory cytokine responses. In essence, people with larger cytokine responses had higher levels of abdominal fat. This study by Brydon et al. is significant in that it demonstrated an association between stress-induced inflammatory cytokine responses and abdominal obesity in women. In light of these findings, increased cytokine production could be a mechanism linking stress and abdominal obesity.
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