Abstract
BACKGROUND: Obesity is a well-known risk factor for elevated inflammation and insulin resistance. Social anxiety may moderate this relationship, such that individuals who areboth obese and socially anxious may have an even greater risk for elevated inflammation and insulin resistance than those who are obese but not socially anxious; the combination of obesity and social anxiety is markedly stressful. METHODS: The current paper reports secondary analyses from the Biomarker wave of the Mid-Life in the United States (MIDUS) study (N = 1255), a publicly available dataset of American adults. Participants completed a standard scale measuring social anxiety symptoms and had their waist circumference, height, and weight measured by a staff member. They also provided a fasting blood sample that was assayed for CRP, IL-6, HOMA-IR, glucose, and insulin. RESULTS: The interaction between obesity and social anxiety symptoms was significant. People with a larger waist circumference and more social anxiety symptoms had greater inflammation and insulin resistance relative to those with a larger waist circumference but less social anxiety symptoms. These results were similar for both measures of inflammation and were robust across both the unadjusted and adjusted models. The results were also largely replicated in models using body mass index (BMI) rather than waist circumference as the measure of obesity. CONCLUSIONS: The current findings build on existing work about the health risks of obesity, extending it in an important new direction by demonstrating that these health risks are stronger among those who are also socially anxious. In fact, the magnitude of the relationship between obesity and metabolic function is 1.5 times stronger among those with more social anxiety symptoms. Thus, knowing whether a person is obese only provides one piece of the puzzle; knowing information about both obesity and social anxiety symptoms is critical for understanding who is most at risk for obesity-related health problems. Thus, a critical next step is for intervention scientists to examine health programs tailored to people who are both obese and socially anxious.