This study was performed to explore whether the relationship between Med–diet intake and markers of insulin resistance and inflammation are mediated by body mass index (BMI) or waist circumference (WC) in a representative US population. These outcomes propose that decreasing abdominal obesity may play an imperative role in the pathway through which Med–diet intake decreases insulin resistance and inflammation.

Methods

• For this study, they utilized a cross–sectional information from 4700 adults aged 20–90 y.
• Participants without any previous diagnosis of cancer, cardiovascular disease, diabetes, or hypertension based on the NHANES III, 1988–1994 were enrolled in this study.
• A Med–diet score (MDS) was created to evaluate adherence to the Med–diet. Linear regression models were fitted in conventional and causal mediation analyses comparing extreme MDS tertiles.

Results

• Compared with the lowest MDS tertile, the highest tertile of MDS was related to a 0.77 lower BMI (in kg/m²; P = 0.004) and a 2.7 cm lower WC (P < 0.001) after multivariable adjustment.
• WC mediated the relationship of MDS with insulin resistance and glucose intolerance markers (log insulin, log homoeostasis model evaluation of insulin resistance, fasting glucose, and glycated hemoglobin) and inflammatory markers (white blood cell count and fibrinogen), whereas BMI mediated the relationship between MDS and insulin resistance and glucose intolerance markers only (all P < 0.05).
• They found the mediated impacts of WC were consistently greater than those of BMI for all markers in both conventional and causal mediation investigations.
• Besides, the relationship between MDS and fasting glucose was fully mediated by adiposity, especially by WC in men aged <45 y and in premenopausal women.

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