Exploring the Influence of Diet Quality on Visceral Adiposity and Risk of Mortality from Non-communicable Diseases among Adults in the US

High visceral adipose tissue (VAT), more so than subcutaneous adipose tissue, is associated with an increased risk of chronic disease and mortality. Following a higher quality diet is associated with lower VAT, and a reduced risk of death from all-causes, CVD, and cancer. This dissertation further explored the relationships between patterns of eating, VAT, and mortality through three distinct studies. Exploration of the Healthy Eating Index-2015 (HEI-2015) scores among the Multiethnic Cohort (MEC) examined the association between HEI-2015 scores and risk of all-cause and cause-specific mortality. A pilot study was conducted to determine the effects of intermittent energy restriction combined with a Mediterranean diet (IER+MED) compared to an active comparator, a euenergetic Dietary Approaches to Stop Hypertension (DASH) diet, on VAT reduction among East Asian American adults. Assessing the association between Healthy Eating Index-2010 (HEI-2010) scores, VAT and overall adiposity among a multiethnic adult population constituted the third study. These studies were completed using observational and interventional designs. For the HEI-2015 study, the primary analysis was a survival analysis among MEC participants followed over a 17-22 y period. The IER+MED study was a randomized study where participants followed the prescribed diets over 12 weeks. The HEI-2010 study was cross-sectional and used DXA-based VAT. Among the MEC sample, comparing those with the highest quality diets to those with the lowest quality, the reduction in risk of mortality from all-cause, CVD, and cancer was 21%, 24%, and 20%, respectively, for men and 21%, 25%, and 16%, respectively, for women. Those following the IER+MED had significantly larger reductions in DXA-derived VAT and total fat mass (−22.6 ± 3.6 cm2 and −3.3 ± 0.4 kg, respectively) vs. DASH (−10.7 ± 3.5 cm2 and −1.6 ± 0.4 kg) (p = 0.02 and p = 0.005). For the HEI-2010 study, BMI, percent body fat, total body fat, trunk fat, insulin, and HOMA-IR were inversely related to HEI-2010 scores (all p values < 0.004). Findings from this dissertation support following a healthy dietary pattern is associated with lower VAT, and a reduced risk of mortality from all-causes, CVD, and cancer. In particular, IER+MED, may help to lower VAT and improve liver function