The design and rationale of a multi-center randomized clinical trial comparing one avocado per day to usual diet: The Habitual Diet and Avocado Trial (HAT)

Excess visceral adiposity is associated with increased risk of diabetes and cardiovascular disease. In the U.S. approximately 60% of adults have visceral obesity. Despite high calorie and fat, small, well-controlled clinical studies suggest that avocado consumption has favorable effects on body weight and visceral adiposity. Additionally, short-term studies also suggest that consuming avocados increases satiety, hence, may decrease overall energy intake. The Habitual Diet and Avocado Trial HAT is a multi-center, randomized, controlled trial designed to test whether in a large, diverse cohort providing one avocado per day for consumption for six months compared to a habitual diet essentially devoid of avocados, will result in a decrease in visceral adiposity as measured by magnetic resonance imaging (MRI) in individuals with an increased waist circumference (WC). Additional outcome measures include hepatic lipid content, plasma lipid profiles, blood pressure and high sensitivity C-reactive protein. Inclusion criteria were increased WC and not currently eating more than two avocados per month. Major exclusion criteria were not eating or being allergic to avocados, and not willing or able to undergo MRI scans. From June 27, 2018 to March 4, 2020, 1008 participants were randomized at 4 clinics. The cohort was 72% women, 53% Non-Hispanic White, and had a mean age of 50 years. Follow-up was completed in October 2020 when 936 participants had final MRI scans. HAT will provide information on the effects of avocado consumption on visceral fat adiposity and cardiometabolic disease risk in a diverse sample of participants.