Background- MEDOW is an 18-month randomised trial comparing effects of a low fat versus a monounsaturated fatty acid (MUFA)-enriched diet (35-40%E as fat, mainly from macadamia nuts) on cardiometabolic (CM) health indicators (body weight, lipidaemia, endothelial function and glycaemia). These diets plus physical activity (PA) plans according to Australian National PA Guidelines will be given to 60 overweight/obese, but otherwise healthy adults. Intrinsic Motivation Theory will be used as a guiding framework to identify themes related to program adherence and CM outcomes. Objectives- To describe characteristics of volunteers for inclusion in the MEDOW trial, and to summarise baseline CM characteristics of the subpopulation accepted into the trial. Design- Cross-sectional; Respondents to local newspaper ads for volunteers in a weight loss study. Outcomes- Of 116 volunteers expressing interest to date, 29 (25%) met inclusion criteria for the study, and consented to participate. Their mean BMI was 35.2 (range 27.5-43.5), with 48% and 52% being overweight and obese, respectively. Mean total, HDL and LDL cholesterol levels were 5.2 (range 4.1-6.7), 1.5 (range 0.9-2.6) and 3.1 (range 2.0-4.8) mmol/L, respectively. Baseline levels of C-reactive protein, IL-6 and Lp(a) were also taken. Of those excluded (n=87), 8 (no reason given) and 9 (personal reasons) dropped out before screening. The most common reason for screening out (27%) was the presence of a medical condition requiring medication (hypertension, glucose intolerance, hypercholesterolaemia, arthritis, depression, and diabetes). Several volunteers had personal contact with included subjects, which compromised randomisation. Food sensitivities and fish oil supplementation also were common reasons for exclusion. Conclusions- Volunteers screened out of clinical trials are a rich, but underutilised, source of information on enhancing reach and effectiveness of community-based lifestyle interventions. These data indicate a range of sub-populations of overweight subjects, with differing health risk profiles, often requiring tailored interventions.