Worldwide, 1.6 billion adults are overweight and 400 million are obese. For older adults, being in these categories exacerbates multiple chronic diseases and leads to frailty. The aim of this study was to explore the knowledge of older adults in Ireland and the USA about their body mass index (BMI) category and motivation to change. A quantitative descriptive research design was used in the study. Two convenience samples of community-dwelling older adults, one in Ireland (n=70) and one in the USA (n=70) participated in the study. Data was collected in the form of questionnaires and BMI was calculated. This study found that fewer Irish participants knew their BMI category. In both groups, measured BMI differed greatly from self-perceived BMI. These findings suggest that older adults are unaware of their weight status and therefore do not know that they are in a BMI category with multiple health consequences.