This paper explores two different aspects of food security, namely undernourishment and overweight in the two Caribbean Islands of Jamaica and St. Lucia. The analysis draws on household surveys conducted in late 2006 and early 2007 among 729 St. Lucian and 1009 Jamaican households. Combining qualitative and quantitative methods, the paper focuses on the main vulnerable livelihoods on the two islands, including subsistent farmers and farm labourers, city dwellers, hotel workers and fisher folks. Exposure to risk is an important determinant of food insecurity. Shocks of relevance to vulnerable groups in the two islands include both household specific shocks such of illness, but more importantly also community level shocks such as natural disasters in form of droughts, storms and floods. Natural disasters are of particular importance to these livelihoods and changes in the frequency and severity of such shocks, e.g. as a consequence of changing climate may lead to increased food insecurity. At the same time, it is generally acknowledged that the food systems and the very nature of the food security problem in the Caribbean countries are gradually changing, with food availability becoming less of an issue in most of the region. Instead, energy intensive and unbalanced diets leading to overweight and obesity is increasingly becoming the key food security challenge, even so among households considered vulnerable of becoming food insecure. This is confirmed by the study, looking at anthropometric data collected from the participating households.