Globalization is transforming food systems around the world. With few geographical areas spared from nutritional, dietary and epidemiological transitions, chronic diseases have reached pandemic proportions. A question therefore arises as to the sustainability of local food systems. The overall purpose of this article is to put in perspective how local food systems respond to globalization through the assessment of five different case studies stemming from an international research network of Human-Environment Observatories (OHM), namely Nunavik (Québec, Canada), Oyapock (French Guiana, France), Estarreja (Portugal), Téssékéré (Senegal) and Littoral-Caraïbes (Guadeloupe, France). Each region retains aspects of its traditional food system, albeit under different patterns of influence modelled by various factors. These include history, cultural practices, remoteness and accessibility to and integration of globalized ultra-processed foods that induce differential health impacts. Furthermore, increases in the threat of environmental contamination can undermine the benefits of locally sourced foods for the profit of ultra-processed foods. These case studies demonstrate that: (i) the influence of globalization on food systems can be properly understood by integrating sociohistorical trajectories, socioeconomic and sociocultural context, ongoing local environmental issues and health determinants; and (ii) long-term and transverse monitoring is essential to understand the sustainability of local food systems vis-à-vis globalization.