ABSTRACT
The current COVID-19 pandemic continues for over eleven months. Several nutritional and behavioural aspects have been associated with an increased inflammatory state, or oxidative stress, which could negatively affect the course of COVID-19. As research has shown, metabolic diseases, including obesity, or type 2 diabetes mellitus (T2DM), in which proper diet is especially important, increase the risk of the COVID-19 infection and can exacerbate its course. This should be taken into account particularly in the areas with high prevalence of obesity and T2DM, such as the Western countries. In our paper, we have briefly summarised the harmful and beneficial nutritional and behavioural aspects, essential during the COVID-19 pandemic, which are present in particular among patients suffering from obesity and T2DM.