A food desert is an area with limited access to affordable and nutritious food. The metaphor is used in order to emphasise the structural and spatial aspects of food environments and health-related practices. Food deserts can be urban, suburban, or rural areas inhabited by lower income groups, therefore less attractive for food retailers and investors. In such areas, the diversity of food shops and products is limited to highly processed and low-quality products, like frozen meals, food with low nutrient and high energy density, and fast food restaurants. These areas are mostly lacking in fresh produce and product diversity. 

Limited access to healthy food is both spatial, financial, and social issue. Factors determining the vulnerability of low socioeconomic status groups comprise their limited mobility and limited time/monetary resources, as well as their health/food literacy and food habits – difficult to improve in obesogenic food environments. People living in food deserts are therefore at a higher risk of developing food-related diseases.  

The food desert term/metaphor has been criticized for its limited accuracy in communicating the intricacies of food system inadequacies. Its reductive understanding of food access, theoretical shallowness and over-focusing on geographical aspects fail to reflect the more complex and contextual nature of food-related inequalities, often rooted on social exclusion. 

When developing the food desert metaphor, the concepts of food oasis and food swamp were also devised. A food oasis is an area with easy access to healthy and good-quality food, as opposed to food deserts. Food swamps are areas with an abundance of unhealthy food outlets, easy access to energy-dense products, like fast-foods, snacks and desserts. Some studies show that food swamp environments can predict public health community determinants (e.g. obesity rate) better than food deserts (Cooksey-Stowers et al., 2017) . 

Although food oases and food swamps share their theoretical flaws with the food desert term, in some studies they have been used to indicate complexity and multi-factor aspects of food environments. For instance, they help to point out that low-income areas can be food deserts as well as food oases (Howlett et. al, 2016), and they may problematize the characteristics of obesogenic environments (Ooksey-Stowers et al., 2017). As a basis for standardized research tools, the concept can be used to hypothesize the role of particular factors in food practices and health conditions.