The global community is faced with one of the most challenging issues in recent times—food insecurity. Food insecurity (FI) is experienced in almost all regions of the world, especially in Asia and Africa, as more than 50% (425 million) of the people in the world affected by hunger in 2021 were in Asia and more than one third (278 million) lived in Africa [1]. About 12% of the world’s population was affected by severe FI, while more than 2 billion people were either moderately or severely food insecure in 2021 [1].

According to the 2023 Global Report on Food Crises, more than one quarter of a billion people are experiencing acute levels of hunger, while some are on the verge of extreme deprivation of food [2]. Increases in conflict events, rising poverty, escalating inequalities, widespread underdevelopment, climate crises, and the COVID-19 pandemic have also contributed to the worsening of global food insecurity [2]. It is worth noting that Africa (especially sub-Saharan Africa) is experiencing worsening FI, which is reflected in the inclusion of six African countries (Sierra Leone 40.5/100, Madagascar 40.6/100, Burundi 40.6/100, Nigeria 42/100, Sudan 42.8/100, and the Congo Dem. Rep. 43/100) among the top 10 bottom-ranking countries with the lowest Global Food Security Index (GFSI) score in the 2022 overall food security environment. No African countries were among the top 10 high-ranking countries [3]. According to the Food and Agriculture Organization (FAO) and its partners’ projections, the impact of the Russia–Ukraine war threatens food security globally. The ripple effect of the war will have numerous implications for global agricultural markets, and this can potentially worsen the state of food and nutrition security for many nations in the coming years [1].

Food insecurity and hunger are on the rise in Nigeria. In January 2023, the United Children Fund (UNICEF) projected that 25 million Nigerians are at risk of experiencing hunger by the third quarter of 2023. This revealed an increase of about 8 million in hunger from the 2022 estimates [4]. Nigeria ranked 107th out of 113 countries and 25th out of 28 sub-Saharan Africa (SSA) countries with a GFSI score of 42/100 in the GFSI 2022 [3,5]. Also, in the 2022 Global Hunger index (GHI), Nigeria ranked 103rd out of 121 countries, scoring 27.3/100. This indicates a serious level of hunger and suggests that Nigeria is not on track to achieve the Sustainable Development Goal 2 (SDG2) target by 2030 [5,6].

X-raying the food security environment in Nigeria, as reported in the GFSI 2022 under the four pillars for food security (Figure 1), indicated that Nigeria had the lowest score (25/100) globally on the affordability category. In the availability category, Nigeria ranked 108th globally and 26th in the region. The report showed that the very weak performance score (39.5) was a result of the “very weak” (0–39.9) scores obtained in certain indicators, such as agricultural research and development (30.7/100), supply-chain infrastructure (23.9/100), sufficiency of supply (25.5/100), political and social barriers to access (31.6/100), and food security and access policy commitments (0/100) [3].

Food security (according to the United Nations definition) is referred to as “People having at all times, physical, social and economic access to sufficient, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life” [7]. The term “food insecurity” simply refers to the opposite of food security, where conditions of food security are not met, and it can be broadly conceptualized along a range from mild to severe [8]. The definition contains four widely established pillars of food security, namely: availability, accessibility, utilization, and stability. The four pillars are important in understanding food security at any level, such as regional, household, and individual levels [9,10,11,12,13,14,15].

Generally, conditions that expose people to FI and hunger include extreme poverty, unemployment, corruption, unstable food access, ill health, non-existent social protection programmes, and terrorism [8,14,15,16,17,18,19]. FI is not only experienced in developing nations, as developed nations are also affected. In Australia, for instance, over 2 million households were affected by severe FI in 2022 [20], while in the United States of America (USA), an estimated 14.8% of children resided in food-insecure households [8,21]. It is generally believed that FI risk is unevenly distributed. The most vulnerable groups, such as children, women, the elderly, and internally displaced people (IDPs), usually suffer higher levels of FI [8,19,22,23,24,25]. FI may be momentary in nature, given the possibility of households slipping into and coming out of FI in response to evolving situations, supporting the idea that FI is best conceptualized as a dynamic phenomenon rather than a fixed construct [15,26,27,28,29]. In consideration of the weighty possible implications of FI, comprehending the methods employed by researchers to study FI, and the results obtained, are instrumental in designing food- and nutrition-sensitive policies and their implementation. About two and a half decades ago, many researchers carried out FI research in Nigeria, utilizing various measuring tools like their counterparts in other parts of the world. Several approaches have been established to study FI across global, national, and household/individual domains [11]. About three decades ago, FI measurement tools were used to assess economic access to food, using, for instance, household income or the Household Consumption and Expenditure Survey (HCES) as proxies for food security, although the measures did not capture the experiences of households accessing food or the strategies employed in coping with insufficient food access. To overcome this limitation, the Radimer/Cornell scale (experience-based) was created [30]. In most cases, other experience-based approaches that were developed from [30] hinged on three central themes: “anxiety/uncertainty over running out of food, concerns over and adjustments to the quality, and quantity of food in the diet” [8,30]. The tools used different recall periods (30-day, 12 months) where the gravity of FI is in relation to the quantity of agreeable answers, with a higher number revealing extreme conditions [8,30]. The United States Department of Agriculture (USDA) Household Food Security Survey Module (HFSSM) is another approach commonly used in US-based studies for measuring FI, and it has been extensively adopted in many other countries. The module contains a lineup of questions (18 items) developed from the collective insights of FI at the household level, and it is executed through a survey-based measurement, usually within the timeframe of the prior 12 months. The findings may be presented as an unbroken continuum of severity, or by applying cutoff levels to assign households to four specific categories. In the absence of children, the module utilizes 10-item questions. It is crucial to highlight that HFFSSM adopts a flexible scoring system instead of a strict numerical threshold for classifying households [8,15,31,32].

2. Common Features of Studies

3. Quantifying Food Insecurity

4. Exploring Food Insecurity in Different Settings