Undernutrition is a significant public health issue in Colombia and globally, influenced by multiple factors. The relationship between food insecurity and acute undernutrition in children has been insufficiently explored. To address this, a descriptive, observational, cross-sectional study was conducted involving 70 children under the age of 5, who presented with moderate to severe acute malnutrition. The study assessed family and child food security using the Latin American and Caribbean Food Security Scale (ELCSA). Analysis of the data revealed that when households face challenges in meeting their basic needs, children are generally the least affected. Caregivers tend to prioritize children's diets, opting to reduce food intake among adults over 18 years of age instead. The causes of malnutrition were explored through the perceptions of guardians, who reported that in 30.2% of cases, malnutrition is linked to inadequate feeding and parenting practices. Specific issues noted by parents included children being too lazy to chew, preferring ultra-processed foods, or refusing to eat altogether. The study found that not all children with acute malnutrition experience food insecurity; in fact, the proportion of children suffering from hunger was very low. The findings suggest that malnutrition in children under 5 years of age is not solely determined by food insecurity but also by other factors such as parenting practices and poor feeding habits. Further research is needed to evaluate food access and quality, particularly in terms of dietary diversity, to better understand the needs of each population. Such studies will be essential in guiding public health interventions aimed at preventing, managing, and addressing malnutrition in children.