Malnutrition significantly increases susceptibility to infections, including HIV/AIDS, tuberculosis, and malaria. Protein-energy malnutrition (PEM) impairs immune function by reducing energy availability for immune responses, leading to increased infection risk and poor outcomes. Malnutrition is a major contributor to child mortality, accounting for 54% of deaths under five, and is linked to chronic and acute infections. Severe PEM in children leads to conditions like marasmus and kwashiorkor, which compromise immune function and increase vulnerability to opportunistic infections. Malnutrition also affects growth, nutrient absorption, and metabolic demands, exacerbating the cycle of malnutrition and infection. Infections further worsen malnutrition by causing inflammation, diarrhea, and other complications that reduce nutrient intake and absorption. The immune system requires significant energy for activation and function, which is compromised in malnourished individuals. This creates a vicious cycle where malnutrition weakens immunity, increasing infection risk, which in turn worsens malnutrition. Malnutrition also affects immune cell function, including T cells and macrophages, and impairs the production of protective immune responses. Leptin, a hormone involved in energy balance, plays a key role in immune function, and its levels are reduced in malnourished individuals. Leptin deficiency is associated with increased susceptibility to infections like tuberculosis. Conversely, overnutrition, such as obesity, is also linked to immune dysfunction, with increased inflammation and reduced immune responses. Research highlights the need for improved nutritional strategies to combat both undernutrition and overnutrition. Effective interventions, such as ready-to-use therapeutic food, have been successfully used in emergency situations to treat acute malnutrition. However, chronic malnutrition remains a major global health challenge, requiring long-term solutions to improve food security, nutrition, and public health. The interplay between nutrition, immunity, and infection is complex, and addressing these issues requires integrated approaches to improve health outcomes globally.Malnutrition significantly increases susceptibility to infections, including HIV/AIDS, tuberculosis, and malaria. Protein-energy malnutrition (PEM) impairs immune function by reducing energy availability for immune responses, leading to increased infection risk and poor outcomes. Malnutrition is a major contributor to child mortality, accounting for 54% of deaths under five, and is linked to chronic and acute infections. Severe PEM in children leads to conditions like marasmus and kwashiorkor, which compromise immune function and increase vulnerability to opportunistic infections. Malnutrition also affects growth, nutrient absorption, and metabolic demands, exacerbating the cycle of malnutrition and infection. Infections further worsen malnutrition by causing inflammation, diarrhea, and other complications that reduce nutrient intake and absorption. The immune system requires significant energy for activation and function, which is compromised in malnourished individuals. This creates a vicious cycle where malnutrition weakens immunity, increasing infection risk, which in turn worsens malnutrition. Malnutrition also affects immune cell function, including T cells and macrophages, and impairs the production of protective immune responses. Leptin, a hormone involved in energy balance, plays a key role in immune function, and its levels are reduced in malnourished individuals. Leptin deficiency is associated with increased susceptibility to infections like tuberculosis. Conversely, overnutrition, such as obesity, is also linked to immune dysfunction, with increased inflammation and reduced immune responses. Research highlights the need for improved nutritional strategies to combat both undernutrition and overnutrition. Effective interventions, such as ready-to-use therapeutic food, have been successfully used in emergency situations to treat acute malnutrition. However, chronic malnutrition remains a major global health challenge, requiring long-term solutions to improve food security, nutrition, and public health. The interplay between nutrition, immunity, and infection is complex, and addressing these issues requires integrated approaches to improve health outcomes globally.