disorders of nutrition
Undernutrition
Introduction
Undernutrition is a deficiency of calories or of one or more essential nutrients. Undernutrition may develop because people cannot obtain or prepare food, have a disorder that makes eating or absorbing food difficult, or have a greatly increased need for calories, as occurs during periods of rapid growth. Undernutrition is often obvious: People are underweight, bones often protrude, their skin is dry and inelastic, and their hair is dry and falls out easily. Doctors can usually diagnose undernutrition based on the person's appearance, height and weight, and situation (including information about diet and weight loss). People are given food in gradually increasing amounts, by mouth if possible but sometimes through a tube passed down the throat to the stomach or inserted into a vein (intravenously). is usually thought of as a deficiency primarily of calories (that is, overall food consumption) or of protein. Overview of Vitamins and Malnutritionis an imbalance between the nutrients the body needs and the nutrients it gets. Thus, malnutrition also includes overnutrition (consumption of too many calories or too much of any specific nutrient—protein, fat, vitamin, mineral, or other dietary supplement), as well as undernutrition. The number of undernourished people in the world has been increasing since 2014. InThe State of Food Security and Nutrition in the World 2023, the United Nations Food and Agriculture Organization (FAO) reported that almost 735 million people, or 9.2% of the global population, were undernourished in 2023, which is 122 million more people than in 2019. Most live in countries with high rates of food insecurity. The prevalence of undernutrition in Africa increased from 19.4% in 2021 to 19.7% in 2022. But in Asia, the prevalence of undernutrition decreased from 8.8% in 2021 to 8.5% in 2022, a decrease of more than 12 million people. However, these numbers are 58 million above prepandemic levels. Almost 600 million people are estimated to be chronically undernourished in 2030. This estimate is 23 million more than it would have been if the war in Ukraine had not occurred and 119 million more than it would be if neither the pandemic nor the war in Ukraine had occurred. Undernutrition progresses in stages. It may develop slowly or very rapidly, as may occur when cancer is rapidly advancing. When not enough calories are consumed, the body first breaks down its own fat and uses it for calories—much like burning the furniture to keep a house warm. After fat stores are used up, the body may break down its other tissues, such as muscle and tissues in internal organs, leading to serious problems, including death. 