---
title: "Human nutrition"
chunk: 7/20
source: "https://en.wikipedia.org/wiki/Human_nutrition"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:55:25.210940+00:00"
instance: "kb-cron"
---

UNICEF defines undernutrition "as the outcome of insufficient food intake (hunger) and repeated infectious diseases. Undernutrition includes being underweight for one's age, too short for one's age (stunted growth), dangerously thin (muscle wasting), and deficient in vitamins and minerals (micronutrient malnutrition). Under nutrition causes 53% of deaths of children under five across the world. It has been estimated that undernutrition is the underlying cause for 35% of child deaths. The Maternal and Child Nutrition Study Group estimate that under nutrition, "including fetal growth restriction, stunting, wasting, deficiencies of vitamin A and zinc along with suboptimum breastfeeding—is a cause of 3.1 million child deaths and infant mortality, or 45% of all child deaths in 2011".
When humans are undernourished, they no longer maintain normal bodily functions, such as growth, resistance to infection, or have insufficient drive for every everyday tasks and unsatisfactory performance in school or work. Major causes of under nutrition in young children include lack of proper breast feeding for infants and illnesses such as diarrhea, pneumonia, malaria, and HIV/AIDS. According to UNICEF 146 million children across the globe, that one out of four under the age of five, are underweight. The number of underweight children has decreased since 1990, from 33 percent to 28 percent between 1990 and 2004. Underweight and stunted children are more susceptible to infection, more likely to fall behind in academics and develop non-infectious diseases, ultimately affecting their livelihood. Therefore, undernutrition can result in an accumulation of afflictions and health deficiencies which results in less productivity individually and as a community.
Many children are born with the inherent disadvantage of low birth weight, often caused by intrauterine growth restriction and poor maternal nutrition, which results in affected growth, development and health throughout the course of their lifetime. Children born at low birth weight (less than 5.5 pounds or 2.5 kg), are less likely to be healthy and are more susceptible to disease and early death. Those born at low birth weight also are likely to have a depressed immune system, which can increase their chances of heart disease and diabetes later on in life. Because 96% of low birth weight occurs in the developing world, low birth weight has been associated with childbirth in impoverished areas where the birth mother typically exhibits poor nutritional status under harsh and demanding living conditions.
Stunting and other forms of undernutrition reduces a child's chance of survival and hinders their optimal growth and health. Stunting has demonstrated association with poor brain development, which reduces cognitive ability, academic performance and future earning potential. Important determinants of stunting include the quality and frequency of infant and child feeding, infectious disease susceptibility, and the mother's nutrition and health status. Undernourished mothers are more likely to birth stunted children, perpetuating a cycle of undernutrition and poverty. Stunted children are more likely to develop obesity and chronic diseases upon reaching adulthood. Therefore, malnutrition resulting in stunting can further worsen the obesity epidemic, especially in low and middle income countries. This creates even new economic and social challenges for vulnerable impoverished groups.
Data on global and regional food supply shows that consumption rose from 2011 to 2012 in all regions. Diets became more diverse, with a decrease in consumption of cereals and roots and an increase in fruits, vegetables, and meat products. However, this increase masks the discrepancies between nations, where Africa, in particular, saw a decrease in food consumption over the same years. This information is derived from food balance sheets that reflect national food supplies, however, this does not necessarily reflect the distribution of micronutrients and macronutrients. Often inequality in food access leaves distribution which uneven, resulting in undernourishment for some and obesity for others.
Undernourishment, or hunger, according to the Food and Agriculture Organization (FAO), is dietary intake below the minimum daily energy requirement. The amount of undernourishment is calculated utilizing the average amount of food available for consumption, the size of the population, the relative disparities in access to the food, and the minimum calories required for each individual. According to FAO, 868 million people (12% of the global population) were undernourished in 2012. This has decreased across the world since 1990, in all regions except for Africa, where undernourishment has steadily increased. However, the rates of decrease are not sufficient to meet the first Millennium Development Goal of halving hunger between 1990 and 2015. The global financial, economic, and food price crisis in 2008 drove many people to hunger, especially women and children. The spike in food prices prevented many people from escaping poverty, because the poor spend a larger proportion of their income on food and farmers are net consumers of food. High food prices cause consumers to have less purchasing power and to substitute more-nutritious foods with low-cost alternatives.

=== Adult overweight and obesity ===

Malnutrition in Industrialized nations is primarily due to non-nutritious carbohydrates sources resulting in excess caloric intake, which has contributed to the obesity epidemic affecting both developed and certain developing nations. In 2008, 35% of adults above the age of 20 years were overweight (BMI ≥ 25 kg/m2), a prevalence that has doubled worldwide between 1980 and 2008. Also 10% of men and 14% of women were obese, with a body mass index (BMI) greater than 30. Rates of overweight and obesity vary across the globe, with the highest prevalence in the Americas, followed by European nations, where over 50% of the population is overweight or obese.
Obesity is more prevalent among upper-middle to high income groups compared to lower income divisions. Women are more likely than men to be obese, where the rate of obesity in women doubled from 8% to 14% between 1980 and 2008. Being overweight as a child has become an increasingly important statistic as an indicator for later development of obesity and non-infectious diseases such as cardiovascular disease. In several western European nations, the prevalence of overweight and obese children rose by 10% from 1980 to 1990, a rate that has begun to accelerate recently.