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Malnutrition

Malnutrition is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Malnutrition rather than just read about it. In short: Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues and form.

Malnutrition — main illustration
Malnutrition — illustration

Key takeaways

  • Malnutrition belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Malnutrition to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Malnutrition from memory before moving on to harder problems.

Reference excerpt

Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues and form. Malnutrition is a category of diseases that includes Undernutrition and overnutrition. Undernutrition is a lack of nutrients, which can result in stunted growth, wasting, and being underweight. A surplus of nutrients causes overnutrition, which can result in obesity or toxic levels of micronutrients. In some developing countries, overnutrition in the form of obesity is beginning to appear within the same communities as undernutrition. Malnutrition is reported to occur in US healthcare and worldwide up to 40% of hospitalized patients are estimated to be affected by disease-related malnutrition. Most clinical studies use the term 'malnutrition' to refer to undernutrition. However, the use of 'malnutrition' instead of 'undernutrition' makes it impossible to distinguish between undernutrition and overnutrition, a less acknowledged form of malnutrition. Accordingly, a 2019 report by The Lancet Commission suggested expanding the definition of malnutrition to include "all its forms, including obesity, undernutrition, and other dietary risks." The World Health Organization and The Lancet Commission have also identified "[t]he double burden of malnutrition", which occurs from "the coexistence of overnutrition (overweight and obesity) alongside undernutrition (stunted growth and wasting)."

Type

Undernutrition

Undernutrition can occur either due to protein-energy wasting or as a result of micronutrient deficiencies. It adversely affects physical and mental functioning, and causes changes in body composition and body cell mass. Undernutrition is a major health problem, causing the highest mortality rate in children, particularly in those under 5 years, and is responsible for long-lasting physiologic effects. It is a barrier to the complete physical and mental development of children. Undernutrition can manifest as stunting, wasting, and being underweight. If undernutrition occurs during pregnancy, or before two years of age, it may result in permanent problems with physical and mental development. Extreme undernutrition can cause starvation, chronic hunger, Severe Acute Malnutrition (SAM), or Moderate Acute Malnutrition (MAM). The signs and symptoms of micronutrient deficiencies depend on which micronutrient is lacking. However, undernourished people are often thin and short, with very poor energy levels; and swelling in the legs and abdomen is also common. People who are undernourished often get infections and frequently feel cold.

Micronutrient undernutrition Micronutrient undernutrition results from insufficient intake of vitamins and minerals. Worldwide, deficiencies in iodine, Vitamin A, and iron are the most common. Children and pregnant women in low-income countries are at especially high risk for micronutrient deficiencies. Anemia is most commonly caused by iron deficiency, but can also result from other micronutrient deficiencies and diseases. Vitamin B12 deficiency may cause anemia, but not in all cases, in which may result in changes in consciousness or thinking, or even irreversible neurological damage. This condition can have major health consequences. It is possible to have overnutrition simultaneously with micronutrient deficiencies; this condition is termed the double burden of malnutrition.

Protein-energy malnutrition 'Undernutrition' sometimes refers specifically to protein–energy malnutrition (PEM). This condition involves both micronutrient deficiencies and an imbalance of protein intake and energy expenditure. It differs from calorie restriction in that calorie restriction may not result in negative health effects. Hypoalimentation (underfeeding) is one cause of undernutrition. Two forms of PEM are kwashiorkor and marasmus; both commonly coexist.

Kwashiorkor is primarily caused by inadequate protein intake. Its symptoms include edema, wasting, liver enlargement, hypoalbuminaemia, and steatosis; the condition may also cause depigmentation of skin and hair. The disorder is further identified by a characteristic swelling of the belly, and extremities which disguises the patient's undernourished condition. 'Kwashiorkor' means 'displaced child' and is derived from the Ga language of coastal Ghana in West Africa. It means "the sickness the baby gets when the next baby is born," as it often occurs when the older child is deprived of breastfeeding and weaned to a diet composed largely of carbohydrates. Marasmus (meaning 'to waste away') can result from a sustained diet that is deficient in both protein and energy. This causes their metabolism to adapt to prolong survival. The primary symptoms are severe wasting, leaving little or no edema; minimal subcutaneous fat; and abnormal serum albumin levels. It is traditionally seen in cases of famine, significant food restriction, or severe anorexia. Conditions are characterized by extreme wasting of the muscles and a gaunt expression.

Overnutrition Excessive consumption of energy-dense foods and drinks and limited physical activity causes overnutrition. It causes overweight, defined as a body mass index (BMI) of 25 or more, and can lead to obesity (a BMI of 30 or more). Obesity has become a major health issue worldwide. Overnutrition is linked to chronic non-communicable diseases like diabetes, certain cancers, and cardiovascular diseases. Hence identifying and addressing the immediate risk factors has become a major health priority. The recent evidence on the impact of diet-induced obesity in fathers and mothers around the time of conception is identified to negatively program the health outcomes of multiple generations. According to UNICEF, at least 1 in every 10 children under five is overweight in 33 countries.

Effects

… excerpt ends here. Continue reading the full article.

Illustrations

Malnutrition illustration
Malnutrition: Prevalence of undernourishment (2022–2024 average)[23]
Prevalence of undernourishment (2022–2024 average)[23]
Malnutrition: Number of undernourished people (2022–2024 average)[24]
Number of undernourished people (2022–2024 average)[24]
Malnutrition: The prevalence of undernourishment (PoU) was still higher in 2022 than before the pandemic in 58% of countries, and the situation is worse in low-income countries (77%).
The prevalence of undernourishment (PoU) was still higher in 2022 than before the pandemic in 58% of countries, and the situation is worse in low-income countries (77%).
Malnutrition: Child in the United States with signs of kwashiorkor, a dietary protein deficiency
Child in the United States with signs of kwashiorkor, a dietary protein deficiency

Worked examples

Example 1 — a first encounter with Malnutrition

Start with the simplest possible case. Write down what Malnutrition claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Malnutrition before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Malnutrition ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Malnutrition

In research
Malnutrition appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Malnutrition in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Malnutrition is common in secondary-school and first-year university syllabi. It links to neighbouring topics Eating behaviors, Global issues, Hazards of outdoor recreation, so understanding it makes those chapters shorter.
In everyday life
Look for Malnutrition outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Malnutrition in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Malnutrition means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Malnutrition out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Malnutrition in simple terms?

Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues and form.

Why does Malnutrition matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Malnutrition?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Malnutrition.

Tags

  • Eating behaviors
  • Global issues
  • Hazards of outdoor recreation
  • Health effects of food and nutrition
  • Limbic system
  • Malnutrition
  • Motivation
  • Neuropsychology

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