Measurements of a child’s growth provide the key information for the presence of malnutrition, but weight and height measurements alone can lead to failure to recognize kwashiorkor and an underestimation of the severity of malnutrition in children.

Measures have been taken to reduce child malnutrition. Studies for the World Bank found that, from 1970 to 2000, the number of malnourished children decreased by 20 percent in developing countries. Iodine supplement trials in pregnant women have been shown to reduce offspring deaths during infancy and early childhood by 29 percent. However, universal salt iodization has largely replaced this intervention.

The Progresa program in Mexico combined conditional cash transfers with nutritional education and micronutrient-fortified food supplements; this resulted in a 10 percent reduction the prevalence of stunting in children 12–36 months old. Milk fortified with zinc and iron reduced the incidence of diarrhea by 18 percent in a study in India.

Physical examination to examine muscle wasting, laboratory investigations.

Hypothermia can occur. To prevent or treat this, the child can be kept warm with covering including of the head or by direct skin-to-skin contact with the mother or father and then covering both parent and child. Prolonged bathing or prolonged medical exams should be avoided. Warming methods are usually most important at night.

In response to child malnutrition, the Bangladeshi government recommends ten steps for treating severe malnutrition. They are to prevent or treat dehydration, low blood sugar, low body temperature, infection, correct electrolyte imbalances and micronutrient deficiencies, start feeding cautiously, achieve catch-up growth, provide psychological support, and prepare for discharge and follow-up after recovery.

Among those patients who are hospitalized, nutritional support improves protein, colorie intake and weight.

Growth stunting is identified by comparing measurements of children's heights to the World Health Organization 2006 growth reference population: children who fall below the fifth percentile of the reference population in height for age are defined as stunted, regardless of the reason. The lower than fifth percentile corresponds to less than two standard deviations of the WHO Child Growth Standards median.

As an indicator of nutritional status, comparisons of children's measurements with growth reference curves may be used differently for populations of children than for individual children. The fact that an individual child falls below the fifth percentile for height for age on a growth reference curve may reflect normal variation in growth within a population: the individual child may be short simply because both parents carried genes for shortness and not because of inadequate nutrition. However, if substantially more than 5% of an identified child population have height for age that is less than the fifth percentile on the reference curve, then the population is said to have a higher-than-expected prevalence of stunting, and malnutrition is generally the first cause considered.

Although protein energy malnutrition is more common in low-income countries, children from higher-income countries are also affected, including children from large urban areas in low socioeconomic neighborhoods. This may also occur in children with chronic diseases, and children who are institutionalized or hospitalized for a different diagnosis. Risk factors include a primary diagnosis of intellectual disability, cystic fibrosis, malignancy, cardiovascular disease, end stage renal disease, oncologic disease, genetic disease, neurological disease, multiple diagnoses, or prolonged hospitalization. In these conditions, the challenging nutritional management may get overlooked and underestimated, resulting in an impairment of the chances for recovery and the worsening of the situation.

PEM is fairly common worldwide in both children and adults and accounts for 6 million deaths annually. In the industrialized world, PEM is predominantly seen in hospitals, is associated with disease, or is often found in the elderly.

A large percentage of children that suffer from PEM also have other co-morbid conditions. The most common co-morbidities are diarrhea (72.2% of a sample of 66 subjects) and malaria (43.3%). However, a variety of other conditions have been observed with PEM, including sepsis, severe anaemia, bronchopneumonia, HIV, tuberculosis, scabies, chronic suppurative otitis media, rickets, and keratomalacia. These co-morbidities tax already malnourished children and may prolong hospital stays initially for PEM and may increase the likelihood of death.

Three main things are needed to reduce stunting:

- a kind of environment where political commitment can thrive (also called an "enabling environment")

- applying several nutritional modifications or changes in a population on a large scale which have a high benefit and a low cost

- a strong foundation that can drive change (food security, empowerment of women and a supportive health environment through increasing access to safe water and sanitation).

To prevent stunting, it is not just a matter of providing better nutrition but also access to clean water, improved sanitation (hygienic toilets) and hand washing at critical times (summarised as "WASH"). Without provision of toilets, prevention of tropical intestinal diseases, which may affect almost all children in the developing world and lead to stunting will not be possible.

Studies have looked at ranking the underlying determinants in terms of their potency in reducing child stunting and found in the order of potency:

- percent of dietary energy from non-staples (greatest impact)

- access to sanitation and women's education

- access to safe water

- women's empowerment as measured by the female-to-male life expectancy ratio

- per capita dietary energy supply

Three of these determinants should receive attention in particular: access to sanitation, diversity of calorie sources from food supplies, and women's empowerment. A study by the Institute of Development Studies has stressed that: "The first two should be prioritized because they have strong impacts yet are farthest below their desired levels".

The goal of UN agencies, governments and NGO is now to optimise nutrition during the first 1000 days of a child's life, from pregnancy to the child's second birthday, in order to reduce the prevalence of stunting. The first 1000 days in a child's life are a crucial "window of opportunity" because the brain develops rapidly, laying the foundation for future cognitive and social ability. Furthermore, it is also the time when young children are the most at risk of infections that lead to diarrhoea. It is the time when they stop breast feeding (weaning process), begin to crawl, put things in their mouths and become exposed to faecal matter from open defecation and environmental enteropathies.

In order to avoid problems, the person must be rehabilitated with small but frequent rations, given every two to four hours. During one week, the diet, hyperglucidic, is gradually enriched in protein as well as essential elements: sweet milk with mineral salts and vitamins. The diet may include lactases - so that children who have developed lactose intolerance can ingest dairy products - and antibiotics - to compensate for immunodeficiency. After two to three weeks, the milk is replaced by boiled cereals fortified with minerals and vitamins until its mass is at least 80% of normal weight. Traditional food can then be reintroduced. The child is considered healed when his mass reaches 85% of normal.

For the individual, prevention consists of ensuring they eat plenty of food, varied enough to provide a nutritionally complete diet.

Starvation can be caused by factors, other than illness, outside of the control of the individual. The Rome Declaration on World Food Security outlines several policies aimed at increasing food security and, consequently, preventing starvation. These include:

- Poverty reduction

- Prevention of wars and political instability

- Food aid

- Agricultural sustainability

- Reduction of economic inequality

Supporting farmers in areas of food insecurity through such measures as free or subsidized fertilizers and seeds increases food harvest and reduces food prices.

Persons in prisons, concentration camps, and refugee camps tend to suffer from marasmus, due to poor nutrition.

Starving patients can be treated, but this must be done cautiously to avoid refeeding syndrome. Rest and warmth must be provided and maintained. Small sips of water mixed with glucose should be given in regular intervals. Fruit juices can also be given. Later, food can be given gradually in small quantities. The quantity of food can be increased over time. Proteins may be administered intravenously to raise the level of serum proteins.

Vitamin poisoning is the condition of overly high storage levels of vitamins, which can lead to toxic symptoms. The medical names of the different conditions are derived from the vitamin involved: an excess of vitamin A, for example, is called "hypervitaminosis A".

Iron overload disorders are diseases caused by the overaccumulation of iron in the body. Organs commonly affected are the liver, heart and endocrine glands in the mouth.

Not only the causes, but also the complications of the disorder must be treated, including infections, dehydration, and circulation disorders, which are frequently lethal and lead to high mortality if ignored. Initially, the child is given dried skim milk powder mixed with boiled water which is then followed by mixing it with vegetable oils and finally sugar. Once children start to recover, they should have more balanced diets which meet their nutritional needs. Infections are also common in children with marasmus. So, they are also treated with antibiotics. Ultimately, marasmus can progress to the point of no return when the body's ability for protein synthesis is lost. At this point, attempts to correct the disorder by giving food or protein are futile.

Obesity is caused by eating too many calories compared to the amount of exercise the individual is performing, causing a distorted energy balance. It can lead to diseases such as cardiovascular disease and diabetes. Obesity is a condition in which the natural energy reserve, stored in the fatty tissue of humans and other mammals, is increased to a point where it is associated with certain health conditions or increased mortality.

The low-cost food that is generally affordable to the poor in affluent nations is low in nutritional value and high in fats, sugars and additives. In rich countries, therefore, obesity is often a sign of poverty and malnutrition while in poorer countries obesity is more associated with wealth and good nutrition. Other non-nutritional causes for obesity included: sleep deprivation, stress, lack of exercise, and heredity.

Acute overeating can also be a symptom of an eating disorder.

Goitrogenic foods can cause goitres by interfering with iodine uptake.

Obesity increases health risks, including diabetes, cancer, cardiovascular disease, high blood pressure, and non-alcoholic fatty liver disease, to name a few. Reduction of obesity lowers those risks.

A 1-kg loss of body weight has been associated with an approximate 1-mm Hg drop in blood pressure.

Social conditions such as poverty, social isolation and inability to get or prepare preferred foods can cause unintentional weight loss, and this may be particularly common in older people. Nutrient intake can also be affected by culture, family and belief systems. Ill-fitting dentures and other dental or oral health problems can also affect adequacy of nutrition.

Loss of hope, status or social contact and spiritual distress can cause depression, which may be associated with reduced nutrition, as can fatigue.

There is no single, specific test for malabsorption. As for most medical conditions, investigation is guided by symptoms and signs. A range of different conditions can produce malabsorption and it is necessary to look for each of these specifically. Many tests have been advocated, and some, such as tests for pancreatic function are complex, vary between centers and have not been widely adopted. However, better tests have become available with greater ease of use, better sensitivity and specificity for the causative conditions. Tests are also needed to detect the systemic effects of deficiency of the malabsorbed nutrients (such as anaemia with vitamin B12 malabsorption).

According to the 2007 AHRQ National Inpatient Sample, in a projected 129,164 hospital encounters in the United States, cachexia was listed as at least one of up to 14 recorded diagnosis codes based on a sample of 26,325 unweighted encounters. A sample of 32,778 unweighted US outpatient visits collected by the CDC's National Ambulatory Medical Care Survey did not list any visits where cachexia was one of up to three recorded diagnoses treated during the visit.

Antiretrovirals and anabolic steroids have been used to treat HIV wasting syndrome. Additionally, an increase in protein-rich foods such as peanut butter, eggs, and cheese can assist in controlling the loss of muscle mass.

Only limited treatment options exist for patients with clinical cancer cachexia. Current strategy is to improve appetite by using appetite stimulants to ensure adequate intake of nutrients. Pharmacological interventions with appetite stimulants, nutrient supplementation, 5-HT antagonists and Cox-2 inhibitor have been used to treat cancer cachexia, but with limited effect.

Studies using a more calorie-dense (1.5 kcals/ml) and higher protein supplementation have suggested at least weight stabilization can be achieved, although improvements in lean body mass have not been observed in these studies.

Therapeutic strategies have been based on either blocking cytokines synthesis or their action. Thalidomide has been demonstrated to suppress TNF-alpha production in monocytes "in vitro" and to normalize elevated TNF-alpha levels "in vivo". A randomized, placebo-controlled trial in patients with cancer cachexia showed the drug was well tolerated and effective at attenuating loss of weight and lean body mass (LBM) in patients with advanced pancreatic cancer. An improvement in the LBM and improved quality of life were also observed in a randomized, double-blind trial using a protein and energy-dense, omega-3 fatty acids-enriched oral supplement, provided its consumption was equal or superior to 2.2 g of eicosapentaenoic acid per day. It is also through decreasing TNF-alpha production. However, data arising from a large, multicenter, double-blind, placebo-controlled trial indicate EPA administration alone is not successful in the treatment of weight loss in patients with advanced gastrointestinal or lung cancer.

Peripheral muscle proteolysis, as it occurs in cancer cachexia, serves to mobilize amino acids required for the synthesis of liver and tumor protein. Therefore, the administration of exogenous amino acids may theoretically serve as a protein-sparing metabolic fuel by providing substrates for both muscle metabolism and gluconeogenesis. Studies have demonstrated dietary supplementation with a specific combination of high protein, leucine and fish oil improves muscle function and daily activity and the immune response in cachectic tumor-bearing mice. In addition, β-hydroxy-β-methyl butirate derived from leucine catabolism used as a supplement in tumor-bearing rats prevents cachexia by modifying NF-κB expression.

A phase-2 study involving the administration of antioxidants, pharmaconutritional support, progestin (megestrol acetate and medroxyprogesterone acetate), and anticyclooxygenase-2 drugs, showed efficacy and safety in the treatment of patients with advanced cancer of different sites suffering cachexia. These data reinforce the use of the multitargeted therapies (nutritional supplementation, appetite stimulants, and physical activity regimen) in the treatment of cancer cachexia.

New studies indicate NSAIDS, like Sulindac, were found to significantly decrease cachexia.

Also studies have shown branched-chain amino acids can return the metabolism of a cachectic patient from catabolic-losing weight- to anabolic- increasing muscle, in over 55% of patients. Branched-chain amino acids consist primarily of leucine and valine. In a research paper published by the Indian J of Palliat Care, the effects the findings concluded that bcaa's interfere with brain serotonergic activity and inhibit the overexpression of critical muscular proteolytic pathways. The potential role of branched-chain amino acids as antianorexia and anticachexia agents was proposed many years ago, but experimental studies and clinical trials have since tested their ability to stimulate food intake and counteract muscle wasting in anorectic, weight-losing patients. In experimental models of cancer cachexia, BCAAs were able to induce a significant suppression in the loss of body weight, producing a significant increase in skeletal muscle wet weight[30] as well as in muscle performance and total daily activity.

The conditionally essential amino acid glutamine has been used as a component of oral supplementation to reverse cachexia in patients with advanced cancer or HIV/AIDS.

Refeeding syndrome can be fatal if not recognized and treated properly. An awareness of the condition and a high index of suspicion are required in order to make the diagnosis. The electrolyte disturbances of the refeeding syndrome can occur within the first few days of refeeding. Close monitoring of blood biochemistry is therefore necessary in the early refeeding period. In critically ill patients admitted to an intensive care unit, if phosphate drops to below 0.65 mmol from a previously normal level within three days of starting enteral or parenteral nutrition, caloric intake should be reduced to 480 kcals per day for at least two days whilst electrolytes are replaced. Prescribing thiamine, vitamin B complex (strong) and a multivitamin and mineral preparation is recommended. Biochemistry should be monitored regularly until it is stable. Although clinical trials are lacking in patients other than those admitted to an intensive care, it is commonly recommended that energy intake should remain lower than that normally required for the first 3–5 days of treatment of refeeding syndrome.

See NICE Clinical guideline CG32, section 6.6. On first aid and preliminary medical management, see for example the guidance by HMS Monmouth medical officer.

Treatment is directed largely towards management of underlying cause:

- Replacement of nutrients, electrolytes and fluid may be necessary. In severe deficiency, hospital admission may be required for nutritional support and detailed advice from dietitians. Use of enteral nutrition by naso-gastric or other feeding tubes may be able to provide sufficient nutritional supplementation. Tube placement may also be done by percutaneous endoscopic gastrostomy, or surgical jejunostomy. In patients whose intestinal absorptive surface is severely limited from disease or surgery, long term total parenteral nutrition may be needed.

- Pancreatic enzymes are supplemented orally in pancreatic insufficiency.

- Dietary modification is important in some conditions:

- Gluten-free diet in coeliac disease.

- Lactose avoidance in lactose intolerance.

- Antibiotic therapy to treat Small Bowel Bacterial overgrowth.

- Cholestyramine or other bile acid sequestrants will help reducing diarrhoea in bile acid malabsorption.

Malnutrition is an important health concern in Tibet. According to a study conducted in 1994/1995 in eleven districts of Tibet, malnutrition affected more than half of the children from 1–7 years old. The major cause was poverty.