A diet with carefully controlled levels of the amino acids leucine, isoleucine, and valine must be maintained at all times in order to prevent neurological damage. Since these three amino acids occur in all natural protein, and most natural foods contain some protein, any food intake must be closely monitored, and day-to-day protein intake calculated on a cumulative basis, to ensure individual tolerance levels are not exceeded at any time. As the MSUD diet is so protein-restricted, and adequate protein is a requirement for all humans, tailored metabolic formula containing all the other essential amino acids, as well as any vitamins, minerals, omega-3 fatty acids and trace elements (which may be lacking due to the limited range of permissible foods), are an essential aspect of MSUD management. These complement the MSUD patient's natural food intake to meet normal nutritional requirements without causing harm. If adequate calories cannot be obtained from natural food without exceeding protein tolerance, specialised low protein products such as starch-based baking mixtures, imitation rice and pasta may be prescribed, often alongside a protein-free carbohydrate powder added to food and/or drink, and increased at times of metabolic stress. Some patients with MSUD may also improve with administration of high doses of thiamine, a cofactor of the enzyme that causes the condition.

Keeping MSUD under control requires careful monitoring of blood chemistry, both at home and in a hospital setting. DNPH or specialised dipsticks may be used to test the patient's urine for ketones (a sign of metabolic decompensation), when metabolic stress is likely or suspected. Fingerstick tests are performed regularly and sent to a laboratory to determine blood levels of leucine, isoleucine, and valine. Regular metabolic consultations, including blood-draws for full nutritional analysis, are recommended; especially during puberty and periods of rapid growth. MSUD management also involves a specially tailored metabolic formula, a modified diet, and lifestyle precautions such as avoiding fatigue and infections, as well as consuming regular, sufficient calories in proportion to physical stress and exertion. Without sufficient calories, catabolism of muscle protein will result in metabolic crisis. Those with MSUD must be hospitalised for intravenous infusion of sugars and nasogastric drip-feeding of formula, in the event of metabolic decompensation, or anorexia, diarrhea or vomiting. Food avoidance, rejection of formula and picky eating are all common problems with MSUD. Some patients may need to receive all or part of their daily nutrition through a feeding tube.

Ketosis is deliberately induced by use of a ketogenic diet as a medical intervention in cases of intractable epilepsy. Other uses of low-carbohydrate diets remain controversial. Carbohydrate deprivation to the point of ketosis has been argued to have both negative and positive effects on health.

Treatment for glycogen storage disease type III may involve a high-protein diet, in order to facilitate gluconeogenesis. Additionally the individual may need:

- IV glucose (if oral route is inadvisable)

- Nutritional specialist

- Vitamin D (for osteoporosis/secondary complication)

- Hepatic transplant (if complication occurs)

In the middle of the 20th century the principal treatment for some of the amino acid disorders was restriction of dietary protein and all other care was simply management of complications. In the past twenty years, enzyme replacement, gene therapy, and organ transplantation have become available and beneficial for many previously untreatable disorders. Some of the more common or promising therapies are listed:

Once ketotic hypoglycemia is suspected and other conditions excluded, appropriate treatment reduces the frequency and duration of episodes. Extended fasts should be avoided. The child should be given a bedtime snack of carbohydrates (e.g. spaghetti or pasta or milk) and should be awakened and fed after the usual duration of sleep. If the child is underweight, a daily nutritional supplement may be recommended. Raw cornstarch dissolved in a beverage helps individuals with hypoglycemia, especially that caused by Glycogen Storage Disease, sustain their blood sugars for longer periods of time and may be given at bedtime.

If a spell begins, carbohydrates and fluids should be given promptly. If vomiting prevents this, the child should be taken to the local emergency department for a few hours of intravenous saline and dextrose. This treatment is often expedited by supplying the parents with a letter describing the condition and recommended treatment.

Metabolic disorders can be treatable by nutrition management, especially if detected early. It is important for dieticians to have knowledge of the genotype to therefore create a treatment that will be more effective for the individual.

Five interventional strategies can be used:

- Adding zinc to soil, called agronomic biofortification, which both increases crop yields and provides more dietary zinc.

- Adding zinc to food, called fortification.

- Adding zinc rich foods to diet. The foods with the highest concentration of zinc are proteins, especially animal meats, the highest being oysters. Per ounce, beef, pork, and lamb contain more zinc than fish. The dark meat of a chicken has more zinc than the light meat. Other good sources of zinc are nuts, whole grains, legumes, and yeast. Although whole grains and cereals are high in zinc, they also contain chelating phytates which bind zinc and reduce its bioavailability.

- Oral repletion via tablets (e.g. zinc gluconate) or liquid (e.g. zinc acetate). Oral zinc supplementation in healthy infants more than six months old has been shown to reduce the duration of any subsequent diarrheal episodes by about 11 hours.

- Oral repletion via multivitamin/mineral supplements containing zinc gluconate, sulfate, or acetate. It is not clear whether one form is better than another. Zinc is also found in some cold lozenges, nasal sprays, and nasal gels.

The treatment or management of cachexia depends on the underlying causes, the general prognosis and other person related factors. Reversible causes, underlying diseases and contributing factors are treated if possible and acceptable. A growing body of evidence supports the efficacy of (HMB) as a treatment for reducing, or even reversing, the loss of muscle mass, muscle function, and muscle strength that occurs in hypercatabolic disease states such as cachexia; consequently, it is recommended that both the prevention and treatment of muscle wasting conditions include supplementation with HMB, regular resistance exercise, and consumption of a high-protein diet. Progestins such as megestrol acetate are a treatment option in refractory cachexia with anorexia as a major symptom.

Cachexia occurs less frequently now in HIV/AIDS than in the past due to the advent of highly active antiretroviral therapy (HAART). Treatment involving different combinations for cancer cachexia is recommended in Europe, as a combination of nutrition, medication and non-drug-treatment may be more effective than monotherapy. Non-drug therapies which have been shown to be effective in cancer induced cachexia include nutritional counselling, psychotherapeutic interventions, and physical training. Anabolic-androgenic steroids like oxandrolone may be beneficial in cancer cachexia but their use is recommended for maximal 2 weeks since a longer duration of treatment increases the burden from side effects.

Other drugs that have been used or are being investigated in cachexia therapy, but which lack conclusive evidence of efficacy or safety, and are not generally recommended include:

- Thalidomide and cytokine antagonists

- Cannabinoids

- Omega-3 fatty acids, including eicosapentaenoic acid (EPA)

- Non-steroidal anti-inflammatory drugs

- Prokinetics

- Ghrelin and ghrelin receptor agonist

- Anabolic catabolic transforming agents such as MT-102

- Selective androgen receptor modulators

- Cyproheptadine

- Hydrazine

Medical marijuana has been allowed for the treatment of cachexia in some US states, such as Illinois, Maryland, Delaware, Nevada, Michigan, Washington, Oregon, California, Colorado, New Mexico, Arizona, Vermont, New Jersey, Rhode Island, Maine, and New York Hawaii and Connecticut.

There is insufficient evidence to support the use of oral fish oil for the management of cachexia associated with advanced cancer.

Children "outgrow" ketotic hypoglycemia, presumably because fasting tolerance improves as body mass increases. In most the episodes become milder and more infrequent by 4 to 5 years of age and rarely occur after age 9. Onset of hypoglycemia with ketosis after age 5 or persistence after age 7 should elicit referral and an intensive search for a more specific disease.

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.

Some clinicians regard eliminating carbohydrates as unhealthy and dangerous. However, it is not necessary to eliminate carbohydrates from the diet completely to achieve ketosis. Other clinicians regard ketosis as a safe biochemical process that occurs during the fat-burning state. Ketosis, which is accompanied by gluconeogenesis (the creation of glucose de novo from pyruvate), is the specific state that concerns some clinicians. However, it is unlikely for a normally functioning person to reach life-threatening levels of ketosis, defined as serum beta-hydroxybutyrate (B-OHB) levels above 15 millimolar (mM) compared to ketogenic diets among non diabetics, which "rarely run serum B-OHB levels above 3 mM." This is avoided with proper basal secretion of pancreatic insulin. People who are unable to secrete basal insulin, such as type 1 diabetics and long-term type II diabetics, are liable to enter an unsafe level of ketosis, eventually resulting in a coma that requires emergency medical treatment. The anti-ketosis conclusions have been challenged by a number of doctors and advocates of low-carbohydrate diets, who dispute assertions that the body has a preference for glucose and that there are dangers associated with ketosis.

The first line treatment is change of lifestyle (e.g., Dietary Guidelines for Americans and physical activity). However, if in three to six months of efforts at remedying risk factors prove insufficient, then drug treatment is frequently required. Generally, the individual disorders that compose the metabolic syndrome are treated separately. Diuretics and ACE inhibitors may be used to treat hypertension. Cholesterol drugs may be used to lower LDL cholesterol and triglyceride levels, if they are elevated, and to raise HDL levels if they are low. Use of drugs that decrease insulin resistance, e.g., metformin and thiazolidinediones, is controversial; this treatment is not approved by the U.S. Food and Drug Administration. Weight loss medications may result in weight loss. As obesity is often recognized as the culprit behind many of the additional symptoms, with weight loss and lifestyle changes in diet, physical activity, the need for other medications may diminish.

A 2003 study indicated cardiovascular exercise was therapeutic in approximately 31% of cases. The most probable benefit was to triglyceride levels, with 43% showing improvement; but fasting plasma glucose and insulin resistance of 91% of test subjects did not improve.

Many other studies have supported the value of physical activity and dietary modifications to treat metabolic syndrome. Some natural compounds, like ursolic acid, have been suggested as a treatment for obesity/metabolic syndrome based on the results of extensive research involving animal models; it is argued, however, that there is still a lack of data regarding the use of ursolic acid in humans, as phase-II/III trials of that drug have not been carried so far.

Restricting the overall dietary carbohydrate intake is more effective in reducing the most common symptoms of metabolic syndrome than the more commonly prescribed reduction in dietary fat intake.

The combination preparation simvastatin/sitagliptin (marketed as Juvisync) was introduced in 2011 and the use of this drug was to lower LDL levels and as well as increase insulin levels. This drug could have been used to treat metabolic syndrome but was removed from the market by Merck in 2013 due to business reasons.

High-dose statins, recommended to reduce cardiovascular risk, have been associated with higher progression to diabetes, particularly in patients with metabolic syndrome. The biological mechanisms are not entirely understood, however, the plausible explanation may lie in competitive inhibition of glucose transport via the solute carrier (SLC) family of transporters (specifically "SLCO1B1"), important in statin pharmacokinetics.

Some studies on mice suggest that a Time Restricted Diet (TRD) could be helpful in reversing obesity and possibly metabolic syndrome

The World Health Organization (WHO) recommends rehydrating a severely undernourished child who has diarrhea relatively slowly. The preferred method is with fluids by mouth using a drink called oral rehydration solution (ORS). The oral rehydration solution is both slightly sweet and slightly salty and the one recommended in those with severe undernutrition should have half the usual sodium and greater potassium. Fluids by nasogastric tube may be use in those who do not drink. Intravenous fluids are recommended only in those who have significant dehydration due to their potential complications. These complications include congestive heart failure. Over time, ORS developed into ORT, or oral rehydration therapy, which focused on increasing fluids by supplying salts, carbohydrates, and water. This switch from type of fluid to amount of fluid was crucial in order to prevent dehydration from diarrhea.

Breast feeding and eating should resume as soon as possible. Drinks such as soft drinks, fruit juices, or sweetened teas are not recommended as they contain too much sugar and may worsen diarrhea. Broad spectrum antibiotics are recommended in all severely undernourished children with diarrhea requiring admission to hospital.

To prevent dehydration readily available fluids, preferably with a modest amount of sugars and salt such as vegetable broth or salted rice water, may be used. The drinking of additional clean water is also recommended. Once dehydration develops oral rehydration solutions are preferred. As much of these drinks as the person wants can be given, unless there are signs of swelling. If vomiting occurs, fluids can be paused for 5–10 minutes and then restarting more slowly. Vomiting rarely prevents rehydration as fluid are still absorbed and the vomiting rarely last long. A severely malnourished child with what appears to be dehydration but who has not had diarrhea should be treated as if they have an infection.

For babies a dropper or syringe without the needle can be used to put small amounts of fluid into the mouth; for children under 2, a teaspoon every one to two minutes; and for older children and adults, frequent sips directly from a cup. After the first two hours, rehydration should be continued at the same or slower rate, determined by how much fluid the child wants and any ongoing diarrheal loses. After the first two hours of rehydration it is recommended that to alternate between rehydration and food.

In 2003, WHO and UNICEF recommended a reduced-osmolarity ORS which still treats dehydration but also reduced stool volume and vomiting. Reduced-osmolarity ORS is the current standard ORS with reasonably wide availability. For general use, one packet of ORS (glucose sugar, salt, potassium chloride, and trisodium citrate) is added to one liter of water; however, for malnourished children it is recommended that one packet of ORS be added to two liters of water along with an extra 50 grams of sucrose sugar and some stock potassium solution.

Malnourished children have an excess of body sodium. Recommendations for home remedies agree with one liter of water (34 oz.) and 6 teaspoons sugar and disagree regarding whether it is then one teaspoon of salt added or only 1/2, with perhaps most sources recommending 1/2 teaspoon of added salt to one liter water.

Treating malnutrition, mostly through fortifying foods with micronutrients (vitamins and minerals), improves lives at a lower cost and shorter time than other forms of aid, according to the World Bank. The Copenhagen Consensus, which look at a variety of development proposals, ranked micronutrient supplements as number one.

In those with diarrhea, once an initial four-hour rehydration period is completed, zinc supplementation is recommended. Daily zinc increases the chances of reducing the severity and duration of the diarrhea, and continuing with daily zinc for ten to fourteen days makes diarrhea less likely recur in the next two to three months.

In addition, malnourished children need both potassium and magnesium. This can be obtained by following the above recommendations for the dehydrated child to continue eating within two to three hours of starting rehydration, and including foods rich in potassium as above. Low blood potassium is worsened when base (as in Ringer's/Hartmann's) is given to treat acidosis without simultaneously providing potassium. As above, available home products such as salted and unsalted cereal water, salted and unsalted vegetable broth can be given early during the course of a child's diarrhea along with continued eating. Vitamin A, potassium, magnesium, and zinc should be added with other vitamins and minerals if available.

For a malnourished child with diarrhea from any cause, this should include foods rich in potassium such as bananas, green coconut water, and unsweetened fresh fruit juice.

Although the etiology is unconfirmed, transient hyperammonemia is known to be caused by increased levels of ammonia in the blood stream, as well as a failure of the urea cycle to convert enough of the ammonia into urea. Since transamination of proteins is a leading producer of ammonia, protein restriction may be recommended as a therapy to reduce the symptoms of the episode. THAN can also be treated by avoiding amino acids in TPN or total parenteral nutrition or by giving a high caloric diet to limit catabolism of the tissues and therefore to minimize the breakdown of endogenous protein. The most common treatments are dialysis (both peritoneal and hemodialysis), sodium benzoate, and arginine. Sodium Benzoate combines with glycine to be excreted in the form of hippuric acid. The goal of these treatments is to convert nitrogen to a compound that can be excreted more easily.

Carotenemia and carotenoderma is in itself harmless, and does not require treatment. In primary carotenoderma, when the use of high quantities of carotene is discontinued the skin color will return to normal. It may take up to several months, however, for this to happen. Infants with this condition should not be taken off prescribed vitamin supplements unless advised to do so by the child's pediatrician.

As to underlying disorders in secondary carotinemia and carotenoderma, treatment depends wholly on the cause.

Treatment with antibiotics such as amoxicillin or cefdinir improve the response and survival rate of severely malnourished children to an outpatient treatment plan which provided therapeutic food. This confirms the recommendation, "In addition to the provision of RUTF [ready-to-use therapeutic food], children need to receive a short course of basic oral medication to treat infections." contained in "Community-based management of severe acute malnutrition, A Joint Statement by the World Health Organization, the World Food Programme, the United Nations System Standing Committee on Nutrition and the United Nations Children’s Fund."

Many people with beriberi can be treated with thiamine alone. Given thiamine intravenously (and later orally), rapid and dramatic recovery can occur within hours. In situations where concentrated thiamine supplements are unavailable, feeding the person with a thiamine-rich diet (e.g. whole grain brown bread) will lead to recovery, though at a much slower rate.

Following thiamine treatment, rapid improvement occurs, in general, within 24 hours. Improvements of peripheral neuropathy may require several months of thiamine treatment.

Novel zinc biomarkers, such as the erythrocyte LA:DGLA ratio, have shown promise in pre-clinical and clinical trials and are being developed to more accurately detect dietary zinc deficiency.

The mortality rate for THAN is relatively high unless immediate treatment is obtained. The duration of hyperammonemia is directly correlated to morbidity as well as the associated neurological conditions. After the first hyperammonemic episode, there is no increased risk for future hyperammonemic episodes, and normal protein consumption can be continued.

Available treatments address the symptoms of CCD, not the underlying defect. Early diagnosis and aggressive salt replacement therapy result in normal growth and development, and generally good outcomes. Replacement of NaCl and KCl has been shown to be effective in children.

A potential treatment is butyrate.

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.

Medical treatment can directly or indirectly cause weight loss, impairing treatment effectiveness and recovery that can lead to further weight loss in a vicious cycle.

Many patients will be in pain and have a loss of appetite after surgery. Part of the body's response to surgery is to direct energy to wound healing, which increases the body's overall energy requirements. Surgery affects nutritional status indirectly, particularly during the recovery period, as it can interfere with wound healing and other aspects of recovery. Surgery directly affects nutritional status if a procedure permanently alters the digestive system. Enteral nutrition (tube feeding) is often needed. However a policy of 'nil by mouth' for all gastrointestinal surgery has not been shown to benefit, with some suggestion it might hinder recovery.

Early post-operative nutrition is a part of Enhanced Recovery After Surgery protocols. These protocols also include carbohydrate loading in the 24 hours before surgery, but earlier nutritional interventions have not been shown to have a significant impact.

Some medications can cause weight loss, while others can cause weight gain.

Various strategies have been proposed to prevent the development of metabolic syndrome. These include increased physical activity (such as walking 30 minutes every day), and a healthy, reduced calorie diet. Many studies support the value of a healthy lifestyle as above. However, one study stated these potentially beneficial measures are effective in only a minority of people, primarily due to a lack of compliance with lifestyle and diet changes. The International Obesity Taskforce states that interventions on a sociopolitical level are required to reduce development of the metabolic syndrome in populations.

The Caerphilly Heart Disease Study followed 2,375 male subjects over 20 years and suggested the daily intake of a pint (~568 ml) of milk or equivalent dairy products more than halved the risk of metabolic syndrome. Some subsequent studies support the authors' findings, while others dispute them. A systematic review of four randomized controlled trials found that a paleolithic nutritional pattern improved three of five measurable components of the metabolic syndrome in participants with at least one of the components.