Cachexia (/kəˈkɛksiə/[1]) is a syndrome that happens when people have certain illnesses, causing muscle loss that cannot be fully reversed with improved nutrition.

[11] Since there are no clear rules separating these conditions, experts continue working to agree on definitions to help treat these nutrition-related problems.

[3] Cachexia should be viewed as a type of malnutrition in which inflammation from a long-term illness causes unwanted muscle loss.

[12] The difference is sarcopenia is caused by aging, while cachexia happens due to long-term disease and inflammation.

[5] Certain molecules in the body, called Inflammatory cytokines, play a big role in causing cachexia.

Tumors sometimes release molecules that break down fat and muscle, causing cachexia by making it harder for the body to keep up with energy needs.

People with cachexia can have loss of appetite, are less responsive to insulin, and can have increased fat breakdown, all of which make it difficult for the body to properly use food.

[19][20] Inflammation may disrupt these appetite signals, causing reduced hunger and leading to further weight and muscle loss.

Factors like fluid buildup (edema), tumor size, and obesity can make it difficult to diagnose cachexia.

[7] Acute phase reactants (IL-6, IL-1b, tumor necrosis factor, IL-8, interferon gamma and serum cytokines are also studied but are not always reliable for predicting cachexia.

Some imaging techniques that can help assess body composition include: However, these methods are not widely used because they can be expensive and difficult to access.

[25] Because cachexia is a complex condition with several potential causes, treatment requires multiple approaches at the same time.

[20] Regular physical exercise is recommended for the treatment of cachexia because of its positive effects on muscle function.

[20] Exercise can reduce protein breakdown, improve muscle strength, decrease inflammation, and enhance metabolism.

[22] Studies show that high-calorie, protein-rich diets may help stabilize weight, though they do not necessarily improve muscle mass.

[20] Progestins showed promise initially, but they do not stop muscle wasting and may cause fluid retention, fat gain, and other side effects.

Selective androgen receptor modulators (SARMs) such as Enobosarm show promise in increasing physical performance and muscle mass, but more studies are needed to confirm their effectiveness in cachexia.

Thalidomide, an anti-inflammatory agent, has shown promise in preventing weight loss, but the use of this medication in cachexia is not widely accepted.

[20] NSAIDs such as celecoxib and ibuprofen showed some early benefits, but side effects (renal injury, GI bleeding) limit their use.

[17] Anabolic steroids like oxandrolone may help but are only recommended for short term use due to side effects including liver toxicity.

Studies show positive results for chronic pulmonary disease, hip fracture, and in AIDS-related and cancer-related cachexia.

[42] Accurate epidemiological data on the prevalence of cachexia is lacking due to changing diagnostic criteria and under-identification of people with the disorder.

[44] Recent updates show that 33%-51.8% of people with cancer develop cachexia, though current estimates of prevalence vary widely and may be unreliable due to absence of consensus guidelines for diagnosis, variability in cancer populations, and variability in timing of diagnosis.

[27] Several medications are under investigation or have been previously trialed for use in cachexia but are currently not in widespread clinical use: Medical marijuana has been allowed for the treatment of cachexia in some US states, such as Missouri, Illinois, Maryland, Delaware, Nevada, Michigan, Washington, Oregon, California, Colorado, New Mexico, Arizona, Vermont, New Jersey, Rhode Island, Maine, and New York [52][53] Hawaii[54] and Connecticut.

[34] Administration of anti-inflammatory drugs showed efficacy and safety in the treatment of people with advanced cancer cachexia.