Any form of decreased appetite that leads to changes in the body (such as weight loss or muscle loss) that is not done intentionally as part of dieting is clinically significant. Physiology of anorexia
Appetite stimulation and suppression is a complex process involving many different parts of the brain and body by the use of various hormones and signals. Appetite is thought to be stimulated by interplay between peripheral signals to the brain (taste, smell, sight, gut hormones) as well as the balance of neurotransmitters and neuropeptides  in the hypothalamus. Examples of these signals or hormones include neuropeptide Y, leptin, ghrelin, insulin, serotonin, and orexins (also called hypocretins). Anything that causes an imbalance of these signals or hormones can lead to the symptom of anorexia. While it is known that these signals and hormones help control appetite, the complicated mechanisms regarding a pathological increase or decrease in appetite are still being explored. Common causes
Acute radiation syndrome
Addisons disease
Alcoholism
Alcohol withdrawal
Anemia
Anorexia nervosa
Anxiety
Appendicitis
Babesiosis
Benzodiazepine withdrawal
Bipolar disorder
Cancer
Cannabinoid hyperemesis syndrome
Cannabis withdrawal
Celiac disease
Chronic kidney disease
Chronic pain
Common cold
Constipation
COPD
COVID-19
Crohns disease
Dehydration
Dementia
Depression
Ebola
Fatty liver disease
Fever
Food poisoning
Gastroparesis
Hepatitis
HIV/AIDS
Hypercalcemia
Hyperglycemia
Hypervitaminosis D
Hypothyroidism and sometimes hyperthyroidism
Irritable bowel syndrome
Ketoacidosis
Kidney failure
Low blood pressure
Mania
Metabolic disorders, particularly urea cycle disorders
MELAS syndrome
Nausea
Opioid use disorder
Pancreatitis
Pernicious anemia
Psychosis
Schizophrenia
Side effect of drugs
Stimulant use disorder
Stomach flu
Stress
Sickness behavior
Superior mesenteric artery syndrome
Syndrome of inappropriate antidiuretic hormone secretion
Tuberculosis
Thalassemia
Ulcerative colitis
Uremia
Vitamin B12 deficiency
Zinc deficiency
Infection: Anorexia of infection is part of the acute phase response (APR) to infection. The APR can be triggered by lipopolysaccharides and peptidoglycans from bacterial cell walls, bacterial DNA, and double-stranded viral RNA, and viral glycoproteins, which can trigger production of a variety of proinflammatory cytokines.
Osteochondropathy refers to a disease ("-pathy") of the bone and cartilage. However, it is more common to refer to these conditions as one of the following:

chondropathy (disease of the cartilage)
A bone disease is also called an "osteopathy", but because the term osteopathy is often used to describe a healthcare approach, use of the term can cause some confusion. See also
Osteochondrosis
Osteochondritis

References


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