Anorexia is a medical term for a loss of appetite.
It is often used interchangeably with anorexia nervosa, many possible causes exist for a loss of appetite, some of which may be harmless, while others indicate a serious clinical condition or pose a significant risk.
Anorexia is not wanting to eat, no hunger, dizziness, weakness
Anorexia is a symptom, not a diagnosis.
Anorexia manifests as a decreased or loss of appetite, presenting as not feeling hungry or lacking the desire to eat.
Any form of decreased appetite that leads to changes in the body with weight loss or muscle loss, that is not done intentionally as part of dieting is clinically significant.
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 stimulated by interplay between signals to the brain-taste, smell, sight, gut hormones, as well as the influence of neurotransmitters and neuropeptides in the hypothalamus.
Some of these signals or hormones include neuropeptide Y, leptin, ghrelin, insulin, serotonin, and orexins.
Any imbalance of these signals or hormones can lead to the symptom of anorexia.
Common causes of anorexia:
Acute radiation syndrome ADHD Addison’s disease Alcoholism Alcohol withdrawal Anemia Anorexia nervosa Anxiety Appendicitis Babesiosis Benzodiazepine withdrawal Bipolar disorder Bronchitis Cancer Cannabinoid hyperemesis syndrome Cannabis withdrawal Celiac disease Chronic kidney disease Chronic pain Common cold Constipation COPD COVID-19 Crohn’s disease Cystic fibrosis Dehydration Dementia Depression Diabetes Ebola Fatty liver disease Fever Food poisoning Gastroparesis Heart failure Hepatitis HIV/AIDS Hypercalcemia Hyperglycemia Hypervitaminosis D Hypothyroidism and sometimes hyperthyroidism Irritable bowel syndrome Ketoacidosis Kidney failure Low blood pressure Macroglossia Mania Metabolic disorders, particularly urea cycle disorders MELAS syndrome Nausea Old age Opioid use disorder Pancreatitis Pernicious anemia (vitamin B12 deficiency) Pneumonia Psychosis Schizophrenia Side effect of drugs Stimulant use disorder Stomach flu Stress Sickness behavior Superior mesenteric artery syndrome Syndrome of inappropriate antidiuretic hormone secretion Tobacco smoking Tuberculosis Thalassemia Ulcerative colitis Uremia Folate deficiency Zinc deficiency
Anorexia due to infection is part of the acute phase response (APR) to infection.
The acute phase response 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.
Inflammatory cytokines can enhancing production of leptin from fat stores, and signal to the central nervous system more directly by specialized transport mechanisms through the blood–brain barrier, via circumventricular organs or by triggering production of eicosanoids in the endothelial cells of the brain vasculature.
The control of appetite by this mechanism is thought to be mediated by the same factors normally controlling appetite, such as neurotransmitters (serotonin, dopamine, histamine, norepinephrine, corticotropin releasing factor, neuropeptide Y, and α-melanocyte-stimulating hormone).
Anorectic stimulants:
Stimulants, such as ephedrine, amphetamine, methamphetamine, MDMA, cathinone, methylphenidate, cocaine.
Hormones which are produced by adrenal glands and used as medication such as adrenaline.
Narcotics, such as heroin, morphine, codeine, hydrocodone, oxycodone
Antidepressants may have anorexia as a side effect, primarily selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine.
Byetta, a type II diabetes drug, will cause moderate nausea and loss of appetite.
Abruptly stopping appetite-increasing drugs, such as cannabis and corticosteroids.
Chemicals that are members of the phenethylamine group.
Topiramate may cause anorexia as a side effect.
Other drugs may be used to intentionally cause anorexia.
Allergy
Altitude sickness
Airsickness
Emotional pain caused by an event (rather than a mental disorder) can cause an individual to temporarily lose all interest in food.
Psychological stress
Toothache
Experiencing unpleasant or unappealing thoughts or conversations, and environments
Complications of anorexia:
Poor food intake can lead to dehydration, electrolyte imbalances, anemia and nutritional deficiencies.
Anorexia is a relatively common condition that can lead patients to have dangerous electrolyte imbalances, leading to acquired long QT syndrome which can result in sudden cardiac death.
This can develop over a prolonged period of time, and the risk is further heightened when feeding resumes after a period of abstaining from consumption.
Refeeding syndrome can occur when a patient begins to eat after prolonged starvation to avoid the potentially fatal complications of refeeding syndrome.
The reinitiation of food or oral intake is usually started slowly and requires close observation under supervision by trained healthcare professionals.
This is usually done in a hospital or nutritional rehabilitation center.
Anorexia can be treated with the help of orexigenic drugs.