Unintentional weight loss can occur because of an inadequately nutritious diet relative to a person’s energy needs (generally called malnutrition). Disease processes, changes in metabolism, hormonal changes, medications or other treatments, disease- or treatment-related dietary changes, or reduced appetite associated with a disease or treatment can also cause unintentional weight loss.[42][43][44][48][49][50] Poor nutrient utilization can lead to weight loss, and can be caused by fistulae in the gastrointestinal tract, diarrhea, drug-nutrient interaction, enzyme depletion and muscle atrophy.[44]
Continuing weight loss may deteriorate into wasting, a vaguely defined condition called cachexia.[47] Cachexia differs from starvation in part because it involves a systemic inflammatory response.[47] It is associated with poorer outcomes.[42][47][48] In the advanced stages of progressive disease, metabolism can change so that they lose weight even when they are getting what is normally regarded as adequate nutrition and the body cannot compensate. This leads to a condition called anorexia cachexia syndrome (ACS) and additional nutrition or supplementation is unlikely to help.[44] Symptoms of weight loss from ACS include severe weight loss from muscle rather than body fat, loss of appetite and feeling full after eating small amounts, nausea, anemia, weakness and fatigue.[44]
Serious weight loss may reduce quality of life, impair treatment effectiveness or recovery, worsen disease processes and be a risk factor for high mortality rates.[42][47] Malnutrition can affect every function of the human body, from the cells to the most complex body functions, including:[46]
immune response;
wound healing;
muscle strength (including respiratory muscles);
renal capacity and depletion leading to water and electrolyte disturbances;
thermoregulation; and
menstruation.
In addition, malnutrition can lead to vitamin and other deficiencies and to inactivity, which in turn may pre-dispose to other problems, such as pressure sores.[46]
Unintentional weight loss can be the characteristic leading to diagnosis of diseases such as cancer[42] and type 1 diabetes.[51]
In the UK, up to 5% of the general population is underweight, but more than 10% of those with lung or gastrointestinal diseases and who have recently had surgery.[46] According to data in the UK using the Malnutrition Universal Screening Tool (‘MUST’), which incorporates unintentional weight beli pulsa via paypal loss, more than 10% of the population over the age of 65 is at risk of malnutrition.[46] A high proportion (10–60%) of hospital patients are also at risk, along with a similar proportion in care homes.