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.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. Malnutrition can affect every function of the human body, from the cells to the most complex body functions, including:
immune response;
wound healing;
muscle strength (including respiratory muscles);
renal capacity and depletion leading to water and electrolyte disturbances;
thermoregulation; and
menstruation.Malnutrition can lead to vitamin and other deficiencies and to inactivity, which in turn may pre-dispose to other problems, such as pressure sores. Unintentional weight loss can be the characteristic leading to diagnosis of diseases such as cancer and type 1 diabetes. 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. According to data in the UK using the Malnutrition Universal Screening Tool (MUST), which incorporates unintentional weight loss, more than 10% of the population over the age of 65 is at risk of malnutrition. A high proportion (10–60%) of hospital patients are also at risk, along with a similar proportion in care homes. Causes
Disease-related
Disease-related malnutrition can be considered in four categories:
Weight loss issues related to specific diseases include:

As chronic obstructive pulmonary disease (COPD) advances, about 35% of patients experience severe weight loss called pulmonary cachexia, including diminished muscle mass.
Myths
Some popular beliefs attached to weight loss have been shown to either have less effect on weight loss than commonly believed or are actively unhealthy. According to Harvard Health, the idea of metabolic rate being the "key to weight" is "part truth and part myth" as while metabolism does affect weight loss, external forces such as diet and exercise have an equal effect. They also commented that the idea of changing ones rate of metabolism is under debate. Diet plans in fitness magazines are also often believed to be effective but may actually be harmful by limiting the daily intake of important calories and nutrients which can be detrimental depending on the person and are even capable of driving individuals away from weight loss. Health effects
Obesity increases health risks, including diabetes, cancer, cardiovascular disease, high blood pressure, and non-alcoholic fatty liver disease, to name a few. Reduction of obesity lowers those risks. A 1-kg loss of body weight has been associated with an approximate 1-mm Hg drop in blood pressure. Intentional weight loss is associated with cognitive performance improvements in overweight and obese individuals. See also
Anorexia
Cigarette smoking for weight loss
Dieting
Physical exercise
Weight gain

References
External links

Weight loss  at Curlie
Health benefits of losing weight By IQWiG at PubMed Health
Weight-control Information Network Archived 12 February 2015 at the Wayback Machine  U.S. National Institutes of Health
Nutrition in cancer care By NCI at PubMed Health
Unintentional weight loss