What is Weight loss ?
 
 Unintentional weight loss  is a decrease in body weight that is not voluntary. In other words, you  did not try to loss the weight by dieting or exercising. 
 Any condition in  which you lose your appetite for an extended period of time—a chronic  illness like cancer, for example—can strip you of pounds. One of the  most common of these anti-appetite diseases is a chronic infection. 
 
 What are the main causes of weight loss?
 
 AIDS
 Cancer 
 Depression 
 Diarrhea that is chronic (lasts a long time)
 Drugs, including amphetamines, chemotherapeutic agents, laxative abuse, and thyroid medications
 Drug abuse
 Eating disorders, including anorexia nervosa and bulimia
 Hyperthyroidism
 Infection
 Loss of appetite
 Malnutrition
 Manipulative behavior (in children)
 Painful mouth sores, mouth braces, or a loss of teeth that prevent you from eating normally
 Smoking
 Poor diet 
 Increase in exercise or exertion 
 Dieting
 Starvation
 Neglect 
 Anxiety
 Aging
 Not eating enough 
 Meal preparation or shopping difficulty - such as in the elderly 
 Denture difficulties 
 Loss of appetite - see the various causes of loss of appetite
 Athletic training 
 Mental health disorders 
 Eating disorder
 Anorexia nervosa
 Depression
 Clinical depression
 Grief
 Loss of appetite
 Anxiety
 Certain psychiatric disorders 
 Substance-related possible causes of weight loss include: 
 Alcohol abuse
 Drug abuse
 Amphetamines- cause appetite suppression leading to weight loss.
Some possible digestive condition causing weight loss-Chronic digestive infection 
 Inflammatory bowel disease
 Stomach ulcer
 Weight loss due to gastrointestinal or digestive diseases and disorders
 Losing weight due to old age
 
 Beside this there are some another reasons of weight loss:
 
 Hyperthyroidism causing weight loss
 
 When the thyroid gland overproduces certain hormones, unexplained  weight loss may occur. Your doctor can order a simple panel of tests to  determine if an overactive thyroid is the cause of your weight loss.
 
 Medication and a resulting weight loss
 
 Certain types of medication, including some antidepressants, have been  known to cause unexpected weight loss. Read the accompanying packaging  on your prescription medications and talk to your pharmacist or doctor  if you suspect this might be the cause of your weight loss.
 
 Some more causes of weight loss can be described as:
 
 • digestive diseases, such as inflammatory bowel disease or peptic ulcers 
 • hormone imbalances, such as an increased thyroid hormone level known as hyperthyroidism 
 • increased level of physical activity, due to exercise or manual labor 
 • infections, such as HIV or tuberculosis 
 • intake of fewer calories 
 • medicine or drugs, such as amphetamines, ephedrine, cocaine, heroin, or alcohol 
 • psychiatric conditions, such as depression, anorexia, or schizophrenia 
 • severe kidney, liver, or heart disease.
 • conditions that affect the ability of the intestines to absorb food and other nutrients 
 • diabetes, a condition that results in high blood glucose levels 
