Weight Loss- It’s Main Causes

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