Weight loss occurs when a person burns more calories, or energy, than he or she takes in. It may be deliberate or unintentional.
A loss of weight is due to one of three factors: fewer calories are consumedmore calories or energy are burned off during activitya person's basic resting metabolism speeds up
Weight loss may or may not be intended. Unplanned weight loss is often a sign of serious illness.
Weight loss through physical activity and eating a proper diet should not cause concern. Rather, the person usually feels healthier. Intentional weight loss through unhealthy means, such as smoking or misuse of diuretics, causes other health consequences.
Unintended weight loss is a cause for concern. In this setting, the healthcare professional will need more information, such as: How much weight has been lost?When did the weight loss start?Has the person's appetite or thirst level changed?Has the person's diet changed?Has the person's activity level changed?Has there been a change in the person's bladder or bowel habits?Has the person's mood changed?What medicines, drugs, herbs, or other substances is the person taking?What other medical conditions does the person have?Are there any other symptoms, such as fever or weakness?
Some of the causes of weight loss are as follows: cancer, including colon cancer, lung cancer, cancer of the pancreas, or leukemiaconditions that affect the ability of the intestines to absorb food and other nutrientsdiabetes, a condition that results in high blood glucose levelsdigestive diseases, such as inflammatory bowel disease or peptic ulcershormone imbalances, such as an increased thyroid hormone level known as hyperthyroidismincreased level of physical activity, due to exercise or manual laborinfections, such as HIV or tuberculosisintake of fewer caloriesmedicine or drugs, such as amphetamines, ephedrine, cocaine, heroin, or alcoholpsychiatric conditions, such as depression, anorexia, or schizophreniasevere kidney, liver, or heart disease
Other causes of weight loss are also possible. Sometimes a cause cannot be found.
For unintended weight loss, prevention is related to the cause. Avoiding the drugs that cause weight loss could prevent those cases due to drugs. Practicing safest sex can nearly eliminate the risk of sexually-transmitted HIV infection. Practicing safer sex can reduce, but not eliminate, cases due to sexually-transmitted HIV infection. Many cases of unintended weight loss cannot be prevented.
In some cases, the cause of the weight loss is obvious from the medical history and a physical exam. In other cases, further tests are needed. Blood and urine tests may be ordered to diagnose underlying health problems. X-ray tests may be done, such as a chest X-ray to look for heart or lung disease. An abdominal CT scan can be used to look for cancer of the pancreas or liver.
Intentional weight loss from a healthy diet and exercise decreases the risk of: blood clots, such as deep venous thrombosescancerdeathdiabetesgallstonesheart diseasehigh blood pressureosteoarthritis, which is also called wear and tear arthritis, the most common type of arthritisvaricose veins, which are enlarged veins often seen in the legs
Intentional weight loss through smoking can cause all the heart, lung, and other negative health consequences of tobacco use. Misuse of diuretics can cause dehydration with all its resulting consequences. Intentional weight loss that is part of an eating disorder such as anorexia nervosa can cause illness in nearly every body system, and is sometimes fatal if not successfully treated.
The long-term effects of unintentional weight loss are related to the cause. Cancer, diabetes, HIV, and severe heart, liver, or kidney disease are common causes of death. Many people who abuse drugs have long-term effects related to social, legal, and psychological problems from the drug abuse.
Weight loss is not contagious. If infection is the cause of unintended weight loss, however, the infection may be contagious. HIV, for example, can be sexually transmitted. Tuberculosis can be spread through respiratory secretions.
Weight management plans are helpful for obese or overweight people who want to lose weight.
Treatment for unintended weight loss is directed at the cause. For example, a person with diabetes may need insulin injections or other medicines to control his or her blood glucose levels. Someone who is abusing drugs may need to enter a rehabilitation program. An individual with an infection may need antibiotics. A person with cancer may need surgery, chemotherapy, or radiation therapy.
Side effects depend on the treatment used for weight loss. Medicines may cause allergic reactions or stomach upset. Surgery can be complicated by bleeding, infection, or allergic reactions to anesthetic.
A person who loses weight from diet and exercise often feels healthier and happier. Someone with unintentional weight loss may be cured by treatment, such a person with depression. Others may die, such as those with advanced cancer, HIV, or severe liver disease.
Weight can be monitored at home and at every visit to the healthcare professional. Further monitoring is related to the cause. For example, a person with diabetes needs frequent blood tests to monitor his or her blood glucose level. Any new or worsening symptoms should be reported to the healthcare professional.
Harrison's Principles of Internal Medicine, 1998, Fauci et al.