Involuntary weight loss refers to weight loss that occurs when a person is not on a diet or trying to lose weight. As everyone’s weight increases or falls over time (as during an illness), doctors generally care only about people who lose more than 4 kg to 5 kg (about 10 pounds) or, in smaller people, 5 % of your body weight. This weight loss can be a sign of a serious physical or mental disorder. In addition to weight loss, the person may have other symptoms, such as loss of appetite, fever, pain or night sweats, due to an underlying disorder.
Too often, weight loss occurs because a person consumes fewer calories than his or her body needs. The person may eat fewer calories because he or she has a decreased appetite or because he has a disorder that prevents the digestive tract from absorbing nutrients (called malabsorption ). Less often, the person has a disorder that causes him to use more calories (for example, an overactive thyroid gland). Sometimes, both mechanisms are involved. For example, cancer tends to decrease appetite, but it also increases calorie expenditure, leading to rapid weight loss.
Almost any disease of long duration and of sufficient severity can cause weight loss (for example, severe heart failure or emphysema). However, these disorders have usually been diagnosed by the time that weight loss has occurred. This discussion focuses on weight loss as the first sign of illness. The causes can be divided between people who have an increased appetite, and those of people who have a loss of appetite.
With increased appetite , the most common unrecognized causes of involuntary weight loss are
- An overactive thyroid gland ( hyperthyroidism )
- Uncontrolled diabetes
- Disorders that cause malabsorption
With decreased appetite , the most common unrecognized causes of involuntary weight loss are
- Mental disorders (eg, depression )
- Side effects of medications
- Drug abuse
The following information can help people decide when a medical evaluation is needed and what to expect during the evaluation.
Because many disorders can cause involuntary weight loss, the doctor usually needs to do a thorough evaluation.
In people with involuntary weight loss, certain symptoms and characteristics are of concern. Include
- Fever and night sweats
- Bone pain
- Shortness of breath, cough and bloody cough
- Excessive thirst and increased urinary frequency
- Headache, jaw pain when chewing and / or new vision disorders (for example, double vision, blurred vision or blind spots) in a person over 50
When to see a doctor
People who have warning signs should see a doctor immediately. People who do not show warning signs should see a doctor as soon as possible. In general, a week’s delay or something similar is not harmful.
What the doctor does
First, the doctor asks questions about the symptoms and medical history. Then the doctor does a physical exam. What he identifies in the history and during the physical examination often suggests a cause for weight loss and the tests that may be needed (see the table Some common causes and characteristics of involuntary weight loss ).
The doctor first asks how much weight the person has lost over a period of time. The doctor may ask about
- Changes in clothing size, appetite and food intake
- If the person has difficulty swallowing
- If bowel patterns have changed
- What other symptoms does the person have, such as fatigue, malaise, fevers and night sweats
- If the person has a history of a disorder that causes weight loss
- What medications, including prescription drugs, over-the-counter and recreational drugs, as well as herbal products, is the person using
- If there have been changes in the person’s life situation (for example, the loss of a loved one, loss of independence or job, loss of a communal meal routine)
During the physical examination, the doctor checks vital signs, measures the temperature, checks the heartbeat, if breathing is fast and if blood pressure is low. The general physical examination is very complete because many disorders can cause involuntary weight loss. The doctor examines the heart, lungs, abdomen, head and neck, breasts, nervous system, rectum (including a prostate exam in men and tests for blood in the stool), genitals, liver, the spleen, lymph nodes, joints and skin. The doctor also assesses the person’s mood.
Weight is measured and the body mass index is calculated .
People’s symptoms and the doctor’s findings during physical examination suggest the cause of weight loss in approximately 50% of people, including many people who end up being diagnosed with cancer.
Screening is often done for common cancers (for example, colonoscopy for colon cancer or mammography for breast cancer). Other tests are performed, depending on what disorders the doctor suspects. When the history and physical examination do not suggest specific causes, some doctors do a series of tests, including chest X-rays, blood tests and urinalysis, to try to find out the cause. These exams are followed by more specific exams, if necessary.
If the results of all tests are normal, the doctor will usually reevaluate the person after a few months to see if new symptoms or findings have emerged.
The underlying disorder is treated. To help the person eat more, the doctor usually tries to use behavioral measures, such as encouraging the person to eat, helping them with meals, offering favorite foods or foods with a strong flavor, and offering only small portions. If behavioral measures are ineffective, highly nutritious food supplements can be tested. Feeding through a tube inserted into the stomach is a last resort, and is only valid in certain specific situations. For example, tube feeding may be valid if the person has a disorder that will be cured or resolved, but it may not be worth it if the person stops eating because of severe Alzheimer’s disease.
Essential information for the elderly: Involuntary weight loss
The incidence of involuntary weight loss increases with aging, usually reaching 50% among nursing home residents. The elderly are more likely to have involuntary weight loss, because the disorders that can cause weight loss are more common among them. There are also normal age-related changes that contribute to weight loss. Generally, many factors are involved.
The normal age-related changes that can contribute to weight loss include the following:
- Reduced sensitivity to certain appetite-stimulating mediators, and increased sensitivity to certain appetite-inhibiting mediators
- A reduced rate of gastric emptying (prolonged feeling of fullness)
- Reduced sensitivities to taste and smell
- Loss of muscle mass (sarcopenia)
In addition, social isolation is common in the elderly, which tends to reduce food intake. Depression and dementia are very common contributing factors, particularly among nursing home residents. It is often difficult to discover the exact contribution of specific factors.
Elderly people may benefit from nutritional supplements to correct vitamin deficiencies (for example, vitamin D and B12 ). However, supplements should be administered between meals and at bedtime. Otherwise, supplements may decrease appetite at mealtime. Helping with food and shopping can also help some people.