Unexplained or unintended weight loss should be a signal to you that you need to visit your doctor. Your doctor may become concerned if you experience unintentional weight loss of more than 5% of your usual body weight over a 6 to 12 month period, especially if your weight loss has not stabilized or continues to go down.

For example, a weight loss of 5% in a 160 pound (72 kilograms) person would be equal to a 8 pounds (3.6 kilograms).

There are many causes of weight loss and a clinical exam and testing can often identify the causes. However, in some cases, it’s often difficult to pinpoint an exact cause.

It’s important to have unintended weight loss evaluated as it can be associated with serious medical, mental health or social disorders that can usually be addressed by your healthcare provider.

What is unintentional weight loss?

Unintentional weight loss can be connected to various types of medical conditions, including cancer, gastrointestinal (digestive tract) diseases or psychiatric illness, among others. Lack of adequate nutrition or food can also lead to weight loss, often stemming from a family, financial or social obstacle. Multiple reasons may contribute to weight loss.

Unexpected or unintentional weight loss in children and older adults with chronic diseases can be especially problematic.

Weight loss in older patients is common, estimated to occur in up to 20% of people 65 years of age and older (when followed over at least 10 years).

• In the 12-year U.S. NHANES (National Health and Examination Survey) Mortality Study in 5,000 people over the age of 50, unintentional weight loss was linked to a 24% increase in death, even in people considered obese
• Weight loss in nursing home residents is also associated with increased rates of death. The US Centers for Medicare and Medicaid Services require that long-term care facilities evaluate residents with an unplanned weight loss (5% change in 30 days or 10% change in 180 days).

Weight loss in patients with serious chronic diseases, such as lung disease or heart failure can be associated with higher rates of death. Weight loss in children can also be linked with poor nutrition, lack of food, and school and family environments. 

This overview discusses unintentional weight loss. Weight loss and treatment options for people who are overweight or obese are discussed here.

What are the types of unintentional weight loss?

AIDS Related Wasting - the involuntary loss of body weight due to low appetite, poor nutrient absorption or altered metabolism associated with progression of HIV/AIDS.

Cachexia - involuntary weight loss from loss of muscle mass (with or without fat loss), usually associated with general ill health and malnutrition; can be associated with cancer progression or advanced heart failure.

Failure to Thrive - occurs in children whose current weight or rate of weight gain is significantly lower when compared to other children of the same age and gender.

Sarcopenia - loss of muscle mass, strength and performance in older patients, which may or may not be linked to weight loss.

What causes unintentional weight loss?

The top 4 most common causes for unintentional weight loss are cancer, gastrointestinal (digestive or stomach) disorders, mental health disorders, and unknown or unidentified causes.

• Malignancy (cancer) - seen commonly with lung, gastrointestinal (digestive tract), pancreatic, lymphoma, kidney, and prostate cancer.
• Gastrointestinal disease (non-cancer) - for example, Peptic Ulcer disease (PUD), malabsorption disorders (i.e., Celiac disease), Crohn’s disease or ulcerative colitis.
• Mental health / psychiatric disorders - depression, eating disorders like anorexia nervosa or bulimia nervosa (altered food intake), or other psychiatric illnesses.
• Electrolyte imbalances (high calcium, low sodium)
• Certain medications (eg, digoxin, theophylline, SSRIs, antibiotics) or illicit drugs of abuse (see list below)
• Dental / tooth problems
• Drug or alcohol misuse, addiction
• Endocrine disease - diabetes, especially type 1 diabetes, overactive thyroid (hyperthyroidism), Addison’s disease (adrenal glands don’t make enough cortisol, a natural hormone)
• Infections - bacterial (eg, tuberculosis), viral (eg, HIV / AIDS, hepatitis), fungal (eg, Candidiasis) or parasitic (eg, tapeworm) infections
• Chronic illness - congestive heart failure, lung disease (COPD), or kidney failure
• Brain and nervous system disorders - Parkinson’s disease, Alzheimer’s disease / dementia, stroke (altered cognition), amyotrophic lateral sclerosis (ALS)
• Vigorous exercise - common in long-distance running, ballet, gymnastics
• Severe rheumatoid arthritis

Older adults can present with special problems leading to unintentional weight loss, which can include swallowing problems, depression, anxiety, inability to feed themselves (motor disorder) and tooth loss.

Social isolation can also further worsen depression or anxiety and complicate weight loss. In studies in nursing home patients, weight loss has been associated with depression in 36% of cases.

List of Drugs Associated with Weight Loss