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By now you know intentional weight loss is nearly impossible. So what are you supposed to think when your weight starts dropping and you aren’t even trying?

Many things can cause unexplained weight loss, and some of them are pretty serious. A 2018 study found that 60 percent of unexplained weight loss cases are due to physical causes, with cancer being the most common physical cause. It’s definitely not a symptom to ignore.

Men vs. women

Weirdly enough, some causes of unintentional weight loss affect men or women disproportionately. Here’s a breakdown of causes that men are at higher risk of developing:

And women are more likely to develop these conditions that cause weight loss:

Check your stats and call the doctor — stat!

Scientists don’t totally agree on how much is too much, but the most commonly recognized threshold for “clinically significant” weight loss is a decrease of 5 percent (or more) body weight in 6 to 12 months.

If you’ve lost that much weight without trying, it’s a good time to make note of other symptoms and give your healthcare provider a call.

Appetite loss is a common symptom of depression. A 2018 study showed that depressed patients with reduced appetite also had higher cortisol levels.

According to the National Institute of Mental Health, these are the symptoms of depression:

  • lasting feelings of sadness, anxiety, or emptiness
  • hopelessness or pessimism
  • irritability
  • feeling guilty or worthless
  • loss of interest in activities you typically enjoy
  • fatigue or lack of energy
  • sluggishness in movement or speech
  • restlessness
  • trouble with concentration, memory, or decision making
  • sleeping too much or too little
  • changes in weight or appetite
  • thoughts of death or suicide, or suicide attempts
  • unexplained pain, headaches, or digestive problems that don’t improve, even with treatment

For a diagnosis of depression, symptoms must be present most of the day, nearly every day, for at least 2 weeks. Depression is usually treated with medication, psychotherapy, or both.

When the thyroid gland is overactive (aka hyperthyroidism), it produces excess hormones that increase metabolism and lead to weight loss.

Other symptoms of hyperthyroidism are nervousness, irritability, fatigue, muscle weakness, heat intolerance, difficulty sleeping, shaky hands, rapid or irregular heartbeat, diarrhea, and mood changes.

Hyperthyroidism is treated with medication, radioiodine therapy, and sometimes surgery.

Diabetes is a chronic condition defined by too much glucose in the blood, either because your body doesn’t produce enough insulin or because your body doesn’t use it properly.

In addition to weight loss, symptoms of diabetes include an increase in hunger and/or thirst, fatigue, blurry vision, numbness or tingling in hands and feet, and sores that don’t heal.

The primary treatment for diabetes is insulin or other medication. In type 2 diabetes, diet and exercise changes and stress management can also help regulate blood sugar levels.

Inflammatory bowel disease (IBD) describes two conditions of the gastrointestinal tract: Crohn’s disease and ulcerative colitis. Research indicates that about half of people with these conditions experience significant weight loss (more than 5 percent of their BMI) before diagnosis.

Both conditions are inflammatory, can increase metabolism, and have symptoms that can lead to food avoidance and malnutrition.

Aside from weight loss, common symptoms include diarrhea, abdominal pain, bloody stools, and fatigue. Treatment may include medication, vaccinations, and — less commonly — surgery to remove damaged parts of the GI tract.

Many medications have loss of appetite or weight loss as a side effect, and multiple medications taken together can change a person’s sense of taste and affect their appetite.

Here are some appetite-related adverse effects and the medications that may cause them:

  • Changes in taste or smell: Allopurinol, angiotensin-converting enzyme inhibitors, antibiotics, anticholinergics, antihistamines, calcium channel blockers, levodopa, propranolol, selegiline (Eldypryl), spironolactone (Aldactone)
  • Loss of appetite: Amantadine, antibiotics, anticonvulsants, antipsychotics, benzodiazepines, digoxin, levodopa, metformin (Glucophage), neuroleptics, opiates, SSRIs, theophylline
  • Dry mouth: Anticholinergics, antihistamines, clonidine (Catapres), loop diuretics
  • Difficulty swallowing: Bisphosphonates, doxycycline, gold, iron, nonsteroidal anti-inflammatory drugs, potassium
  • Nausea and vomiting: Amantadine, antibiotics, bisphosphonates, digoxin, dopamine agonists, metformin, SSRIs, statins, tricyclic antidepressants

If you have celiac disease, your body has an immune reaction to gluten, a protein in wheat, barley, and rye. According to the American College of Gastroenterology, celiac disease symptoms include weight loss, diarrhea, bloating, gas, and abdominal pain.

Celiac disease may also cause liver problems, iron deficiency, bone disease, and skin conditions. Typically, removing gluten from your diet is enough to avoid symptoms.

Alcohol and drug consumption can affect your body’s ability to absorb nutrients. Drugs like methamphetamine, cocaine, and opiates are appetite suppressants. They can also cause metabolic and gastrointestinal problems that contribute to weight loss.

“Cachexia” is the medical term for muscle loss or “wasting.” When muscles atrophy or shrink, proteins in the muscle tissue are being consumed by the body.

Cachexia is a symptom of myopathies, muscular dystrophy, cancer, diabetes, sepsis, and heart failure. Muscle loss is also associated with aging. Treatment depends on the underlying cause.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that causes chronic joint pain. Research shows that people with RA who have the highest percentage of weight loss also have a higher risk of death from cardiovascular causes.

People with RA may lose muscle mass without losing weight — this is called rheumatoid cachexia. A 2018 meta-analysis found that 15 to 32 percent of people with RA experience this.

Tuberculosis, a bacterial infection of the lungs, is associated with loss of appetite and unintended weight loss.

Other symptoms include a cough that lasts 3 weeks or longer, coughing up blood, chest pain, fatigue, fever, night sweats, and chills. The infection can be treated with medication or prevented with vaccines.

Addison’s disease (adrenal insufficiency) is a rare endocrine condition that commonly causes weight loss.

It can be difficult to diagnose because it has symptoms similar to those of many other illnesses. Symptoms may seem to be gastrointestinal and hide the underlying adrenal causes for weight loss.

Other symptoms include:

  • fatigue
  • skin darkening
  • salt craving
  • abdominal pain
  • muscle and joint pain
  • irritability and depression

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease often caused by smoking. Symptoms include coughing, wheezing, and difficulty breathing.

As the disease advances, patients become more undernourished and need a high calorie diet. COPD is treated with medication, respiratory rehabilitation, and nutrition counseling.

Infective endocarditis is a heart infection that affects 12.7 per 100,000 people in the United States every year. Some cases are more likely to cause symptoms like weight loss, fatigue, and difficulty breathing.

Because endocarditis often results from poor dental hygiene, regular brushing and flossing is the best way to prevent it.

A 2018 study found that weight loss can be a predictor of 10 types of cancer:

  • prostate
  • colorectal
  • lung
  • gastroesophageal
  • pancreatic
  • non-Hodgkin’s lymphoma
  • ovarian
  • myeloma
  • renal tract
  • biliary tree (bile duct)

Many forms of cancer lead to weight loss, and cancer treatment is also known for its negative impact on appetite and body weight.

In 2015, an estimated 46.8 million people worldwide were living with dementia. Thirty to 40 percent of people with dementia have clinically significant weight loss, in part because they eat less.

Weight loss can happen before dementia is diagnosed and can be a signal that a person is in cognitive decline.

Many medical conditions can decrease appetite, increase metabolism, or cause muscles to break down, and those factors can add up to unexpected weight loss.

Consider unintended weight loss a signal from your body that something’s wrong. Your healthcare provider can evaluate other symptoms, do blood tests and a physical exam, and use imaging techniques to uncover the issue and find the right treatment for you.