Possible Causes of Involuntary Weight Loss

Dr. Christopher McGowan
June 7, 2022

For most people, weight loss is an important goal, either for aesthetic reasons or as a part of improving overall health. Indeed, with obesity so widespread in the United States, losing weight is a national health imperative. Sometimes, though, weight loss occurs without any apparent cause or even if the person wasn’t even attempting to lose weight. This kind of unexplained weight loss can be a sign of any of a number of underlying health conditions that require medical intervention. 

What Are the Causes of Weight Loss? 

Under normal circumstances, weight loss is only achieved when the body is in a calorie deficit; this means consuming fewer calories from food intake than are expended through normal bodily functions and physical activity. When people are trying to lose weight, they usually adopt a reduced calorie diet or add an exercise regimen to their weekly schedule. And then, depending on the magnitude of the calorie deficit and each person’s unique metabolic properties, the body starts using fat deposits to meet its energy needs. 

What Causes Unintentional Weight Loss?  

The truth is that there are a wide variety of potential causes of unintentional or involuntary weight loss. Studies have suggested that the actions of various hormones and cytokines (proteins involved in cell signaling) may be common to the majority of causes, but more research is needed to understand the specific mechanisms. The process of diagnosing the cause of unintentional weight loss can be difficult, and actually in about 25% of cases no precise cause is able to be identified. 

Because there are so many possible causes, almost anyone can develop some type of condition that has involuntary weight loss as a symptom. It tends to be more common, however, as people become older adults; it is especially prevalent in geriatric patients who live in nursing homes or other assisted care facilities. Also, research has shown a correlation between unintentional weight loss and three categories of potential cause: cancer, depression, and gastrointestinal disorders. Below are examples of these categories and other common causes:  

  • Cancer: Because cancer cells use more of the body’s energy than healthy cells, some cancer patients may burn more calories than they normally do. Along with other symptoms and a possible loss of appetite, these patients are likely to experience weight loss. This effect seems to be more pronounced in lung cancer and pancreatic cancer or other cancers related to the gastrointestinal system.   
  • Mental health: Mental health disorders like depression can include both weight gain and weight loss as symptoms. Depression-related changes to the hypothalamus and pituitary gland are known to increase production of hormones like cortisol that regulate metabolism, blood pressure, and other functions.
  • Anorexia: Anorexia and other eating disorders are associated with a loss of appetite and subsequent weight loss. There is also some evidence that other causes of unintended weight loss can trigger anorexia.  
  • Gastrointestinal disorders: Some of the diseases that affect the digestive tract include involuntary weight loss as a symptom usually either because of reduced appetite or malabsorption. When the body doesn’t absorb enough of the calories from ingested food, malnutrition and weight loss will result. This symptom is also somewhat common in celiac disease as well as Crohn’s disease and ulcerative colitis, the two main types of inflammatory bowel disease (IBD).  
  • Muscle loss: The loss of muscle mass, usually through aging or a severe lack of physical activity, is another possible cause of overall weight loss. Since muscle weighs more than fat, the loss can have a significant effect on body weight. The loss of muscle mass is also unfortunately associated with numerous other negative health outcomes.  
  • Hyperthyroidism: Hyperthyroidism is a condition where an overactive thyroid gland produces too much of the thyroid hormone. Among other things, thyroid hormone regulates metabolism; too much of the hormone can cause you to burn calories more quickly and force the body to switch to fat deposits and muscle for energy. 
  • Arthritis: Rheumatoid arthritis is an autoimmune disease that affects the joints; an abnormal immune response inflames joints and causes symptoms like pain, swelling, and stiffness. In patients who have arthritis, chronic inflammation can then lead to increased metabolism and weight loss. 
  • Diabetes: While type 2 diabetes is typically associated with weight gain, it can also include unexplained weight loss. In these cases, insulin in the blood isn’t used effectively and therefore isn’t helping cells receive glucose; because of this, the body turns to fat and muscle for energy. At the same time, though, blood sugar levels are high and can eventually inhibit kidney function.  
  • Heart and lung disorders: Certain disorders that affect the heart and lungs can cause relatively rapid weight loss due to a sudden excessive use of calories. In chronic obstructive pulmonary disease (COPD), the lungs slowly degrade and result in a long term difficulty breathing that requires more energy. In cardiac cachexia, a condition that often follows congestive heart failure, the weight loss comes from the muscle tissue in the heart.  
  • Addison’s disease: This rare autoimmune disease affects the adrenal glands and causes an insufficiency in cortisol production, a hormone involved in metabolism. These metabolic changes can cause a loss of appetite and otherwise unexplainable weight loss.  
  • Dysphagia: Dysphagia, otherwise known as difficulty swallowing, can often lead to weight loss. Regardless of the underlying cause of dysphagia, having a regular problem with the ability to swallow can cause a person to overall eat fewer calories and eventually lose body weight. Dental problems can also contribute to this effect.  

When to See a Doctor     

Unintentional weight loss may seem like an unambiguously good thing to most people, but more often than not it points to a health concern (especially for older people) that shouldn’t be ignored. And while it’s natural for a person’s body mass to fluctuate over time, significant unintentional changes are a red flag. Doctors recommend that you seek medical care if you lose 5% of your total body weight over a 6-12 month period without having made substantive changes to your diet and physical activity levels. Depending on your medical history and other symptoms, the doctor may use blood tests, hormone panels, or imaging tests to clarify the underlying cause.  

Weight Loss Solutions 

Losing weight without intending to is a real concern for some, but for many others the opposite is true. Over 40% of Americans are obese, and that brings a series of associated medical conditions. The multibillion dollar diet and exercise industries promise life-changing results when you buy their products, but few people actually find sustainable, long-term weight loss. Incorporating radical new changes into your life is hard to do, and so most people end up losing some weight and then gaining it all back within months or years. 

If you, like other Americans, have tried traditional weight loss methods without success, it might be time to consider a new path. At True You Weight Loss, we are dedicated to helping clients take a new approach to their weight loss journey. Non-surgical procedures like ESG help you permanently change eating habits that will lead to a fat-burning calorie deficit that is sustainable over the long term. If you’d like to learn more about ESG or any of our other offerings, please contact us today to request a consultation.

Dr. Christopher McGowan
Dr. Christopher McGowan

Dr. Christopher McGowan, MD, a leader in endobariatrics, specializes in non-surgical obesity treatments and is triple-board-certified in Internal Medicine, Gastroenterology, and Obesity Medicine. Renowned for pioneering endoscopic sleeve gastroplasty (ESG) with over 2,000 procedures, his global influence and research contributions define him as a top expert.

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