Unexplained Weight Loss: Causes & Treatments

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While many people are trying to lose weight, there is something particularly worrying about unexplained weight loss, as it is typically indicative of an underlying medical condition that requires attention. Losing a pound here and there may be the result of fluctuations in your diet, exercise regularity, work schedule, sleep, stress levels, medications and substance abuse, among others. However, unexplained weight loss is typically defined as the loss of more than 5% of your body weight in less than six months. That represents a significant loss, especially if you aren’t trying to lose that weight.

If your body rapidly loses weight, the symptoms can often be serious, including muscle weakness and fatigue, depression, a slower metabolism, a loss of appetite, an increase in illnesses (weakened immune system) and a change in your frequency of going to the bathroom. Depending on the root cause of your unexplained weight loss, your symptoms may differ significantly, possibly including shortness of breath, cognitive confusion, stiff muscles, low blood pressure, blood in the stool, abdominal cramps, vomiting, coughing, irregular heartbeat, slow healing of bruises and cuts, numbness and anxiety. Unexplained weight loss often affects older people or those who have had issues with malnutrition in the past, but as the causes below illustrate, this condition can affect anyone.

Causes of Unexplained Weight Loss

Some of the more worrying causes of unexplained weight loss include diabetes, peptic ulcers, celiac disease, cancer, depression, HIV/AIDS, stomach ulcers, ulcerative colitis, hypo/hyperthyroidism, COPD, Addison’s disease and rheumatoid arthritis. This is not an exhaustive list but these are some of the most common causes of inexplicable weight loss.


When you first develop diabetes, often before you realize you are suffering from the condition, your body is expelling glucose that it can’t use, which results in frequent urination. Furthermore, to compensate for the lack of nutrients it is absorbing, the body will start to leech nutrients from muscles, which causes a loss in overall weight.

Celiac Disease

This inability of the body to absorb or process gluten also causes inflammation in the gut, which makes nutrient uptake far less efficient. This if often accompanied by diarrhea and stomach upset, which can kill your appetite and result in less calorie intake every day. Fortunately, going gluten-free is easier now than ever before, given the broader awareness of Celiac disease in the population.

Thyroid Issues

If you suffer from hyperthyroidism, it often means that your body’s metabolism is working too quickly, burning more energy and resources than it actually needs, which makes it difficult to keep up with the calories being demanded by the body.

Eating Disorders

Even if you don’t self-identify having an eating disorder, anorexia is quite common in people who are stressed, overworked or dealing with self-image problems. Consistently cutting back on the quantity of food you eat, without altering any other aspects of your physical fitness or behavioral patterns, can cause rapid weight loss.


When anxiety and depression strike, your appetite is often affected by the flood of stress hormones in the body, making the idea of eating food very unpleasant. When your body begins losing weight, many people suffering from chronic depression don’t even realize it until the weight loss has reached dangerous levels of malnutrition.


The growth of tumors in the gastrointestinal or digestive system can cause inflammation that prevents nutrient absorption, causing food to simply pass through your body, without all the calories being taken in by the body. The general weakness and discomfort of cancerous symptoms can also make eating unpleasant, even negatively affecting the taste of food.

Stomach Problems

Various conditions affecting the stomach, such as ulcerative colitis, stomach ulcers, stomach cancer, peptic ulcers, or parasitic infections (e.g., hookworms) can cause severe inflammation in the stomach, preventing the proper absorption of nutrients from the food we eat, which will eventually lead to weight loss.


If you suffer from COPD, you may burn up to 10 times as many calories while breathing as a normal person, meaning that your body will often burn more calories than you are taking in a given day, leading to rapid weight loss.

Rheumatoid Arthritis

This autoimmune disease attacks the body’s own tissues, but this isn’t limited to the joints and ligaments. It can also affect tissues in the gut, which are responsible for digestion, making nutrient uptake more difficult, leading to unexplained weight loss.

Addison’s Disease

This condition affects the adrenal glands, which are crucial to many different bodily processes including the production of cortisol, adrenaline and aldosterone. These are some of the most important hormones in the body, and without their regular presence in the body, it will cause fatigue, loss of appetite and rapid weight loss.


If you are suffering from this condition, the medication you may be prescribed can kill your appetite, or even make it more difficult for your body to absorb nutrients.

Treatments for Unexplained Weight Loss

Given the long list of potential causes of unexplained weight loss, addressing those more serious issues is the best way to treat this type of weight loss – or at least prevent it from continuing. Once the underlying condition is treated or mitigated, you can gain the weight back by speaking with a nutritionist about a healthy high-calorie diet that can get your body back to normal. Some of the classic weight-gain techniques include the following:

Eat More Meals

Perhaps the most obvious solution to the problem of weight loss is to simple eat more meals. Ensure that they are high in calories and “good” fats, which can boost your body weight without putting your heart health and overall wellness in jeopardy.

Less Water Intake

When attempting to lose weight, many people drink 1-2 glasses of water to help fill their stomach and suppress their appetite. Therefore, when trying to gain weight, avoid drinking water before or during meals, as it will increase your appetite and allow you to consume more calories before feeling full.

Bigger Plates

A psychological approach to gaining weight is to use larger plates, just as a psychological approach to losing weight is to use smaller plates. This will encourage larger portions and more calorie intake per meal, helping to bulk you up and prevent malnutrition.

Protein Shakes

Protein is an essential part of muscle building and as many regular exercisers know, muscle weighs more than fat. By adding a protein shake between meals, you can ensure that your body has the raw materials to increase muscle production and boost your overall mass.

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