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The Danger Behind Unexplained Weight Loss: Most Common Causes

Published on: May 10, 2019

The Danger Behind Unexplained Weight Loss: Most Common Causes

People who follow a ketogenic diet and exercise expect themselves to lose weight safely. But what about losing weight even without trying? Unexplained weight loss can happen to anyone for various reasons. If you’re experiencing this or know someone who does, read this guide to learn more.

What Is Unexplained Weight Loss?

Unexplained weight loss happens when a person unexpectedly loses at least 5% of his body weight in 6-12 months. If you weigh 120 pounds and lost 10 pounds in 6 months without doing anything, you might have a good reason to worry.

Based on a study conducted on 2,677 patients, unintentional weight loss can be caused by a cancerous disease, non-cancerous disease, or psychiatric disorder. Social factors are sometimes a reason as well. Regardless of the cause, it is important that you seek medical evaluation [1].

Who Is at Risk for Unexplained Weight Loss?

Anyone, male or female, is at risk for involuntary weight loss. However, this phenomenon usually occurs even more so among older adults. Here’s some information that we gathered concerning the following age groups:


Children and teenagers

Overweight adolescents often practice weight control. This makes sense considering that western societies value so much being thin.

Children, on the other hand, are typically motivated to lose weight to either get better at sports or to avoid being teased by their peers [2]. You should always be concerned if a child loses weight though, unless the weight loss was supervised by a doctor [3].


The same study also showed that males who lost weight were often older, actively smoked, or had malignancies. Physical examination and various tests had usually revealed abnormalities [1].


This study also revealed that females with unexplained weight loss often had a psychosocial disorder and were lower in socioeconomic status. The amount of weight lost was lower than males [1].

Adults 65 years or older

As previously mentioned, involuntary weight loss is common in elderly individuals. It’s a risk factor that loved ones and caregivers should certainly pay attention to. Many older adults will not complain that they’ve lost weight. Another thing to note is that involuntary weight loss is linked to increased mortality and progressive disability [4].

Signs & Symptoms That May Be Associated with Unexpected Weight Loss

Since unexplained weight loss can be linked to a health condition, you may want to pay attention to other signs and symptoms such as:

1. A loss of appetite

Decreased appetite means that a person has less desire to eat. Bacterial or viral infections lead to a temporary loss of appetite. If poor appetite persists, it can imply that the person has a serious underlying condition [5].

2. Frequent infections

A weakened immune system makes a person prone to acquiring infections. Do you often have cough and colds that last long and are hard to treat?

3. Fatigue

At some point in our lives, we experience fatigue - such as when we remain sedentary or miss sleep. However, people who feel fatigue due to a medical condition often describe the fatigue as “persistent.” Furthermore, fatigue can prevent them from functioning normally [6].


4. Change in bowel habits

Some people who lose weight suddenly will notice a difference in their stool frequency, color, and shape. Abdominal pain and an alternating case of diarrhea and constipation can also occur.

According to the Cleveland Clinic, there is no universal definition of a normal bowel movement, as everyone differs in bowel habits. In general, we defecate from 0 to 4 times a day. Be sure to note any unusual change in your bowel movements.

Common Causes

Before we dive into serious health issues that can lead to an unexplained weight loss of at least 5%, let’s explore two common weight loss triggers:


1. Side effects of medications

Some prescription medications disrupt the normal flora of the gut and trigger side effects like nausea and diarrhea. These symptoms can make a person lose weight because he or she loses water, electrolytes, and ultimately the appetite to eat. If you’re currently taking a medication, check the label for any side effects or consult your doctor about this.

2. The aging process

Not all older adults lose weight unintentionally because of an underlying illness. Weight loss in persons over 70 can result from the normal aging. A decrease in an elderly person’s ability to move affects their food shopping and also affect their cooking. Further, older people often have a naturally reduced sense of taste and smell.

10 Serious Medical Conditions Behind Unexplained Weight Loss

Here we discuss 10 serious health conditions that will help explain why you or someone you know may have dropped pounds unexpectedly.

1. Hyperthyroidism

Hyperthyroidism or an overactive thyroid can cause unexpected weight loss. What happens in this case is that the thyroid gland (located in your throat) produces excessive thyroid hormone.

Thyroid hormones regulate your metabolism. So if you have increased thyroid hormone levels, your body expends more energy even when at rest. This can significantly reduce your weight despite a good appetite [8].

In addition to a drastic weight change, your doctor will look for other signs and symptoms such as increased bowel movements, sleep disturbances, intolerance to heat, and fatigue.

2. Diabetes

When we think of diabetes, we often associate it with weight gain. The truth is that diabetes also causes weight loss.

Type 1 diabetes or “insulin-dependent diabetes” happens when your pancreas produces little to no insulin. Without insulin, sugar cannot enter your cells, and so that sugar remains in the bloodstream.

When type 1 diabetes remains untreated, sugar (in the form of glucose) builds up in the blood. Your body tries to compensate at that point by letting your kidneys excrete glucose in your urine.

Losing all that unused sugar means losing calories too, and that can enable weight loss. Unexpected weight loss happens often in types 1 and 2 diabetes, although it’s most common in type 1.

In Jimmy Moore’s The Livin' La Vida Low-Carb Show, Dr. Tom Jelinek revealed that he was diagnosed with type 2 diabetes and how he was able to reverse it with the ketogenic diet [9].

3. Congestive heart failure (CHF)

Congestive heart failure is another disease that leads to progressive unintentional weight loss. In CHF, the heart cannot pump blood at a high enough level throughout your body.

Since your intestines need an abundant supply of blood to properly digest and absorb nutrients, reduced blood supply may well explain an occurrence of weight loss.

Some health issues that can weaken your heart include high blood pressure, coronary artery disease, diabetes, and thyroid disorders.

On that note, please be aware that one of the misconceptions of the keto diet is that it increases the risk of heart disease. The truth is that the keto diet actually reduces cardiovascular risk, including conditions of diabetes and obesity.

4. Chronic obstructive pulmonary disease (COPD)

Based on one study, about a third or more of disabled individuals with COPD will lose weight [10]. This particular lung disease often makes it difficult for a person to breathe normally with airflow in the lungs becoming obstructed.

Common conditions that lead to COPD are emphysema and chronic bronchitis.

COPD patients typically exert more effort when breathing. This increase in effort burns 10 times more calories than in a person with healthy lungs. Therefore, COPD patients need to follow a plan regarding their individual calorie consumption per day, and with the direct help of a dietician.

5. Cancer

Cancer is a disease where cells grow in an uncontrolled manner. How cancer is classified depends on the origin and location of the cancer. Regardless, cancer leads to weight loss which often begins with that person losing appetite.

Why does a cancer patient often waste away? The answer here is that your immune system produces cytokines (proteins that mediate inflammation) to defend your body against cancer. Cytokines lead significantly to decreased appetite and weight loss [11].


6. Depression

It is normal for a person to feel sad due to perhaps the loss of a job, loss of a loved one, or from some other very stressful experience.

However, if sadness in any individual remains for 2 weeks or longer, and that person loses interests in daily activities, sleeps little or too much, cannot concentrate, or thinks of suicide, that person is clinically depressed.

Loss of appetite is common in depressed individuals because they often lose the energy and interest to eat. However, it is important to note that some people tend to overeat instead during a major depressive episode which of course can then lead to weight gain [12].

7. Alzheimer's Disease

Weight loss happens in many patients with Alzheimer’s Disease. As the disease progresses, a person loses their appetite and often forgets to then cook and eat.

Researchers also found out that Alzheimer’s patients can eventually lose their sense of smell, explaining why they could certainly find food less appealing [13].

When it comes to proper dietary planning for Alzheimer’s Disease patients, a growing number of studies show that a low-carbohydrate, high-fat ketogenic diet often helps reduce brain damage. Further, ketone bodies produced in ketosis will typically provide more energy than glucose [14].

8. Eating disorders

“Eating disorders” refer to disturbances in a person’s eating behaviors that are influenced by his or her thought processes and emotions. Many people assume that eating disorders are a lifestyle choice. They are not. In fact, they are considered to be a serious illness [15].

One who has an eating disorder often preoccupies himself or herself with thoughts of food and body weight. One of the factors that trigger an eating disorder is the culture in which we live. It is one that is obsessed with a perfect body.

Anorexia nervosa is an eating disorder that results in severe weight loss and life-threatening complications. Not only can anorexia patients literally starve themselves, but they often exercise excessively.

9. Rheumatoid arthritis

If you or a loved one has painful joints in both hands, feet, elbows, knees, and ankles despite being young, there is a good reason to suspect possible rheumatoid arthritis.

Rheumatoid arthritis is the second most common arthritis in the United States, being a serious condition that affects 3 million people [16].

According to Vanda Sheth, RD, CDE, cytokine production in people with rheumatoid arthritis will increase their resting metabolic rate and protein breakdown. This in turn leads to weight loss [17].

10. Human immunodeficiency virus disease (HIV)

Serious weight loss happens during the third stage of HIV. In this later stage, a person’s immune system is badly damaged.

There are several reasons why someone with HIV loses weight. For example, mouth sores can make it very painful for an HIV patient to eat. That person may also be depressed at the same time, allowing him/her to lose interest in food.

When Should You See a Doctor?

If your weight loss is upsetting you because you know that you eat well, and that you don’t follow any weight loss plan or take any medication, do make an appointment with your doctor right away. Even if you have a long list of reasons why you have lost at least 5% of your weight during the course of 6 to 12 months, it is still a good idea to get yourself checked out by your doctor.

Strategies That Help Avoid Unexpected Weight Loss

Losing weight quickly does have negative consequences. If your body lacks certain nutrients, you could be susceptible to infections. Nutritional deficiency could lead to anemia, weaker bones, poor vision, and more.

Strategy choices to prevent unintentional weight loss should be dictated by the underlying disease involved. If you want some general tips on this, here are five of them:


1. Weigh yourself regularly.

Purchase a scale. Weigh yourself once a week or every other week. That’s the simple and accurate way to keep track of how much weight you’re losing or gaining. Do it at the same time and day each week. Wear roughly the same clothing each time. It’s best to weigh yourself in the morning, after emptying your bladder and before eating your breakfast.

Also, bear in mind that your weight fluctuates typically throughout the day. You might also want to consider other ways of assessing your weight loss or gain. For example, measuring the size of your arms and waist.

2. Take a multivitamin or mineral supplement.

People with specific medical conditions that lead to deficiencies can benefit from a multivitamin or mineral supplement [18]. For example, patients with anorexia may be quite deficient in vitamin A, vitamin E, and selenium [19].

Taking supplements will also boost your energy, boost your immune function, and support a healthy weight. However, if you’re taking any medication, please be aware that vitamin and mineral supplements may interact with certain prescription and over-the-counter medications.

3. Add healthy calories in your diet.

A basic rule for gaining weight has always been to consume more calories than you burn. To do it the right way though, be sure to choose natural foods loaded with nutrients. Some examples are eggs, red meat, poultry, seafood, nuts, and seeds.

4. Make mealtime a pleasant experience.

One of the ways to help someone with a decreased appetite is to help provide them with an enjoyable mealtime experience. This applies especially to those with Alzheimer’s Disease.

Keep distractions to a minimum so that each individual can focus on eating. Don’t offer too many food options or it can get overwhelming for them. Eat meals together so that this person can look forward to this as a social event.

5. Keep a food diary.

Maintain a record of what you eat and drink as well as the amount. Whether it’s your morning cup of coffee or afternoon snack, be sure to write those down. Your food diary can be a simple notebook or an app that allows you to take down daily notes.


Aside from writing down your food intake, specify how you actually feel before and after eating or drinking something. Do you feel bloated? Sluggish? Anxious? Happy? Show your doctor your food diary on your next appointment. It will help your doctor identify food intolerances, along with those factors that affect your appetite and your food choices.


There are many reasons for unexplained weight loss. If you feel you have done nothing to achieve weight loss and have lost 5% of your normal body weight in a year, please get evaluated by a medical professional. You need to make sure that your health isn’t in jeopardy.


  • Anyone can lose weight unexpectedly. However, one study indicated that it is more common in older individuals.
  • Common reasons for unexplained weight loss include advanced age, medications, psychiatric, cancerous, and non-cancerous health conditions.
  • Signs and symptoms that may accompany unintentional weight loss will include appetite loss, frequent infections, fatigue, and a change in bowel habits.
  • To prevent weight loss, weigh yourself on the scale, consider taking supplements, eat healthy foods to increase your calorie consumption, keep meal times pleasant, and keep close track of what you eat and drink.


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  14. Broom GM, Shaw IC, Rucklidge JJ. The ketogenic diet as a potential treatment and prevention strategy for Alzheimer's disease. 2018 October 10 -
  15. National Institute of Mental Health. Eating Disorders: About More Than Food. 2018 -
  16. Cleveland Clinic. Rheumatoid Arthritis. 2017 November 16 -
  17. Sheth VR. Why does Rheumatoid Arthritis cause weight loss?
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  19. Achamrah N et al. Micronutrient Status in 153 Patients with Anorexia Nervosa. 2017 March 2 -

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