What You Need To Know About Unexplained Weight Loss

What is unexplained weight loss?

Unexplained weight loss happens when you lose a significant amount of weight even when you’re not trying to. It's important not to ignore it as it may be a sign of something more serious, like a life-threatening illness, especially in people over the age of 65.

How much weight loss is alarming?

Our weight fluctuates from day to day for a variety of reasons, including hormones, diagnosed or undiagnosed illnesses, food consumption, and exercise, among others. In fact, it’s totally normal for weight to fluctuate as much as five pounds in a single day.

However, if you lose ten pounds or around 5% of your body weight (multiply your current weight times 0.05 to determine what 5% of your body weight is) in a period of six to 12 months, it can be a cause for concern, especially if you haven’t made any serious lifestyle changes. In people over 65, even a smaller amount of weight loss may necessitate a trip to the doctor.

If you notice unexplained weight loss, consult your doctor to ensure that there are no underlying medical conditions that are making you lose weight. This is especially important if you’re also experiencing other symptoms.

When is weight loss actually unexplained weight loss?

If you lose weight over a period of six to 12 months, think about what you’ve done over this period. It’s important to carefully examine your lifestyle to see if your weight loss is truly unexplained.

For example, if you had taken any actions to lose weight, started exercising more, had a serious illness or surgery, or started a new diet, these may explain why you lost so much weight.

However, if you didn’t do any of these things, the weight loss may be considered unexplained.

How common is unexplained weight loss?

Unexplained weight loss isn’t particularly common, though it is more common in older adults, especially those over the age of 65. Still, it affects thousands of people every year and should not be ignored.


Unexplained weight loss is usually a symptom of something more serious. It’s difficult sometimes to notice it, especially if you don’t pay much attention to your weight.

The biggest symptom of unexplained weight loss is a loss of more than 5% of your body weight in six to 12 months. However, you may also feel faint or lightheaded due to weight loss, or notice changes in your appetite.

When you consult a doctor, they may ask how much weight you had lost and when it started, so keep track of this information when possible.

Diagnosing unexplained weight loss

Your doctor will probably ask you a few questions about when you first noticed losing weight and any other symptoms you may be experiencing that may or may not be related to your weight loss. They may ask about recent illnesses, dental problems, medical history, and your eating and exercising habits.

They may also attempt to rule out other diagnoses with blood tests and imaging scans, if necessary. The goal is to find out why you’re losing weight. If they determine that your weight loss is normal and healthy, you’ll likely need to take no further action.

However, if your weight loss is unexplained or due to a serious illness, your doctor may recommend further treatment.

When should you see a doctor?

If you are concerned about any weight you’ve lost in the past few months, your doctor can tell you if this weight loss is normal or a cause for concern. If you have any other symptoms related to this weight loss, see a doctor as soon as possible.

Your primary care provider should be able to get you pointed in the right direction so you can find specialists to help diagnose any underlying illnesses.


Many things can cause unexplained weight loss. Some of them are more serious than others. In all cases, however, you should see your doctor to figure out the source of the weight loss.

If you or someone you love has lost more than ten pounds in the previous months, figuring out the cause of this weight loss is the first step toward maintaining a healthier weight.

Here are a few of the most common causes of unexplained weight loss:


Cancer causes inflammation, which can affect your metabolism. A growing tumor may also increase your body’s energy expenditure, burning more calories than you’re eating.

Obviously, if cancer is causing your unexplained weight loss, it’s really a must to catch it early for a better prognosis.

Thyroid problems

Your thyroid helps control your metabolism. If you have an overactive or underactive thyroid gland, you can have rapid and serious changes in weight.

Crohn’s disease

Crohn’s disease is an inflammatory bowel disease that makes it difficult for your body to absorb nutrition from the food you eat, which can cause weight loss.


Diabetes causes your body to have trouble getting glucose from your blood to your cells. Instead, your body may burn fat and muscle to attempt to provide you with the energy you need.

Dental or swallowing problems

If it hurts to eat or if you are unable to properly swallow, you will most likely lose weight at an alarming rate. Don’t ignore this, as this can worsen your health in the long run.

Depression, anxiety, and other mental disorders

Mental illness can seriously affect your appetite. When you are depressed or anxious, you may have no energy or desire to eat regular healthy meals. In fact, you may not care at all whether you eat or not, which can seriously affect your health.

Many people also suffer from eating disorders, like anorexia or bulimia, and may lose weight rapidly.

Other possible causes

Other possible causes of your unexplained weight loss include medication side effects, parasites, and drug abuse. If you are taking medications for a certain condition, and you notice yourself losing weight, talk to your doctor immediately so they can assess your health and replace your medication if necessary.

Although uncommon, a parasite like a tapeworm can cause unexplained weight loss. Certain drugs may also decrease appetite to the point where a person hardly eats, leading to weight loss.

This is not a complete list of health issues that cause unexplained weight loss. If you’ve lost a significant amount of weight in a short period of time, there are dozens of other things that may be the root of the problem.

Keep reading to learn more about the potential causes of unexplained weight loss.

What are the risk factors for developing unexplained weight loss?

Most people who develop unexplained weight loss are over the age of 65. Age and genetic predisposition to certain diseases are the biggest risk factors for developing them.


If you have unexplained weight loss, you have two biggest concerns: what’s causing it and how to treat it. So, your first step toward recovery is to see a doctor for assessment and get any other conditions diagnosed. You can then work to get your weight back on track.

How is unexplained weight loss generally treated?

The treatment for unexplained weight loss usually involves pinpointing the cause (if any) and treating the root of the problem. Your doctor will ask you questions about your weight loss and about other things going on in your life. They may ask about changes in your mood, appetite, bathroom habits, and if you’ve been feeling unwell or tired.

You’ll receive treatment based on any conditions that are identified. If no condition is determined to have caused the weight loss, your doctor may simply want to monitor your weight closely to see if you lose any more.

To gain the weight back, your doctor may recommend that you drink high-calorie nutrition shakes or just eat more calories in general.

Doctors & specialists

If you’re concerned that you’ve lost weight, make an appointment with your primary care provider. While there are specialists who may be able to help with your unexplained weight loss, it’s still best to start with a doctor who knows you and your medical history, so it’s easier to rule out things that may be causing your weight loss.

Your general practitioner should be able to diagnose the problem, but the treatment depends on the cause. Your GP may refer you to a specialist to get the right treatment for the illness or condition that is causing your unexplained weight loss.

Gastroenterologists, for example, can help to diagnose and treat problems in the stomach and intestines, while psychiatrists can treat issues like depression and anxiety.

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