With all the negative reports about having excess weight or being obese, one might think weight loss is inherently good. Well, it can be deliberate such as from exercising or dieting for various personal and health reasons.

However, when weight loss is unintended and rapid, it can signal an alarming underlying health condition. In this post, we will discuss rapid weight loss, and its causes.

Read on to understand more about unintended rapid weight loss.

What is considered rapid weight loss?

According to health professionals, losing 0.45-0.9kgs (1-2pounds) a week is a safe and healthy weight loss rate. However, anything past that is considered rapid and could subject you to several health complications like nutritional deficiencies, gallstones, muscle loss, and a drop in metabolic processes.

Among the most common ways of losing weight fast is through vigorous exercise and following a low-calorie diet or a “crash diet” of below 800 calories per day.

People seem to be inclined to follow a low-calorie diet instead of exercising because it is easier to lose weight through diet than vigorous body exercise.

For beginners on weight loss either through exercise or diet, losing more than 2 pounds in your first week is perfectly normal. The weight loss during this period is called “water weight.”

This is because when you take fewer calories than your body burns, they get stored as energy in the form of glycogen. The glycogen in the body is water-bound; therefore, when you burn it for energy, the body releases it as water. Because of this, you might experience a rapid weight loss in your first week of training. Once the glycogen is used up, your weight loss should remain stable at 1-2pounds per week.

Unexplained and unintended rapid weight loss can be caused by various underlying reasons. Here are some of the possible causes.

1. Gut disease

Bowel diseases are usually characterized by nausea or vomiting, decreased appetite, change in bowel habits, and abdominal pains, which can creepily lead to weight loss.

Some of the common examples of gut problems include inflammatory bowel diseases (ulcerative colitis and Crohn’s disease), chronic liver and celiac diseases. You may be referred to a gastroenterologist for diagnosis, which always requires endoscopy or imaging studies.

2. Presence of intestinal parasites

It may sound creepy, but it happens from time to time. And, among the most common internal parasites in the United States are Cryptosporidium and giardia parasites.

Generally, weight loss is due to malnutrition and malabsorption because these internal parasites take in nutrients that should be absorbed by the body to build muscles and strengthen bones.

Personal hygiene like washing hands regularly is recommended to avoid parasites from attacking you. Also, during travel, ensure you take clean water for drinking and make sure the foods are handled correctly at the hotel.

Treatment will vary depending on the type of parasite detected, which will most likely require some lab tests.

3. Depression

Depression and other psychological conditions such as anxiety and stress can result in rapid weight loss. Depression can lead to decreased appetite and a decreased caloric due to eating disorder which is often associated with weight reduction.

Treatment of depression often involves a multidisciplinary approach: medication, lifestyle and dietary education, counseling, and behavior modifications.

4. Hyperthyroidism

This is the production of too much thyroxine hormone, which can be due to overactive thyroid. Usually, weight loss is due to increased metabolic rate and increased gut mobility resulting in malabsorption.

Also, you can experience sleep changes, fatigue, irritability, and difficulty controlling your body temperature.

There are several treatment approaches to this condition once it is diagnosed that an individual can discuss with their primary care provider or an endocrinology specialist. The approaches may include radioactive iodine, surgery, and medications.

5. Diabetes

When you have diabetes and have insufficient insulin, your body may not get enough glucose for energy from the blood cells. This may force the body to break down fats and muscles for the required energy resulting in weight loss.

Other common symptoms of diabetes include sweating, excessive urination and thirst, numbness, and fatigue. Your family doctor should test you to determine if you have diabetes, especially if you come from a family with a history of diabetes.


Rapid, unexplained weight loss can be attributed to many causes, medical and non-medical. Usually, a combination of factors can result in general weight loss and health decline.

Rapid weight loss may be due to diabetes, intestinal parasites, depression, hyperthyroidism, or gut diseases. Take note, these might only be common causes, and there might be others not outlined here. Make a date with your primary care provider so you can get clear insights and get tested for any underlying condition that might result in rapid weight loss.