Expert Q&A

Unintentional rapid weight loss: What causes it?

I used to be averagely built. But lately, I’ve started losing a lot of weight. I don’t feel sick. Why is this happening to me? -Raul from Tennessee

Unexplainable weight loss can be a symptom of a number of diseases or conditions. The causes may be due to:

1.   Weight loss due to gastrointestinal or digestive diseases and disorders

If you have a condition such as irritable bowel syndrome, celiac disease, Crohn’s disease or colitis, you may have persistent diarrhea or other GI complications. These are likely symptoms of malabsorption and may lead to weight loss. A gastroenterologist can confirm or rule out the presence of these diseases.

2.   Hyperthyroidism causing weight loss

When the thyroid gland overproduces certain hormones, unexplained weight loss may occur. Your doctor can order a simple panel of tests to determine if an overactive thyroid is the cause of your weight loss.

3.   Medication and a resulting weight loss

Certain types of medication, including some antidepressants, have been known to cause unexpected weight loss. Read the accompanying packaging on your prescription medications and talk to your pharmacist or doctor if you suspect this might be the cause of your weight loss.

4.   Weight loss as a result of cancer or diabetes

In some cases, undiagnosed diabetes is often preceded by unexplainable weight loss. With certain types of cancer, both the disease and the treatments may contribute to weight loss. With either diabetes or cancer, you might not “feel sick,” but losing weight could be an indication that you are sick.

5.   Losing weight due to old age

As you age, you may find you eat less due to physical constraints or difficulties with chewing and swallowing.


What should you do if you are losing weight unintentionally?

Losing more than 10% of your weight over a period of six months is cause for concern. If this happens, you should talk to your doctor, regardless of how old you are.

Katie Clark, MPH, RD
Contributing Expert

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