Men with prostate cancer may experience unintended and significant weight loss. There are five reasons why this can happen.

The first reason is rather obvious: anxiety and/or depression over the illness. Both anxiety and depression suppress appetite.

Another well-known explanation is the sick feeling that chemotherapy often causes. The drugs can also alter the patient’s perception of how foods taste.

But there are less obvious reasons why prostate cancer can cause a man to lose weight – even if he doesn’t have any pre-existing excess body fat.


Prostate cancer “increases the risk of urine infection — infection anywhere puts someone off their food,” says Dr. David Beatty, MD, a retired general practitioner with 30+ years of experience and an instructor of general medicine for 20 years.

Kidney Dysfunction

A tumor in the prostate can impede the urine stream. “By obstructing the flow of urine, renal failure is more likely to occur — with its associated anorexia [poor appetite], malaise and nausea,” explains Dr. Beatty. In short, feeling sick means less hunger.

Cancer Spread

Prostate cancer will spread if not treated early enough. One possible location of a metastasis is the liver.

“Metastases in the liver can further impede appetite by causing nausea, and feeling full after small amounts of food,” says Dr. Beatty.

In addition to loss of appetite leading to unintentional weight loss, prostate cancer can also cause pain. 

Where Can Prostate Cancer Cause Pain & How Does It Feel?

Dr. Beatty has worked in primary medicine, surgery, accident and emergency, OBGYN, pediatrics and chronic disease management. He is the Doctor of Medicine for Strong Home Gym.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer. 


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