1. Hormone imbalance, which can occur during puberty or after the age of 50, where the testosterone levels drop in most men's bodies.

2. Liver damage. If the liver is damaged, it would not be able to adequately metabolise the oestrogen hormone that is present in men's bodies, resulting in hormonal imbalance.

3. Certain drugs, including some antibiotics, anti-ulcer and cardiovascular medications, have sometimes been found to affect the balance of hormones in the body.

4. Klinefelters syndrome, which affects one in every 650 males and is the main genetic cause of gynaecomastia.

5. Obesity - people are eating more and getting fatter. Those fat deposits can end up in men's breasts.

This story was first published in The New Paper on Dec 26, 2008.