Why women pile on the pounds as they age - and it may not be their fault

It's one of the most frustrating things about getting older - piling on the pounds, no matter how hard you try to keep them off. Now scientists have discovered one reason - for women, at least. 

 After the menopause, the activity of a particular enzyme involved in fat production increases. Known as Aldh1a1, it causes us to store a dangerous type of fat around the internal organs, known as visceral fat. 

This is strongly linked with type 2 diabetes, heart disease and cancer and is produced by an enzyme triggered more in females when both sexes eat a high fat diet. Researchers at the University of Ohio found that the female hormone oestrogen suppresses the effects of the enzyme. 

The downside is that once levels fall after the menopause, it is free to work its magic - hence the weight gain. By targeting Aldh1a1, researchers may be able to develop an obesity treatment specifically for women, said study researcher Ouliana Ziouzenkova, an assistant professor of human nutrition at Ohio State University. 

The researchers surgically removed the ovaries of mice to test whether oestrogen could be related to visceral fat production in females. As soon as the animals became menopausal and weren't producing estrogen, they began to produce retinoic acid, which led to visceral fat formation.