Two pet mice, one fat and one thin

Skinny genes

What part do our genes play in body size?

Genes and environment work together to influence your body size and shape, and a few genetic variants can make a big difference. Leptin, an appetite-regulating hormone that reduces hunger, is normally produced by cells that are storing fat; genetic mutations that block production of the hormone or its receptor can lead to an unremitting drive to eat. In addition, obesity seems to go with a loss of sensitivity to leptin.

A newly identified gene known as FTO can also induce obesity in mice when its activity is increased by giving the mice extra copies of the gene. Evidence from human data also indicates that variations in the gene are linked to becoming overweight, although it is not yet known exactly what the gene does.

Lead image:

crwr/Flickr CC BY NC ND


About this resource

This resource was first published in ‘Food and Diet’ in June 2011 and reviewed and updated in August 2016.

Genetics and genomics, Physiology
Food and Diet
Education levels:
16–19, Continuing professional development