Most people have some idea of what a hormone does. We have lots of hormones that work together in complex ways to keep our bodies working. The overall hormone system is called the endocrine system and its study is called endocrinology.
Its quite a key area for understanding health so it isn’t surprising that there is a learned body devoted to it called, with admirable straight forwardness the Society of Endocrinology. Its a subject I have to confess I know much less about than I would like, and so I was both pleased and impressed to see that the Society of Endocrinology is promoting its science by holding an essay competition. The Biologist has just published the 2009 winner, which is both very readable and very intriguing. Its written by someone called Kylie Beale of Imperial College. I am afraid that is all I know about her, but she does write well.
She reveals some new aspects to the way the body manages fat. We all know that obesity is a major public health issue, and a lot of us have our own issues with our own fat levels. And if you ever have tried to lose weight, you will be very aware that the body seems to have plenty of tricks up its sleeve to keep you pear shaped.
Most of our fat is simply a store of energy. Its a store we never use up because we are continually being tempted by delicious food options. Pies are my personal weakness. Our endocrine system is set up to use and store energy efficiently and signals that we are hungry before it burns off the fat we already have.
But it turns out that there are some fat cells whose main purpose isn’t storage but temperature control. These cells are quite different in appearance and are called brown fat cells. The body is able to modify the numbers of these cells and where they are deployed in response to our life styles. Norwegian lumberjacks for instance have been found to have unusually well developed brown fat cells in their necks – this keeps the blood flowing to their heads warm while they are working out in the cold.
The distribution of brown fat cells can be monitored quite precisely using modern techniques and some intriguing patterns are beginning to emerge. Babies have very high levels of brown fat. This isn’t surprising given that they have to keep a small body with a large surface area warm.
It also seems that leaner people tend to have more brown fat cells. This is manifested in young women having much higher levels than middle aged men. As a middle aged man I can vouch for my body’s habit of depositing fat in aesthetically unpleasing places. I hadn’t fully appreciated that not only was there too much of it in the wrong place, it also isn’t the best type to have.
The ability of the body to alter the pattern of brown fat cells in response to the kind of life we are leading sheds light on some things we take for granted. For a start, it explains why we feel the cold as winter comes on but by mid-winter are taking it in our stride. We get used to the cold by enhancing our brown fat deposits. The heavy carbohydrate rich food we crave when the weather worsens is needed to feed these mini radiators. The light meals and salads we are happy with in summer just don’t have a high enough energy value.
It also offers another angle on possible solutions to the obesity problem. Drugs might be developed that trigger off brown fat formation for example. A more intriguing possibility is using bursts of cold to stimulate its development. It might even be as simple as advising people to hold off on the central heating. I have a feeling we will be hearing more of brown fat cells.
Thanks to The Biologist for publishing the article this post is based on, to Kylie Beale for writing it and the Society of Endocrinology for sponsoring it. The striking picture of the portly gentleman is from Rosino on Flickr.