The idea that body fat is good for you is so unfashionable these days that it is hard to believe it could be true. As a result precious little research has been done to establish the facts. Until now, that is. The Open University believes zoologist Caroline Pond's pioneering work in the field is changing the way her scientific colleagues think.
Her breakthrough discovery is that adipose tissue, or fat, is not a random and unimportant element of mammal bodies but an essential biological component strategically placed to carry out a variety of important regulatory functions.
The specialised roles of fatty deposits are related to their location, whether in muscle areas, around the heart or surrounding lymph nodes.
Because this field is so unfashionable Dr Pond has had difficulty attracting grants for her work. Most research into adipose tissue is backed by pharmaceutical firms whose main interest is the development of slimming drugs.
Limited resources meant that back in 1982 when the project began Dr Pond's research subjects were the victims of local road accidents. Animal victims, that is. "I went out on my bicycle at night to pick up all sorts of dead mammals like badgers, hedgehogs, foxes and deer," she said. As her interest became known policemen, bus drivers and game keepers contributed to the supplies.
Dissecting her subjects, Dr Pond concluded that adipose tissue is far from being the surplus fat of popular conception but is in fact highly organised and forms a consistent pattern around mammalian bodies, just like nerves, blood vessels and bones.
"In fish, reptiles and most amphibians all the fat is arranged in one or two places close to the centre of gravity," she pointed out. "That is a sensible arrangement if the function of the tissue is simply as a storage facility which can enlarge and contract as the food supply dictates.
"But in mammals you never find that arrangement." Instead their fat is partitioned into many depots, some large and some very small, located in many different part of the body. "Even in very lean and healthy animals there are adipose tissue deposits on the heart, around the lymph nodes and between muscles," said Dr Pond. During the course of her work Dr Pond came to believe that some fat deposits have a role other than energy storage. This relates to regulating the immune system by, for example, providing white blood cells with the polyunsaturated fats they need to proliferate and protect against disease.
To extend her research Dr Pond has focused on "professional fatties", animals such as polar bears and arctic foxes for which fat is a way of life. Her subjects are usually shot by licensed hunters for food and she has to work quickly - not only is there much work still to be done but in just a few hours the carcasses freeze.