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“The answer sounds simple enough at first: when we have a lot of brown fat. The subject as a whole is pretty complex, however. For one thing, it is important to distinguish between white and brown fat. White fat is the kind of fat that overweight people have rather too much of. White fat stores energy. When we eat too much, we put on weight. There is another type of fat in the human body, however – brown fat. Unlike white fat, it does not store energy. On the contrary, brown fat burns energy – and can therefore help us lose weight. Incidentally, the fat cells are said to be brown because they contain a large number of mitochondria – the “powerhouses” of the cells – and are supplied with a lot of blood. Both mitochondria and blood are rich in iron, which is what gives the cells their brownish colour.
Brown fat can be essential for survival
We all know how we react when it is cold: we feel cold and our body shivers. The muscles of a new-born baby are not yet able to prevent the body from cooling down by shivering, however. This is why brown fat plays a very important role in newborns: it keeps the body warm. Brown fat is also essential for survival in mammals which hibernate: the brown fat protects them from hypothermia during this period of almost complete inactivity. It was long thought that only babies and certain mammals have brown fat, but radiology images proved a while ago that adult humans also have brown fat. The brown fat is not to be found everywhere in the body, but only in certain places: in the upper body, along the shoulder blades, in the deeper neck regions, on the large blood vessels and along the spine.
Many factors influence brown fat
You may now be asking yourself why we do not all have the same slim figure. Brown fat only produces heat and burns energy when we feel cold or when it is activated in some other way – for example when we do sport. The muscles then release signals that cause the brown fat cells to be activated. This is another reason why exercise is healthy. Older people have less brown fat than young people. The central nervous system plays an important role in the formation and control of brown fat. It may also be the case that genetic predisposition influences the development and activation of brown fat.
New treatments to combat widespread diseases
At the Department of Adipocyte Development and Nutrition (ADE) at the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), we are exploring the extent to which the formation and function of white and brown fat cells may be influenced by developmental mechanisms, as well as by entirely normal processes such as nutrition and ageing. We use mouse cells to conduct our experiments. We hope that our research work will allow treatments to combat pathological obesity and associated conditions to be developed. Our team is highly interdisciplinary in its composition: alongside biochemists, biologists, nutritionists and biotechnology specialists are involved in our research. Personally, what I am particularly fascinated by is the subject’s considerable relevance when it comes to widespread diseases such as diabetes and obesity.”
Thank you for your interesting answer, Professor Schulz.
Professor Tim Julius Schulz
is a biochemist. At the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), a Leibniz Association institute, he heads the Department of Adipocyte Development and Nutrition (ADE) and explores the control mechanisms that regulate the formation of brown and white fat cells. The objective is to research ageing-related changes to fat tissue.www.dife.de