“The article reflects the fact that our views on the biological function of white fat have changed dramatically over the past 10 years – from a simple fat storage tissue to a major endocrine and signalling organ.”

The paper provides a succinct overview of the highly topical, indeed "hot," area of adipokines and inflammation, adipokines being the rapidly expanding range of proteins secreted from fat cells. The article reflects the fact that our views on the biological function of white fat have changed dramatically over the past 10 years—from a simple fat storage tissue to a major endocrine and signalling organ. Interest in adipose tissue and inflammation stems very much from recent studies showing that obesity is characterized by chronic low-grade inflammation, and that this is important in the development of obesity-related diseases such as the metabolic syndrome. The article also recommends a set of terms to be used to describe the secretory products of fat cells, and proposes the novel hypothesis that inflammation in adipose tissue is a response to hypoxia as tissue mass expands.

I believe that the strength of the article lies in the combination of a timely overview of a "hot" field, together with the presentation of a novel, specific, and testable hypothesis.

We used to think that our fat cells were simply present to store lipids to use as fuel when we were short of food. However, we now recognize that these cells release hormones and other proteins which help to regulate how the body works. Some of these proteins are involved in inflammation and the article presents a clear overview of the various inflammatory factors that come from fat cells. It also suggests a possible reason why fat tissue becomes "inflamed," the idea being that some fat cells become short of oxygen as the amount of body fat increases (and the cells become distant from blood vessels) and that inflammation is an attempt to increase blood flow.

I started working on the regulation of energy balance and body weight in 1975 when I moved to the Medical Research Council, Dunn Nutrition Laboratory in Cambridge (UK). For a number of years my work centered on the importance to energy balance of adaptive changes in energy expenditure, focusing on "thermogenesis" and the biology of brown adipose tissue. In 1994 (by which time I was at the Rowett Research Institute in Aberdeen, Scotland, via the University of Alberta, Canada) I changed direction—from brown fat to white fat—with the discovery of leptin, a critical hormone in the control of body fat which is secreted primarily from white adipose tissue. After several years focusing on leptin, my research rapidly evolved to a consideration of the broader endocrine and secretory role of white adipose tissue—resulting in my present interest, and that of my colleagues, in adipokines and inflammation.