It sounds like a simple question. What is obesity? But like most simple questions, the answer is not as obvious as it may seem. The US Centers for Disease Control and Prevention calls obesity "A national epidemic causing higher medical costs and a lower quality of life." The CDC also notes that obesity is a contributing cause of many other health problems, including heart disease, stroke, diabetes and some types of cancer.Understanding the relationship between obesity and breast cancer can become located. Not only is there the question of measurement. Is the traditional view of body mass index always accurate or sufficient? But also, important questions around assessing risk. How might the measurement of body composition and blood based factors associated with fat inflammation help develop more precise cancer risk assessments and prognostic strategies? Dr. Neil Iyengar is at the forefront of researching and addressing these questions. He studies obesity, and in particular its relationship to breast cancer. Dr. Iyengar is an assistant member and attending physician in the Breast Medicine Service of the Department of Medicine at the Memorial Sloan-Kettering Cancer Center.He is also an associate attending physician at the Rockefeller University. In our conversation, Dr. Iyengar noted that he grew up in a family that certainly emphasized science, but where the human component was also central. You'll hear both sides of him in our talk. What is obesity? That's where we started.