Obesity is increasing in the US population and currently affects one-third of adults. The physiology of obesity is complex and predisposition to obesity is influenced by multiple genes and environment. Obesity may be measured by body fat percentage, body mass index (BMI), or visceral adiposity. Life insurance companies generally use height and weight (build) determinations. The purpose of this paper is to review the life risks and physiology of obesity, and to suggest that the current trend to liberalize traditional build table ratings may not be prudent. A case history will be utilized to demonstrate these points.