Causes of obesity

Abstract

AbstractObesity is an increasingly common problem that is recognised a disease by the WHO. It is a major risk factor for the development of type 2 diabetes because it causes insulin resistance and is associated with physical inactivity. Obesity develops when energy intake exceeds energy expenditure over a prolonged period of time, leading to an accumulation of body fat. Body weight is regulated by the hypothalamus, and there have been many recent advances in understanding of energy balance that might help understand why some individuals develop obesity, and lead to new treatments. Both genetic and environmental factors contribute to the development of obesity. The recent identification of rare single gene defects that cause severe early onset obesity, such as deficiency of the hormone leptin, demonstrate that genetic factors can be powerful determinates of body mass. However, obesity has been increasing rapidly throughout the world in the last two decades, so it seems unlikely that this change has a genetic basis. It seems more plausible that the increasing weight of most populations is an appropriate biological response to an abnormal environment, characterised by easy availability of cheap, energy dense food, coupled with a massive decline in physical activity levels in the population. The challenge in preventing type 2 diabetes is to reverse these trends, and help those already obese to adopt a lifestyle that encourages weight loss, including a healthy diet and greater physical activity. Copyright © 2001 John Wiley & Sons, Ltd.