Introduction

Obesity is defined as being more than 20% (men) or 25% (women) overweight.  Obesity is increasing rapidly throughout the developed world, and has increased from 13% to 31% in the US in the past 30 years.  In the US, it is estimated that 63.6 million adults or 31.4% of the population are obese, of whom a significant percentage are morbidly obese.  Obesity dramatically increases the chances of developing Type II diabetes, cardiovascular disease and certain types of cancer.  The primary causes of obesity are excessive calorie intake and lack of physical activity.

Animal Models of Diabetes

There are numerous genetic models of obesity in both rats and mice, including the Zucker and ZDF rats and ob/ob and db/db mice in which obesity develops spontaneously.  There are also models of diet-induced obesity, in which the development of obesity is a induced by diet, typically a high fat, high carbohydrate diet.