14.02.1 Introduction

Obesity is derived from the Body Mass Index (BMI), which is body weight in kilograms divided by square of height in metres (kg/m²). If you have a BMI of 30 kg/m² or more, you are obese. A BMI in the range of 25-30 kg/m² is considered to be overweight. Obesity is a risk factor for many disorders (Figure 14.5). Thus, obese people are more likely to develop diabetes or the metabolic syndrome. The metabolic syndrome is often a precursor to diabetes, and is a combination of obesity, raised triglycerides plasma levels, raised plasma glucose levels and hypertension. Obesity, the metabolic syndrome and diabetes are, in turn, risk factors for cardiovascular diseases such as atherosclerosis, hypertension, and venous thrombosis (all of which are risk factors for angina and heart attacks). Obesity, the metabolic syndrome and diabetes are also risk factors for cerebrovascular disease such as stroke.

Figure 14.5 Obesity as a risk factor (Copyright QUT, Sheila Doggrell)

Obesity is now recognised as a disease, and not necessarily a character flaw. There is a genetic contribution to obesity, which varies from person to person. There are also environmental factors that contribute to obesity, and these include an increased caloric intake and decreased physical activity.

Obesity should be managed with diet and exercise. When diet and exercise do not work alone, they should be used in combination with pharmacotherapy. There are two approaches to reducing body weight. The first is to decrease energy intake, and this can be achieved by dieting or by using certain drugs. The second is to increase energy expenditure, and this can be achieved by physical activity or by using certain drugs.

Even relatively small reductions in body weight are good for you. Thus, a 5-10% weight loss leads to about a 60% reduction in the rate of type 2 diabetes.