Chapter 80: Obesity

INTRODUCTION

A century ago, infectious diseases were the health scourge of humanity (particularly in childhood) so efforts in public health and medicine focussed on measures such as hygiene, vaccinations and antibiotics. Every four years since then, on average, the life expectancy in many developed nations increased by one full year. By the 1980s mortality due to chronic diseases began to outstrip that of infections. The 21st century has seen many other nations follow suit— notably China and India, which together comprise more than a third of the world’s population.

Obesity is prime among the emerging chronic conditions, whether viewed as a disease in its own right, or as a risk factor for other diseases: particularly cardiovascular disease, diabetes and cancer. Almost a third of Australian adults (5.8 million people) are obese, and another 6.7 million people are classified as being overweight.¹

Obesity is a complex, chronic, recurring health condition. In other words, a condition ideally suited to management in general practice. Australian patients, consistent with international surveys, indicate that they would appreciate more involvement from their GP in the management of obesity.² Maintaining substantial weight loss is important—it may even be life-saving— but it is not easy.

The general practitioner’s skills may be tested over a long period of time: encouraging initial weight loss, sustaining that weight loss and helping to overcome setbacks. Helpful ‘tools’ include brief motivational intervention, advice, encouragement, recommending support groups, coordinating allied health (dietitian, exercise physiologist, psychologist) and occasionally using medication or a surgical referral. All the while, attention must be paid to managing related risk factors and comorbidities.

The causative interaction between obesity and medical conditions can be a two-way street; for example, mechanical problems such as osteoarthritis and sleep apnoea are both caused by, and worsen, obesity. A third factor (particularly the ‘lifestyle choices’—nutrition and physical activity) can independently lead to both obesity and to a medical

condition, notably cardiovascular disease. The causative pathway has implications for treatment, because reversing obesity does not always improve health, and health may be improved without losing a gram in weight.

That being said, the usual medical goal for people with obesity is a sustained weight reduction through improvements in lifestyle, thereby improving quality of life and reducing morbidity and mortality risks.

Obesity is responsible for 80% of type 2 diabetes, 35% of ischaemic heart disease and 55% of hypertension in European adults.