Obesity: Causes and Consequences

Abstract

is a nutrition scientist and a registered dietitian and has a particular interest in the role of dietary risk factors in the aetiology and treatment of obesity and its related metabolic diseases. Obesity is a condition of excess body fat, although it is usually defined on the basis of body mass index (BMI) or waist circumfer-ence (Figure 1). Obesity is arguably a predictable response to the modern world for an organism whose evolution is characterized by periods of famine. The broad public health problem of obesity can be usefully described as a failure of innate physiological body weight control mechanisms in the face of overwhelming environ-mental influences that favour sedentary lifestyles and energy-dense diets. It is increasingly necessary for individuals to develop cogni-tive strategies and practical skills to control their weight and avoid the adverse consequences of excess weight. The prevalence of obesity is rising around the world, but the rate of increase in the UK is generally greater than in other parts of north-western Europe. • In 1980, 8% of women (6% of men) were clinically obese, with a BMI >30. In 2002, this had trebled to 23% of women (22% of men). The prevalence of overweight (BMI 25–30) is also rising, but overweight is less common in women than men, affecting 33.7% and 43.4% respectively • The prevalence of morbid obesity (BMI >40) is also increasing sharply and now exceeds 2% of the female population. Figure 2 illustrates the trends in overweight and obesity in women (aged 16–64 years). The gender differences in the UK are modest, but in other parts of the world there is often a higher level of obesity among women. This is particularly true in the Middle East and Africa, where social and cultural values account for dif-ferences in the preferred body shape and size. In the Gambia in West Africa, the prevalence of obesity in urban women (35–50 years old) is 50% and in men (35–50 years old) only 6%. In recent years, there has been an increase in the prevalence of obesity in children and young people. Data from the Health Survey for England 2002 show that 7.2% of girls (5.5% of boys) aged 2–15 years are obese, and a further 16.3% and 20.3% over-weight. 1 The development of excess weight at a young age raises particular concerns for later health risks.