Obesity is the modern health epidemic of Western society. The World Health Organisation estimated in the year 2000 that as many as 300 million people worldwide are clinically obese. European countries are now following the worrying trends set by our American neighbours with as many as 30% of adults now classified as overweight and obese (Table 1). In the recent British Women's Heart and Health Study over 4000 women from 23 towns in England, Scotland and Wales were surveyed to establish the prevalence of cardiovascular risk factors. Over one quarter of the participants were obese (Body mass index (BMI)>30 kg/m2) with the mean BMI of the sample being 27.7 kg/m2 (SD 5.2). One fifth of the women were inactive (participated in less than one episode of moderate activity per week) and two fifths of women did not eat a portion of fresh fruit at least daily. In Sweden, 5600 individuals were surveyed to assess the trends for lifestyle changes between the periods 1986 and 1994. The prevalence of obesity (BMI>30 kg/m2) increased from 6.1% to 9.8% and overweight (BMI 25–29.9 kg/m2) from 19.6%–29.1% in women over this time period. In support of this the proportion of leisure time physical inactivity increased from 19.4% to 26.7%. Perhaps of more concern is the alarming increase in the prevalence of obesity in children. Data from a nationally representative sample of 2630 English children showed that the frequency of overweight (>85th centile) ranged from 22% at age 6 years to 31% at age 15 years and that of obesity (>95th centile) ranged from 10% at age 6 years to 17% at age 15 years. Obesity rates also vary in different ethnic groups with Afro-Caribbean and Pakistani girls living in the UK being more likely to be obese than the general population (OR 2.74 (95%CI 1.74–4.31), OR 1.71 (95%CI 1.06–2.76) respectively. A recent study has suggested that these concerning statistics may not be totally attributable to poor diet but also to a decline in total energy expenditure. For example, at age three the median time spent in sedentary behaviour was 79% of monitored hours and 76% by age five. In general these children spent only 20–25 minutes per day in moderate to vigorous physical activity. The most severe consequences of these observations is the fact that type 2 diabetes, once virtually unheard of in adolescence, now accounts for as many as half of all new diagnoses of diabetes in some populations in North America.