08 May 09 OBESITY IN DIFFERENT COUNTRIES

A more obvious, but still not statistically supported, association is the decline in physical activity levels. Although many people claim (from self reports) to be more physically active, the considered World Health Organisation view is that they could well be less active because any increase in leisure time activity may have been more than countered by the decrease in demand for physical labour as well as the decrease in incidental physical activity (the energy used to carry out day-to-day activities). Just getting from A to B requires less energy as technology and facilities improve by the year. Machine-power is replacing man-power and push-button technology is invading every part of daily life. Statistics on physical activity in most countries have not been kept to verify this assumption, but this hypothesis appears feasible. One finding, comparing the rise in obesity in the UK to the much lower rise in the Netherlands, who have a similar dietary composition, claims that the fact that 27 per cent of the Dutch use bicycles as a means of transport compared to only 3 per cent of the English may provide some explanation.

In the absence of evidence incriminating specific factors, it appears clear that increases in obesity are due to several changes in the recent human environment which allows the biological functions of fat to favour storage. Fatness obviously has an important survival function: it enables us to store energy to help get through the bad times. But like a lot of biological functions there is a range of healthy fat deposits, above and below which there is no longer any survival value, and illness occurs. It’s really only in the last three decades or less that overfatness has become so commonplace.

In Australia, since regular records have been kept from 1981, there has been a steady growth of around 0.7 per cent per year in the percentage of the population regarded as overweight or obese using a measure of BMI. This is similar to the increase in the US measured by the National Health and Nutrition Examination Surveys (NHANES) carried out at regular intervals. There appears also to be a faster rate of growth in the extreme categories of fatness and in lower socioeconomic (SE) groups. Obesity in Australia for example, has doubled in the last decade with around 10 per cent of Australians now regarded as obese. The majority of these are from lower SE groups. The Australian Institute of Health estimates that around 5 million Australians are now overfat (including the more severe category of obesity). In North America and Europe the estimate is 50 and 100 million respectively. This has led National Heart Foundations in the Western world to be concerned about reversals of gains made in heart disease prevention through increases in obesity.

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