Sep 25, 2006, 4:30 GMT
Sydney - Blame Ronald McDonald for an obesity rate three times what it was 10 years ago?
No, it's a lack of exercise that has puffed out our kids, says Australian health expert Tim Olds.
A review of the literature that encompassed 1,700 studies from around the world into changes in children's eating habits over the last 30 years convinced him that the disparity between energy-input and energy-output is the culprit behind the growing girth rate.
'No matter which way you turn the data, kids are eating less than they used to,' Olds said. 'I think it's the energy-out side of the equation that's been affected.'
He pointed to a sharp decline in incidental exercise, with most children being driven to school and more of them choosing to sit indoors rather than play outside.
Olds, from the University of South Australia, noted that the average 12-year-old Australian boy in 2006 was 7 kilograms heavier and 25 per cent fatter than his 1970 counterpart.
Yet the fat content of diets reached a peak in 1965, when it accounted for about 40 per cent of total daily kilojoules. Now, the fat component in most developed countries is now about 35 per cent.
Between 1955 and 1985 energy intake fell by 4 per cent per decade. There was a further flattening out in energy intake between 1985 and 1995.
'These results are very surprising given that these apparent decreases in energy intake were occurring at a time when childhood overweight and obesity were increasing rapidly,' Olds said in a paper published in the journal Australasian Science.
'If energy intakes really were declining, there must have been drastic declines in energy expenditure.'
Perhaps the most worrying finding was that energy intake may be rising again. 'If these trends are confirmed, children face the double impact of reduced energy expenditure and increased energy intake,' he said.
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