It ain’t the meat, it’s the motion
by Michèle Nardelli
It
is possibly one of the most hotly debated health issues of the day – the
rapid climb to obesity in western societies has been drawing headlines
since the alarm bells first rang in the 1990s.
Figures released in the latest National Health Survey (February 2006) show that about 60 per cent of Australians are either overweight or obese. Particularly alarming is the rise in childhood obesity.
Debate over the causes of the obesity epidemic has polarised into two camps - those who say kids are eating much more food and more bad food, than they used to - and those who say that kids are much less active than they used to be.
In all the hue and cry over the statistics, politicians and the media have been quick to jump to conclusions - kids are fat because of their parents, kids are fat because they watch too much TV, kids are fat because advertisers keep selling them bad foods – the list goes on.
In some of the most comprehensive historical research done in the field to date, UniSA’s Associate Professor Tim Olds has been looking at children’s diets since the 1880s in a bid to shed light on the historical development of weight gain.
“I am trying to track down every study ever done in the developed world on the energy intake of children from 0 to 18 years,” Prof Olds said.
“So far that incorporates 1,400 reports which take in the eating patterns of 230,000 children from 24 countries since about 1882.
“The patterns in reported food intake are clear. Just at a superficial level the research shows that children were eating much larger quantities of food in the past – for example very large amounts of bread and potatoes. There has also been a much greater variety of food eaten since the WWII.”
But looking a little deeper and at more recent data, Prof Olds found that since the 1950s children’s reported calorie intake has declined by four to five per cent every 10 years.
“Reported” is an important word in all of this because as Prof Olds is quick to point out, good research will entertain the possibility that self-reporting might not be accurate.
“People tend to under report the amount they eat, and people who are overweight, people who snack and people who are dieting tend to under report their eating more,” he said. “However, when you take into account the effect of increased fatness on under reporting, it doesn’t come near to accounting for the decline in reported eating. There still seems to be a decline of about three per cent per decade.”
If this reported decline reflects real changes, Prof Olds says it would mean our children are eating about 10 per cent less than we did when we were their age.
What’s more, children’s diets seem to be improving. Reported fat intake has dropped from about 39 per cent of calories in 1960 to less than 35 per cent today. Both kids and adults are eating less saturated fats.
So if kids are eating better food and less food, why are they getting fatter?
“This is paradoxical,” Prof Olds said. The only way kids can be eating less and still get fatter is if they are using up less energy.”
But can activity levels have dropped so dramatically?
“Based on data we have about children in 1960 and children today, if we replace one hour of walking to school, as many children did in the 1950s and 1960s with an hour in a car, and one hour of playing soccer with an hour of playing video games each day – that would account for the increase in weight,” Prof Olds said.
“None of this means children can forget about diet. If children are still getting fatter then they are eating more than they need to.
“The truth is that we can’t turn back the clock to a time when everything about our lives involved a lot more personal energy use.
“The equation is simple – even if children are eating less than they used to, they are still taking in more energy than they are using.
“We need to think laterally about the problem - look at ways to develop more, high micro-nutrient, low-calorie diets and foods that fit that bill too. At the same time we need to be doing everything we can to increase children’s activity levels.”