Major changes in lifestyle are needed to tackle childhood obesity, writes Dr Muiris Houston, Medical Correspondent
Childhood obesity represents the most serious health epidemic in developed nations. Historically, a fat child meant a healthy child. Indeed, some older carers still subscribe to this view, which stems from a time when a thin child who did not thrive was likely to have tuberculosis. But the pendulum has now swung to the point where a leading nutritionist has warned that the most obese children may die before their parents from premature heart disease and stroke.
How do we measure obesity in children? Unlike adults, for whom a simple formula incorporating height and weight produces a comparative index (the BMI, or body mass index), children naturally lose and gain weight as they grow. Childhood obesity is therefore usually defined as a weight 20 per cent greater than it should be for a particular age and height.
While no figures are available for childhood obesity levels in the Republic, international statistics reveal the extent of the problem.
In Australia, between 1985 and 1995, the number of seven to 15-year-old boys with obesity increased by a factor of 3.5, while the number of overweight girls had gone up by a factor of 4.6. Japanese 10-year-olds are now 2.5 times more obese than they were 30 years ago. And, closer to home, Scottish rates have doubled in 10 years.
Prof Hilary Hoey, professor of paediatrics at Trinity College Dublin and a consultant paediatrician at Tallaght Hospital, says that we have a huge problem with obesity here. "All you have to do is go to The Square in Tallaght and look around," she says, adding that, in her opinion, the extent of the Republic's obesity problem is more like that of the United States than Europe.
Dr John Nolan, consultant endocrinologist at St James's Hospital, who has a particular interest in adolescent obesity, says: "Our young adolescents with Type II diabetes are very obese - more so than the Japanese or other countries which have begun to collect data on the problem". He is currently gathering statistics on the extent of adolescent obesity here; Prof Hoey hopes to initiate a similiar study on obesity levels in younger children.
We do know that 18 per cent of our adult population is obese. The recent North/South Ireland Food Consumption Survey showed that the number of people aged 18 to 35 who are obese had grown from 4 per cent in 1990 to 13 per cent in 2001. So it is likely that the childhood obesity figures, when they become available, will at least reflect the trend among young adults.
A study of the physical activity levels of 11/12-year-olds, published last March in the Irish Medical Journal, classified only 4.2 per cent as "inactive", which compares well with other European states.
However, it noted that fewer than one-third of children in higher socio-economic groups walked to school, thus depriving them of a daily source of exercise.
How has this happened? At a basic level, clearly there is now an imbalance between children's intake of calories and their output in terms of exercise. For example, taking an extra sugary soft drink every day for 10 years will produce a 50kg weight gain. A diet based on chips and salty food will have a similar effect.
But the obesity epidemic has more subtle causes. Research has established a direct link between television viewing and being overweight, which goes beyond the mere "couch potato" effect.
The evidence is that children consume excessive amounts of "rubbish" food while watching TV, which may be related to the nature of the advertisements during commercial breaks.
Prof Hoey identifies other causes, such as how few children now walk to school, the influence of older siblings who work but who still live at home and who are a bad influence on eating habits, and the effects of parental security concerns on children being able to "go out and play". Now they sit in watching videos, where parents can keep an eye on them.
Childhood obesity is a multisystem disease: it is linked to joint problems, flat feet, gallstones, asthma, poor self-esteem and the development of eating disorders. Some of its implications deserve special attention, however.
The insulin resistance syndrome is a clustering of risk factors which have been identified in children as young as five years of age.
The syndrome includes high blood pressure, high cholesterol, an increased tendency to blood-clotting, elevated levels of insulin and a malfunction of the lining of the blood vessels, which is linked to heart disease.
Obesity in childhood doubles the risk of death from coronary heart disease in adulthood. But it is the link with Type II (non-insulin-dependent) diabetes in adolescents which is most striking. Virtually unheard of in teenagers until recently, it has now reached epidemic proportions in some countries.
The phenomenon is almost entirely attributable to the childhood obesity epidemic. It is an ominous development in view of the complications of diabetes - heart disease, stroke, limb amputation and kidney failure.
Treatment of childhood obesity problems is an exercise in prevention rather than prescription. The broad approaches are outlined in the accompanying panel. According to Prof Hoey, we need a strategy to prevent and reverse childhood obesity.
"It would only take a small amount of resources compared to the cost of treating the health complications," she says.
There have been local initiatives: the South-Eastern Health Board has established two new clinics in Carlow and Kilkenny aimed at promoting healthy eating and increasing activities for overweight children. But we clearly need a national strategy.
What changes would Prof Hoey make? She would ban vending machines for soft drinks in schools and she questions the necessity for school tuck-shops. "There should be no sweets at check-out desks in supermarkets," she says.
And she would curtail the amount, content and timing of TV advertising aimed at children.
"Prevention must start at school, with good, simple education on proper diet. The entire epidemic and its complications are preventable," she states firmly.
Clearly, the health implications of childhood obesity are immense. It is no exaggeration to say that parents could soon outlive their grossly obese children. If we are to avoid this appalling vista, then preventive action must begin now.