Researchers are struggling with what to do about the "tragedy" of overweight children - including nearly 29,000 pre-schoolers aged from 2 to 4 who are obese.
Around 9.2 per cent of children in that age bracket are obese in New Zealand, a statistic which masks even more shocking ethnic and socio-economic disparities in toddler obesity. And the problem only gets worse as they get older.
"Pre-school children (who are overweight) are much more likely to stay overweight than become normal weight," said Professor Barry Taylor. "We know that the longer you're overweight, the higher the risk of cardiovascular disease in adult life."
In the 10 to 14 age group, 10.8 per cent are obese, and in adulthood, the proportion swells to 28 per cent. At Otago University's Waistline seminar yesterday, where politicians were challenged on ideas like a 20 per cent tax on sugary fizzy drinks, much of the attention was on big-picture regulatory policies, as weight-loss schemes directed at individuals are often not very effective.
Associate Professor Rachael Taylor summarised weight-loss research to answer the question of how early in life obesity prevention should begin - partly because the Government is redirecting nutrition funding into the maternal and newborn area.
She said some programmes found no reduction while others, such as the Sydney-based Healthy Beginnings trial (which has similarities to an Otago baby and toddler programme being evaluated), were effective.
The Sydney intervention produced a significant reduction in average BMI (body-mass index) of 2-year-olds which equated to being about half a kg lighter than children in the non-intervention group.
Dr Taylor asked if it might be better to intervene in pregnancy, but said the big problem there was that nearly half of pregnancies were unplanned.
Targeting teenage girls might be ideal, "but unfortunately teenagers aren't that receptive" to nutritional and physical activity interventions.
So the population-wide measures, like taxes on sugary drinks, were most likely to make a difference.
Several other researchers threw in traffic-light labelling - to mark foods as healthy or unhealthy - as an important part of combating a food "environment" which promotes obesity.
Professor Robert Beaglehole called for a national strategy on obesity reduction - which National MP Paul Hutchison said the Government would release in months - and for a social movement, as with tobacco control, to create the climate for controls on the food industry.
"Obesity (here) is a public health disaster ... It is a tragedy at the personal, family and social levels. It's a pandemic."
Obesity rates in children aged 2-14 in 2012
• 10% of all children
• 19% of children in poorest 20% of homes
• 3% of children in richest 20% of homes
• 6% of European/other children
• 17% of Maori children
• 23% of Pacific children
• 7% of Asian children
Source: Ministry of Health