The data is from a health target that states DHBs must refer 95% of obese children for professional help.
Children are weighed as part of the Before School Check programme, which has a high participation rate.
Southern DHB referred 64% of obese children in results published this week, in which it ranked 13th out of 20 DHBs.
The DHB did not respond to a question about why it was difficult to meet the target. Chief executive Chris Fleming said the DHB was now at 71%.
"Southern DHB continues to work closely with WellSouth to refine a referral pathway that ensures children, their families and whanau are the centre of care, helping to ensure the best child health outcomes.
"Raising Healthy Kids is a new target and Southern DHB continues to work to identify family friendly interventions and referrals which are accessible and appropriate."
The data published by the Ministry of Health this week is from the latter part of last year, and Mr Fleming said the board’s figure had improved since then. The target was introduced last July.
University of Otago nutrition and diabetes expert Prof Jim Mann said while the target was worthwhile, it did nothing to fix the underlying environment that created child obesity.
He said the rate of obesity among southern children was about the same as the national rate.
Prof Mann said new research showing Mexico’s sugar tax was cutting consumption suggested it was worth trying in New Zealand. He was initially sceptical of sugar taxes, until he saw the evidence mounting from Mexico.
Analysis of sugary-drink purchases in Mexico found a 5.5% drop in the first year after the tax was introduced was followed by a 9.7% decline in the second year, The Guardian reported yesterday.
The Mexican tax is being carefully watched by health experts in other countries.
"It’s no more nanny state than taxing alcohol or tobacco," Prof Mann said.
"You have got the opposition saying you are going to disadvantage poor people because you’re going deprive them of their sugary drinks ... there’s just no logic whatsoever.
"The only logic is you’ve got a conservative government that’s scared of the sugar industry," Prof Mann said.
Health Minister Dr Jonathan Coleman’s office did not respond to a request for comment, but has previously ruled out a sugar tax, saying there was insufficient evidence for one.
