NZ Election 2020: Jacinda Ardern says obesity 'not as simplistic' as Judith Collins suggests

Jacinda Ardern has revealed she disagrees with National leader's Judith Collins' position on obesity, saying the issue isn't as simplistic as Collins made it out to be.

On Tuesday Collins called obesity "a weakness" and urged Kiwis to "take some personal responsibility" with their weight issues.

"We all have to own up to our little weaknesses," she told reporters.

Collins said people should "not blame systems for personal choices".

While on her final campaign visit to Christchurch, Ardern was asked if Collins was fat-shaming.

"As I've said, I disagree with her position," she said. "But in fact, this is a change for the National Party. Previously under the leadership of John Key and Bill English, they did take a science and evidence base to this issue. This is another area where you can see this is not the same National Party as it once was."

Collin's comments have been in the spotlight since Tuesday, with a health advocate and obesity specialist slamming them as "disrespectful" and "unfair".

"I just had steam coming out of my ears when I heard that," Kate Berridge told Newshub.

"It's absolutely not about personal responsibility - we have a saying that our genes load the gun and the environment pulls the trigger - so it's not just about stepping away from the Tim Tams."

Collins appeared on The AM Show on Wednesday defending the comments.

"If we keep making excuses and saying, 'Oh parents are too busy,' yes of course. It doesn't actually take much to get frozen vegetables out of the freezer and pull them out and do something with them. It's not that hard."

Newshub's national correspondent Patrick Gower said Collins "made a good fist" of the interview - "but she's only talking to a core kind of audience of National voters who think that obesity is about personal responsibility".

"Judith Collins is struggling, she can't control what she's saying, she's talking about all the wrong stuff. It's over."

When asked why the topic of obesity has been focused on, Ardern said she wasn't sure.

"I don't know. I don't know. It's certainly not an issue that has come up frequently on the campaign, but when it has I've pointed to what the experts have said on this issue and it's certainly not as simplistic as Judith Collins has made out."