Labour leader Jacinda Ardern says the National Party's position on obesity under Judith Collins is a departure from the science-based stance of John Key and Bill English.
Collins yesterday described obesity as a weakness and said people should not "blame systems for personal choices".
Asked further about her position today, she said her comments were "very real to me".
"I have seen many people actually deal with issues of obesity and show incredible strength and many other people do from time to time and we all know we have weaknesses around this, or some of us do, but it is important to not tell people that they can't take care of themselves.
"I've seen it myself and actually have done it myself and I also know there are times when you sort of let things loose a bit and that is actually not great for us and you do need to take charge."
Ardern says she disagrees with Collins' position, which is a change for the National Party.
"Under the previous National government of John Key and Bill English, they did a lot of work with Sir Peter Gluckman looking into the complexity of this issue.
"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."
National MP Mark Mitchell appeared to take a different stance on Newstalk ZB today, saying obesity was "a lot more complex" than personal choice.
"Some obesity is related directly to medical conditions, even psychological conditions that need treating, so it's a more complex issue."
Ardern says she has seen those comments.
"I think actually those comments are more in keeping with the view that was once held by John Key and Bill English ... I think this just shows that Judith Collins has taken the National Party in a different direction and perhaps not all of her team agree with her."
Collins did not seem to believe Mitchell had disagreed with her.
"Did he actually say that? I saw what he said, I didn't think he differed from my view at all actually, I just think he said it in a different way.
"Do you know what I think is amazing, is that Miss Ardern thinks that she's an expert on the National Party."
New Zealand First leader Winston Peters says New Zealand is facing a tsunami of a problem with obesity.
"Yes, we need to seriously - and a long time ago - start spending a whole lot more time, a lot more education and a far greater conversation with the ethnic groups in our country with a greater propensity to have obesity problems.
"It's not just in one group of people, it's across the whole country at this point in time and we need ... to turn our attention to it if we were ever going to ensure that they live far longer, far more practical and healthy lives.
"It is a huge issue and you might say it's a pity that it's not been at the forefront of this campaign."
He says it is not a weakness or a problem of personal responsibility.
"When you are doing two or three jobs and you've got no time to cook, and you're flat out, then you know - takeaway food and cheap food at that given the income structure of so many people that's the opportunity of first resort when it comes to food.
"People have got to understand more the society which they're dealing with and how difficult it is for so many people ... the difficulty is the lack of combined exercise with diet - and diet being the most critical thing."
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