An Otago University food research group says a weight loss competition between politicians is sending the wrong message to people who need to lose weight.
Seven Maori Affairs Select committee members and Labour MP Shane Jones are seeing who can lose the most weight in eight weeks.
But Dr Jim Mann of Otago University says their contest may encourage people to crash-diet, and many studies have shown that is unhealthy.
He says it is better for people to make a long-tem commitment to healthy living.
However, Dr Mann says he is pleased the MPs are making an effort to lose weight.
National Party MP Tau Henare says he is making a permanent change in his diet because he was recently diagnosed with diabetes.
He says the contest is simply a way for his colleagues to support him and have some fun while they lose weight.
Mr Henare says the contest was not geared toward attracting publicity.