Our fizzy drinks are among the worst in the world when it comes to sugar content.

A Waikato University study has found New Zealand's fizzies contain more sugar than those in most other Western countries.

Fizz founder Dr Gerhard Sundborn said the findings are further proof a sugar tax is needed.

He said the study's results weren't surprising considering New Zealand had the third highest obesity rate for adults in the OECD.

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Sundborn told Newstalk ZB's Chris Lynch New Zealand fizzy drinks and juice average one-and-a-half-times more sugar than Canada, Australia and the US.

He says there's no real regulation around sugar or its industry, and it's time for that to change.

Consumer New Zealand's chief executive Sue Chetwin believes the amount of sugar found is "shocking".

"But then I think our government hasn't done very much in this area and I guess the manufacturers know that and they're pushing as hard as they can."

She says self-regulation doesn't seem to be working, along with the health star rating system.

"I think a sugar tax where the manufacturers actually have to pay to add the sugar to their drinks... will make them think twice," Chetwin says.

"In the UK, that's going to be introduced in April this year and already the manufacturers there are reformulating and dropping sugar because they know they'll have to pay."