Public health researchers say the government is showing a lack of courage by not introducing a tax targeted at sugary drinks.

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A new study: Obesity: Are Liquid Sugars Different from Solid Sugar in Ability to Cause Metabolic Syndrome published in the medical journal Obesity reviewed previous research, which found sugar in drinks was more harmful than sugar in solid food.

"This is due to its concentration, quantity and the speed with which sugar is metabolised when consumed in liquid form rather than solid," Dr Gerhard Sundborn, from the University of Auckland's Faculty of Medical and Health Sciences said.

"You don't compensate by eating less sugar so it's kind of like a double-whammy."

Dr Sundborn said the results of the research presented a strong case for a tax on drinks.

"I think the government lacks a bit of courage and leadership to bring in something like this because like we've seen elsewhere in the world, they've been brought in in the UK, Mexico and a number of states in the United States - and they work."

The study found that New Zealand's consumption of drinks increased from 2002 to 2016, compared to the United Kingdom and United States where consumption is steadily falling.

New Zealanders are drinking fewer soft drinks, but more juice, sports and energy drinks - an average 'power' or energy drink contains about seven teaspoons of sugar per cup, compared with six teaspoons in fizzy drink.