Overweight and obese children in Ireland have a higher than normal consumption of sugary fizzy drinks.
A study of the food and diaries of more than 1,000 children aged 8-11 years old found the average intake of sugar-laden drinks was greater among those with weight problems.
The consumption was 383ml per day for overweight and obese children - a standard fizzy drink has 328ml.
The consumption of their slimmer peers was 315ml a day, according to Dr Janas Harrington of University College Cork.
The study presented to the European Congress on Obesity in Portugal yesterday said that taxing these drinks - in combination with other public health measures - could help in the fight against childhood obesity.
The sugar tax is due to come in next April. Although the worldwide epidemic has many causes, links between the consumption of sugary drinks and excessive weight gain in children have been observed.
The researchers found that almost one-fifth of children with normal energy intake were overweight or obese, compared with one-quarter of the total sample.
The majority of children drank fizzy drinks.
Dr Harrington said: "While no single measure will reverse current trends in obesity, given the high level of consumption of sugar-sweetened drinks and the lack of nutritional value of these products, action needs to be taken to reduce consumption, particularly in children.
"There is a compelling case for the introduction of public policy to reduce sugar-sweetened drink consumption in the population.
"The introduction of a tax on sugar-sweetened drinks in combination with other public health interventions has the potential to have a measurable effect on the scale of the epidemic of childhood obesity."
The research group is now set to monitor consumption of these drinks in the run-up to the introduction of the tax, and to assess the impact of the tax following its introduction.
Dr Harrington added: "It is unlikely that the introduction of the tax will have a direct short-term impact on obesity levels."
It is more likely to have indirect impacts such as reducing the consumption of these beverages.
This includes increasing consumption of sugar-free. It could lead to re-formulation of sweetened drinks and change public attitudes, he added, making it a fascinating experiment.