A tax on sugary drinks could prevent 3.7 million cases of obesity in the UK over the next decade, according to a report.
The figures will increase pressure on the government over its strategy on childhood obesity, which is due to be published in the next few weeks.
This is equal to 3.7 million fewer obese people.
The report also predicts that a sugar tax could save the NHS about STG10 million ($A20 million) in healthcare and social care costs in 2025 alone.
Several charities and high-profile campaigners, including celebrity chef Jamie Oliver, are calling for a sugar tax as part of a range of measures to cut obesity and the amount of sugar in children's diets.
Being overweight or obese can lead to many health problems, including cancer, Type 2 diabetes, heart disease and stroke.
Cancer Research UK is calling for a tax on sugary drinks, a ban on junk food adverts on TV before the 9pm watershed, and new targets for reducing the amount of fat and sugar in food.