A sugar tax on soft drinks could result in thousands fewer British adults and children becoming obese, research suggests.
The proposed levy, due to be introduced in April 2018, could result in 144,000 fewer adults and children being obese.
It could also lead to 19,000 fewer new cases of Type 2 diabetes each year, and a yearly reduction of 269,000 teeth affected by decay.
The industry tax relates to the sugar content of drinks, with a higher amount charged for the most sugary beverages.
Researchers modelled three ways that the soft drinks industry might respond to the levy - reducing the sugar content of drinks, raising the price of sugary drinks, and encouraging customers to switch to drinks containing less sugar.
For each scenario they estimated the likely effect on rates of obesity, diabetes and tooth decay.
The study found that a 30% reduction in the sugar content of all high-sugar drinks - a step already taken by some manufacturers - and a 15% reduction for moderately sugary drinks could have a huge impact on health.
Passing on half of the cost of the levy to consumers, leading to a 20% increase in the price of high and mid-sugar drinks, was predicted to reduce the number of obese adults and children by 81,600, cases of diabetes by 10,800, and decaying teeth by 149,000.
Dr Adam Briggs, from Oxford University, who led the research published in The Lancet, said: "Our study provides the first estimates of the likely health impact of the UK soft drinks levy.
"The extent of the health benefits of the tax will depend on industry's response.
"We must therefore be vigilant to ensure the food industry acts to remove sugar from soft drinks, and that where the tax is passed on to consumers it increases the price of targeted products only - drinks with high levels of sugar."
Oxford colleague and co-author Professor Susan Jebb said: "In spite of the uncertainties, the direction of the effect is clear; this levy will have a positive impact, especially on children's health."
Professor Richard Tiffin, another member of the team from the University of Reading, said it was significant that children would benefit most.
He added: "Childhood obesity is a ticking time bomb and we must now turn our attention to other measures that will bring about the step change in diet that is necessary to truly tackle this issue.
"We need a much better understanding of the diverse and complex reasons people choose a poor diet."
But nutrition expert Professor Tom Sanders, from King's College London, said he found some of the claims made by researchers "hard to swallow".
He said the proposed tax would reduce energy intake by five calories per person per day, or a third of a teaspoonful of sugar.
"This is a very small reduction in energy intake - equivalent to the amount of energy expended by one minute of brisk walking," he said.