LONDON (AP) - Slapping a 20 percent tax on soda in Britain could cut the number of obese adults by about 180,000, according to a new study. Though the number works out to a modest drop of 1.3 percent in obesity, scientists say that reduction would still be worthwhile in the U.K., which has a population of about 63 million and is the fattest country in Western Europe. About one in four Britons is obese. Researchers at Oxford University and the University of Reading estimated a 20 percent tax on soft drinks would reduce sales by 15 percent and that people would buy beverages like orange juice, milk and diet drinks instead. They said the tax would have the biggest impact on people under 30, who drink more sugary drinks than anyone else. No funding was provided for the study, published online Thursday in the journal, BMJ. "Every possible alternative that people would buy is going to be a better than a sugary drink," said Mike Rayner of Oxford, one of the study authors. (The tax) is not a panacea, but it's part of the solution. Rayner acknowledged the government might shy away from introducing such a hefty tax at a time when the economy is still shaky. Last year, Britain's Conservative-led coalition had to backtrack on a sales tax it planned to levy on fat-laden meat pies after a public outcry. Such soft drink taxes have been used or considered elsewhere, including France, Mexico, Norway and some U.S. states, but previous analysis of them have found mixed results on people's drinking habits. In the past, the U.K. has relied on convincing businesses to make their products healthier as opposed to resorting to taxes; that strategy reduced salt levels in processed foods by 20 to 50 percent. Last week, Britain announced another government-led initiative, in which several major food companies promised to cut the amount of saturated fat in their products. Critics slammed the deal and said the U.K. shouldn't rely on voluntary measures to fight the country's growing waistlines. "We are at the mercy of these (food and drink) companies," said Tam Fry, spokesman for the National Obesity Forum. Fry was not linked to the BMJ study and said the proposed 20 percent tax would be a hard sell. Instead, Fry said the government should simply fine companies if they exceed a certain threshold for the amount of sugar allowable in food and drink. "Companies should be coerced with fiscal measures rather than punishing the consumer with taxes," Fry said. "We are in such a predicament with obesity in this country that we have to put the pussy-footing measures to one side," he said. It's time for the stick to come out.