The Department of Health has supported a proposed tax on sugar-sweetened beverages, saying "taxes are an excellent mediator of consumer behaviour". "Without a tax soft drinks are projected to grow 2.4% a year, predominantly among poorer people and this could lead to a 16% increase in obesity by 2017, of which 20% would be due to sugar-sweetened beverages," it said.It quoted World Health Organisation estimates that up to 20% of all healthcare spending could be attributed to obesity, through related illnesses such as Type 2 diabetes and heart disease."[The costs to the economy] would be substantial in terms of absenteeism due to obesity-related illness and attendance at health facilities, lethargy at work and other impacts," the department said.The tax, could, said the Treasury, add R11-billion to the fiscus.But the Beverages Association of South Africa has warned that the tax will cost the economy R14-billion, cause job losses and push the country into recession.The DA said it would reject the tax if its purpose was "simply to raise more revenue under the fig leaf of a public health benefit".The party's Wilmot James said if the tax went ahead, a "meaningful portion of its revenue should be ringfenced to fund medical research" on obesity, diabetes, hypertension and social habits that result in an increase in body mass index.The Treasury has strongly defended the tax. "Studies suggest that a 10% to 20% price increase of sugary beverages may be required to translate into a meaningful effect on health outcomes," said the Treasury's chief director of economic tax analysis, Cecil Morden.In the US a study published in the American Journal of Public Health found consumption of sugary drinks fell by more than a fifth in low-income neighbourhoods of Berkeley after the California city introduced a tax in March 2015. - Additional reporting by TMG Digital, Wall Street Journal..