The Royal College of Physicians of Edinburgh warned that being overweight may now be considered “the norm”.
It claimed a tax would help fund the “spiralling” healthcare costs associated with the problem.
The British Soft Drinks Association (BSDA) insisted that the case is “not compelling”.
It cited research which suggested a 20% tax would save just four calories per day.
Liverpool University chair of clinical epidemiology, Simon Capewell, is due to speak at a conference on the issue in Edinburgh later, entitled: “Obesity: A 21st Century Epidemic”.
Professor Capewell will cite Mexico as one example where a 10% sugary drinks tax is believed to have contributed to a 10% reduction in the consumption of such beverages while Finland, France, Hungary, Latvia and the USA have also introduced sugar taxes.
He said: “The revenues raised can then be invested back into initiatives to increase children’s health in these countries, as is happening in Mexico.
“Scotland has an excellent track record in addressing public health issues. Notable achievements include smoke-free public places and proposals for minimum unit pricing for alcohol. We need to explore how these developments could be repeated with sugary drinks.”
Gavin Partington, BSDA director general, said: “The efforts by soft drinks companies including product reformulation, smaller pack sizes and increased promotion of low and no-calorie drinks have led to a 7% reduction in calories from soft drinks in the last three years.
“It’s also worth noting that politicians in Belgium and Denmark rejected the notion of a tax in 2013 and the experience in France shows that while sales of soft drinks initially fell after a tax was introduced in 2012, they have increased since.”