US public health advocates are hoping to pivot after a major setback in Chicago, where local lawmakers repealed a soda tax after only two months following fierce industry-backed lobbying.

On October 11, the Cook County Board of Commissioners, which includes Chicago, nullified the penny-an-ounce levy, which was seen as a means to discourage consumption of sugary drinks that can lead to obesity, diabetes and other ills.

"It's a setback," said Jim O'Hara, director of health promotion policy at the nonprofit Center for Science in the Public Interest. 

"It's a step back in the continuing efforts to improve public health," said Nancy Brown, chief executive of the American Heart Association.

Backed by former New York Mayor Michael Bloomberg, who has spent millions backing television ads promoting local soda taxes, the American Heart Association pushed hard to defend the Chicago measure out of worry a defeat could weaken other campaigns.

Soda consumption in the US hit a 30-year low in 2016 amid greater public awareness of the health costs of the drinks. 

About 20 percent of American girls and 23 percent of the boys are now obese, according to the World Health Organization. 

Cities that have adopted soda taxes include Philadephia, San Francisco, Seattle and Boulder, Colorado. 

O'Hara said one lesson out of the Chicago defeat was the need for political supporters and NGOs to be "very clear" in how money raised from the tax will benefit public health.

After having been caught off guard by early victories of soda tax supporters, the carbonated beverage industry has found its footing.

The industry has enlisted trade associations and local merchants such as convenience stores to oppose the measures, while at the same time directing campaign contributions to key lawmakers.

The campaigns have resulted in soda-tax defeats in several places, including the states of West Virginia and Michigan and the city of Santa Fe in New Mexico.

"People have recognized that this is a bad idea because it goes after working-class people," said William Dermody, a spokesman for the American Beverage Association, whose members include Coca-Cola and PepsiCo. 

- Hitting the consumer -

In Chicago, the Can the Tax Coalition argued the soda tax was an ill-advised penalty on consumers and small business that would do nothing for public health.

"I am living on a budget, it's becoming extremely expensive" said Detrice, an African-American woman in one of the spots. "I just can't take it any more."

Opponents of the taxes are now taking the battle to Philadelphia, raising similar issues about higher prices, lost jobs and the hit to small business, in an effort to derail the levy, which took effect in January

But public health advocates aren't backing down.

"We will continue the fight to pass sugary drink taxes across the country," said Brown of the American Heart Association.

Supporters of the measures can also take solace in shifting consumer tastes that have led to new product launches by Coca-Cola and PepsiCo of juices, bottled water and low calorie soda while cola sales languish.

Keith Ayoob, director of the nutrition clinic at Albert Einstein College of Medicine, said the answer to the problem is more public awareness of the ills of drinking soda.

"People see it as intrusive," Ayoob said of the taxes. "I would much rather focus on empowering and motivating consumers to make better choices rather than wait for legislation."