WHO urges taxing sugary drinks, but are such measures effective?

The International Council of Beverages Associations stated that while it supports the WHO efforts to combat obesity, "we believe a comprehensive approach including emphasis on the whole diet is necessary to achieve a real and lasting solution."

It also stated that, "ICBA believes that all of our products can be part of a healthy lifestyle."

Health advocates propose taxing soda, sugary juices and sports drinks, much like a sin tax. Several countries and cities have already headed in that direction.

Next month, voters in San Francisco, Oakland and Boulder will decide whether to levy taxes on sodas and sugary drinks in their cities. If the measures pass, they would follow in the footsteps of Berkeley and Philadelphia.

Berkeley became the first US city to pass taxes on sugary drinks in 2014 after voters overwhelmingly passed the measure. The 1-cent-an-ounce tax raised the price of a soda can by 12 cents and a two-liter bottle by 68 cents.

After the sin tax went into effect, Berkeley residents reported a 63% increase in drinking water and a 21% drop in soda and sugary beverage consumption, according to a 2016 University of California Berkeley study.

"The soda tax appears to be an effective tool," said study senior author Kristine Madsen, an associate professor of public health at UC Berkeley in a statement. "Not only was the drop in sugary drink consumption in Berkeley greater than we expected, the apparent shift to less harmful products like water is a very good sign."

Philadelphia became the second city to approve a soda tax, which goes into effect January 2017.

The soda taxes represent a different approach after a failed attempt in New York to restrict the size of soda cups. City health officials attempted to ban sugary drinks of more than 16 ounces in restaurants, movie theaters and food service establishment in 2013. An appeals court struck down the restriction calling them "arbitrary and capricious" -- a ruling welcomed by the American Beverage Association.

Mexico has seen somewhat mixed results after instituting a 10% tax on sugary drinks in 2013. It was the same year that Mexico ranked as the world's most overweight industrialized nation, according to the UN Food and Agricultural Organization.

That year, the WHO estimated that the average Mexican drank 163 liters (about 43 gallons) of soda a year, making Mexico the largest consumer of soft drinks in the world.

A British Medical Journal study found that purchases of taxed beverages fell by 6% in the first year, while sales of water and non-taxed beverages rose by 4%. However, the improvements and differences in sales have been contested by some experts.

The Wall Street Journal reported earlier this year that soda sales were climbing in Mexico after an initial dip after the tax went into effect.

Hungary's taxes extend beyond sugary drinks. In 2011, the country imposed taxes on foods and drinks with high sugar, salt or caffeine content. Items like candies, sweets, soft drinks, energy drinks and alcoholic soda beverages carry a "public health product tax."

The purpose was to redistribute responsibility for "unhealthy food choices so that individuals bear a proportional share of the social and economic burden of unhealthy eating," according to a WHO brief.

Since the tax went into effect, Hungarians ate less unhealthy products and about 40% of the food manufacturers either stopped selling the junk food or changed the ingredients, according to a national survey. Surveys found that people drank less sodas and energy drinks because they didn't want to pay higher prices.

Elsewhere in the world, the UK announced plans this year to charge a soda tax to curb childhood obesity. Countries including the Philippines, South Africa and Northern Ireland are also mulling similar taxes.