While one person might add an extra 150 calories to his or her daily intake with a can of soda, other people may be adding several hundred calories with several sodas a day, Katz said.
"Although I've been a supporter of the soda tax, I'm not that excited about it," said Katz, who worried that arguments about how no single unhealthy food caused obesity might lead everyone to try to exonerate each product.
"When they tell us that soda, not all by itself, is the cause to the epidemic of obesity; well, duh," Katz said. "It's time for us to say that everything that isn't part of the solution is part of the problem."
In his piece, Kent implied that other foods were just around the corner for proposed taxes.
"We at the Coca-Cola company are committed to working with government and health organizations to implement effective solutions to address this problem [of obesity]," he wrote. "But a number of public-health advocates have already come up with what they think is the solution: heavy taxes on some routine foods and beverages that they have decided are high in calories."
Kelly Brownell of Yale University said that taxes on soda and soda alone are proposed for a reason: There's more science to link soda consumption to obesity.
"With something as controversial as a tax, you want to be on sound scientific ground," said Brownell, who was a leading author on the articles in the New England Journal of Medicine recommending a tax on soda.
Brownell called the science on sugar beverages "rock solid."
"Scientific studies show that the body doesn't do very well with liquid calories," Brownell said. "So, if you consume calories in liquid food, your body doesn't tend to recognize those calories.".
So if one chooses to add 200 extra calories to his or her lunch, Brownell said, that person would compensate and naturally eat a little less at dinner if those 200 calories were in solid form like pizza or ice cream. But if the 200 calories were in beverage form, the person would eat more later on.
Brownell said he isn't supporting a tax on diet soda because the science isn't that strong.
Keith-Thomas Ayoob, an associate professor in the department of pediatrics at the Albert Einstein College of Medicine in New York City, said tax or no, switching beverages may be an easy way to cut calories for some people.
Yale's Katz said, "This CEO has a point. The truth is people blame certain foods but, in truth, it's a lot of things. I think excess calories should be singled out, I don't care where they come from. For that, each person needs to look at what they're doing,"
Katz gave the example of a patient he counseled who drank seven sweetened iced teas a day. Once she cut it out, "she started losing weight like crazy."
"If someone is not drinking a lot of soda, cutting back isn't going to help them," he said. "But if they are, the thing about soda is that it's a very easy swap -- drink water or diet soda and it cuts way back on the calories."