Soda manufacturers aren't feeling so bubbly, right now, thanks to several studies coming out this week that claim to show a direct link between soda consumption and obesity.

Will soda be the next tobacco? Some scientists and nutritionists argue that the evidence is consistent and compelling; the more soda Americans consume, the fatter we've grown. Their proposed solutions? Putting a surgeon general's warning on soda cans, or perhaps imposing a “fat tax”.

Nonsense, say other scientists, who happen to be on the beverage industry's payroll. These scientists call such remedies “laughable,” and insist that other factors are to blame, chiefly lack of exercise and bad eating habits.

The anti-soda contingent includes obesity researchers from Harvard and Yale, among them Dr. David Ludwig, a Harvard pediatrician who favors a “fat tax” on fast food and soda. Ludwig studied 548 Massachusetts school kids and found that for each sugary beverage consumed daily, the odds of obesity increased 60 percent.

In the two decades from 1977 to 1997, soft drink consumption rose more than 60 percent among adults and more than doubled in kids at the same time that obesity roughly doubled.

But why do scientists suspect that soda is the culprit behind all this corpulence? Our bodies process the calories from sugar-sweetened beverages differently than calories from food; high fructose corn syrup can increase triglycerides, those fats in the blood that contribute to heart disease, diabetes, and other illnesses.

The sugar and soda lobbies have an awful lot of clout, and they've used it, so far, to prevent the FDA from specifically recommending that we cut back on our consumption of sugary beverages.

But beverage manufacturers are on the defensive, as soda vending machines are getting kicked out of schools across the country and soda sales lose market share to sports drinks, flavored iced teas and juices.

Will soda cans someday bear a label that says “Warning: Excess Soda Consumption May Lead to Obesity?” The beverage industry may dismiss that idea as laughable, but believe me, they're not laughing.

Image credit: CDC