Sugary drinks are helping fuel the obesity epidemic in the United States, according to an article in the October Harvard Health Letter. Americans consume 174 liters of sweetened beverages a year, or double the amount consumed 30 years ago.

Adolescents have the worst habits overall. Between 10 and 20 percent of their daily caloric intake is from sugary drinks. Harvard epidemiologist and physician Carlos Camargo says sweetened colas, teas, lemonades, sports and energy drinks have no nutritional value. "There [are] no vitamins or minerals. There is nothing else that comes along with that water except for calories."

Camargo says good nutrition depends on diet and exercise. "You need to exercise and you need to remove unnecessary calories and there is no better place to start than with the number one contributor of calories in the diet of many Americans, which is the sugar water."

The Harvard Health Letter documents the link between sugary drinks and weight gain, which Camargo says the beverage industry has slowly come to acknowledge . "The last two or three years there has been a shift in the industry as legislatures around the country are basically figuring out ways to ban soft drinks from schools. They have come around to think that maybe there is a little excess consumption. And I think that is a promising sign."

The Harvard Health Letter recommends several more healthful and non-fattening alternatives to sugary drinks, including low-calorie beverages such as unsweetened teas, coffees, seltzers and, yes, plain old water.