Coca-Cola Co., PepsiCo Inc. and Dr. Pepper Snapple Group, the three largest soda companies, have pledged to decrease calories found in the beverages that Americans consume by 2025.

The companies aim to decrease calories by 20 percent through the promotion of bottled water, drinks with low calories, and smaller portions of sodas.

The agreement was reached between the American Beverage Association and the Alliance for a Healthier Generation, which was founded by the Clinton Foundation and the American Heart Association.

The pledge made is a rare move by soda makers in the ongoing battle against obesity, on top of being made during a time when the beverage industry is under heightened scrutiny.

Beverage companies recently opposed a limit on the portions of sugary drinks in New York City, and are looking to prevent a newly proposed tax that will be imposed on the sugary drinks which residents in San Francisco will be voting on in the month of November.

However, under the agreement that they voluntarily signed up for, the three companies will be marketing and distributing beverages in a method that would urge consumers to smaller portions of the drinks and to zero-calorie or low-calorie beverages. 

The companies have also agreed to provide calorie counts for over 3 million vending machines, self-serve fountain dispensers and retail coolers that can be found in points of sale such as restaurants and convenience stores.

"This is a continuation of our desire to be part of the solution," said Susan Neely, the president of the American Beverage Association.

As American consumers have started to become more conscious about their health, soda consumption has started to scale back. Since the industry's peak in 1998, the per capita consumption for soda in the United States has decreased.

According to estimates made by the Beverage Digest, which tracks the soda industry, the calories found in sodas have decreased by 23 percent from the 2000 to 2013.

Former U.S. President Bill Clinton said that the commitments made by the three soda companies "can be a critical step in our ongoing fight against obesity."

While the commitments that were made by the three soda companies will not lead to penalties if unfulfilled, the results of the pledges will be tracked by the Alliance for a Healthier Generation.

In the United States, about one-third of adults and one-fifth of children are classified as obese, according to data from the Centers for Disease Control and Prevention.

According to data from the American Heart Association, Americans have a daily intake of 20 teaspoons of sugar, which is double the amount that can still be considered as healthy.