"We are excited about this report because we have exceeded our goals," said Lisa Gable, president of the Healthy Weight Commitment Foundation. "This really speaks to the competitive nature of this market," she added.
For his part, Marks said he hopes this effort will reach beyond these 16 companies and that others will get on board with the program and start reducing calories in their products.
Nutrition experts said it's not yet clear what long-term effect the calorie cuts will have on health.
"This is a step in the right direction toward changing our food environment. Only time will tell just how much of an impact it might have on American waistlines," said Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas.
"It is good to see the food industry working together to help people make healthier choices," she said.
Samantha Heller, a senior clinical nutritionist at the NYU Langone Medical Center in New York City, cautioned that calories are only one factor when it comes to eating a healthful diet.
"Let's remember that health is a complex process and is not just about calories," Heller said. "Consuming fewer calories will help with weight management, but how have the changes food companies made to their products affected the salt, fiber, chemical additives and preservatives or artificial sweetener content of the foods?" she added.
"Better-for-you-foods seem to be trending now. 'Better than what?' I might ask. I hope they really are healthy-for-you-foods that everyone can enjoy as part of an overall healthy diet," Heller said.
Of the 40 companies that founded the Healthy Weight Commitment Foundation in 2009, 16 took the pledge, according to an RWJF news release.
These 16 companies, however, accounted for 36 percent of the calories in all packaged foods and drinks sold in the United States in 2007, the news release noted. Their products include cereals, snacks, canned soups and bottled drinks.
Dr. David Katz, director of the Yale University Prevention Research Center, also took issue with focusing only on calories and not quality.