Even though the companies that made the commitment represent most of the nation's most well-known food companies, they sold only around a third of all packaged foods and beverages at the beginning of the study. Missing are many off-label brands sold under the names of retailers, and it's unknown whether those products have changed.
It is also unclear how the reduction in calories translates into consumers' diets. When the companies made the pledge in 2010, they said one way they would try and reduce calories would be to change portion sizes in an attempt to persuade consumers to eat less. The companies also said that they would develop new lower-calorie options and change existing products so they have fewer calories.
Evidence of those efforts are visible on any grocery store shelf. Many products now come in lower calorie versions, are baked instead of fried, or sold in miniature as well as larger versions.
Marks says he believes that companies' efforts to package smaller servings — 100 calorie packs of popular snacks, for example — and smaller cans of sugary drinks may have contributed to the reduction in calories. He says the main contributors most likely were the public's increasing willingness to buy healthier foods and companies responding to those consumers.
The companies involved are all part of an industry coalition of food businesses called the Healthy Weight Commitment Foundation that has organized to help reduce obesity. The foundation pledged to reduce the calories as part of an agreement with a group of nonprofit organizations and made the 2010 announcement as part of first lady Michelle Obama's Let's Move campaign to combat childhood obesity.
Lisa Gable of the Healthy Weight Commitment Foundation says the study's findings "exceeded our expectations."
She said the companies achieved the goal by coming together and also competing to make new lower-calorie foods. Market studies have shown that many of the healthier foods have outperformed other products, she said.
"This is a very significant shift in the marketplace," Gable said