The Food and Drug Administration proposed on Friday that nutrition labels on packaged foods cite the amount of added sugars they contain as a percentage of the recommended daily calorie intake.

The proposal brought immediate criticism from manufacturers of foods and beverages, which claimed that the labels would confuse customers and that dietary limits on added sugars were not scientifically justified.

Added sugars are those not found in foods before they are produced and packaged. Federal officials recommend that Americans limit added sugars to just 10 percent of their daily calories.

Last year, for the first time, the F.D.A. proposed that companies list added sugars on nutrition labels, but consumers would have had to do the math themselves to determine the percentage of calories. Under the new proposal, nutritional labels would lay out that figure.