That's the good news - or bad news, depending on how you look at it - in a recent Food and Drug Administration study. It found that, in fact, there is truth in those little package labels you peek at before ripping into a bag of munchies.

FDA food police descended on grocery stores across the US for samples of 300 of Americans' favorite foods - from Del Monte fruit cocktail to Wonder hamburger buns. Some 2,000 lab tests later, the FDA had its result: Nutrition labels that list calorie, fat, protein, carbohydrate, and other nutrients are accurate 91 percent of the time. That's up from 87 percent in 1994, when such information was first required and checked.

The results represent a victory for proponents of the Nutrition Labeling and Education Act, passed in 1990 to give consumers consistent and understandable information about the foods they eat. The surveys also benefit the food industry by acting as a check on fair competition, says the FDA, America's top cop of truth-in-labeling.

So, which labels may need adjusting? The Klondike bar, for one, which its maker advertises as "America's No. 1 selling ice cream bar." It sports a label that says 290 calories, but the FDA analysis puts the count at 550. It also has 30 grams of fat, according to the FDA, not 20 as the label reports.

"There is a difference in the interpretation of the serving weight, so we are doing whatever possible to identify where the difference lies," says a spokeswoman for Good Humor-Breyers, maker of the ice cream treat. "We are very eager to rectify the situation."

Still, overall results indicate widespread compliance with the 1990 law. "Consumers count on the food label to get reliable nutrition information," said Donna Shalala, secretary of Health and Human Services. "These results show that this confidence is well-placed."

"The boost [in accuracy rates] from 1994 to 1996 confirms consumers can have confidence in nutrition labeling," agrees Robert Earl of the International Food Information Council here. "It confirms that nutrition information on food labels is reliable and very useful for consumers for comparing similar food products to make personal choices."

Besides the Klondike bar, the FDA labs turned up a few other discrepancies between labels and reality. Some foods, notably frozen shellfish and ocean perch, contain more cholesterol than reported. The FDA found that Sau-Sea shrimp contain 115 grams of carbohydrates, not 25. And two brands of frozen ocean perch fillets - Sea-Pak and Taste O'Sea - contain 65 grams of carbohydrates, not 20 and 45 as their labels indicate. The label for a Garden Burger meatless patty lists 5 grams of carbohydrates, but the FDA lab found twice as many.

The largest differences between labels and laboratory testing are in quantities of iron and vitamin A, with 69 percent and 54 percent laboratory-to-label consistency, respectively. But the FDA acknowledges that the differences may be attributed to difficulties in developing standardized methodologies for analyzing these nutrients.

Calorie counts are not usually disputed though, says FDA spokeswoman Judy Foulke. The FDA is reviewing the study results now and will contact companies that are not in compliance.

"Manufacturers take food labels seriously because we take our consumers seriously," says Stephen Ziller of Grocery Manufacturers of America. "These continued improvements showcase the positive results that can be achieved."

Standardization of food labeling has its roots in Americans' increased attention to diet. The 1990 law, among other things, requires food labels to show how a product fits into overall recommendations for a daily diet.

"We lobbied for the ... nutrition-facts label because consumers need this information ... to choose healthier foods," says Bob Hahn of Public Voice for Food and Health Policy here. "It has been a tremendous success, as the FDA and consumer studies research bears out."