Serving sizes on today’s nutrition labels are unrealistically small, leading consumers to believe they’re eating less food than they actually are, says a leading food industry watchdog.

This week the Center for Science in the Public Interest (CSPI) called on the government to update the standard serving sizes for food, which it says are much lower than the amount Americans really eat in one sitting.

Labels on canned soup, ice cream, aerosol cooking sprays and powdered coffee creamer are among the most misleading, says the group.

“A ridiculously tiny serving of a third, a quarter, or even a fifth of a second spray helps PAM and other aerosol cooking sprays boast zero calories and zero fat, even though the products are mostly fat,” CSPI said in a press release.

Canned soup claims to contain 2 servings of soup, but 64 percent of Americans eat the whole can in one sitting, according to a 2010 study commissioned by CSPI. This means they eat 2,390 mg of sodium rather than the 790 mg printed on the label.

In a letter to FDA commissioner Margaret Hamburg last month, CSPI demanded that the agency update its Reference Amounts Customarily Consumed (RACC), the current regulations governing standard serving sizes, which are based on studies conducted in the 1970’s and 80’s.

In 2005, the Food and Drug Administration (FDA) issued a proposal to update average serving sizes, but has not taken any further action to change these amounts since that time.

“Six years later, FDA has not improved the regulations and the obesity epidemic continues to plague two-thirds of American adults,” says the letter.

“The FDA needs to correct serving sizes so they’re reasonably accurate,” said Michael F. Jacobson, executive director of CSPI, told Food Safety News. “We’re urging them to use common sense, and we pointed out a few where the current servings clearly are nothing like what people consume.”

The letter also calls on FDA to take action against companies who label containers consumed in one sitting as multiple-serving foods.

“If the FDA sees products that are clearly mislabeled the FDA should stop that,” Jacobson said.

The agency is currently considering a new set of nutrition labeling guidelines that would include an update in serving sizes. The proposed rules are expected to be released by the end of the year.