Like many parents, Steve Mulligan looks at nutrition facts for help. But those numbers are based on one thing: serving size.
"We don't normally use the serving size as a guideline just because it tends to be kind of confusing," Mulligan said.
Many health experts agree and are calling for the Food and Drug Administration to revise serving size regulations, which are based in part on eating behavior surveys from the 1970s and '80s.
"People are eating much larger portions than they used to, so these numbers don't really reflect what people are typically consuming in one sitting," said Elisa Zied, dietician and author of "Nutrition at Your Fingertips."
Zied says this leads many to believe they're consuming fewer calories, fat and sodium than they are.
A recent survey by the Center for Science in the Public Interest compared serving sizes on labels to average consumption and came up with the worst offenders: ice cream, soup and non-stick cooking spray.
For example, a typical serving of ice cream is half a cup, but most scoop twice that much, racking up a day's worth of saturated fat.
And who uses cooking spray for the recommended one-fourth of a second?
"You might compare five different kinds of cereal and find that one serving on one package is one cup and another serving might be a half a cup. So that makes it really tricky, and people just don't have the time, or typically don't make the time, to do all the math," Zied said.
Former FDA official Peter Pitts says it is a long and arduous process for the FDA to change anything on the food label.
"You need to find the science. You need to reach consensus with outside experts," he said.
Pitts wants change, but says portions are just one piece of the puzzle.
"So the really crucial thing is not to redefine what a serving is, it's just a number, but rather to help educate people as to what the appropriate amount of food they should intake and what kind and when," he said.