A group of scientists found that current calorie estimates on food labels could be off by as much as 10 or 20 percent.
Dieters and nutrition enthusiasts meticulously count their calories, but what if those numbers are all for naught?
"If you just go with what's noted on a label you could be misled," Stephen Secor of the University of Alabama told MSN News.
Secor was part of a group that examined calorie labeling at the annual meeting of the American Association for the Advancement of Science in Boston. They found that calorie intake is consistently misestimated, meaning that the food labels we see at the supermarket could be leading us astray.
Secor said current estimates could be off "as much as 10 or 20 percent" for some foods.
The problem with predicting calories has a lot to do with how we process and prepare foods, and the system currently in place for estimating caloric intake.
Secor said this system, the Attwater system, is probably correct for many foods, but doesn't account for digestive and cooking processes that could affect caloric value.
"The system is … probably close to 100 years old if not more and it needs a fresh look," Secor said.
Of particular interest to Secor is how much energy is used when digesting food. He said about 5 or 10 percent of a meal's calories could be spent on digestion.
"There's no such thing as a free meal," he said. Every meal costs the body something, whether it's from chewing the food, breaking it down or excreting it.
He used the example of carrots. Raw carrots are difficult to digest, whereas cooked carrots, so soft they hardly need to be chewed, can take as much as 50 percent less energy — and calories — to digest.
Related from MSN: Raw or cooked: Which vegetables are healthier?
CHANGE NOT ON THE WAY
Still, Secor said a change to the system is probably a long way off.
"What's involved in making changes is an international effort," he said. "We're just making people aware what you're reading on a label may not be as accurate as you think it is."
He sees a future where people can use devices like smartphones to swipe labels at a supermarket and get more detailed nutritional information than is available now.
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