Posted Calorie Counts Are Not Very Accurate

One of the provisions of Obamacare is that all restaurants with more than 20 locations are required to post the number of calories in their menu items. (Even though Obamacare was passed in 2010, the requirement doesn’t go into effect until the second half of 2013 because of red tape: the FDA had to first come up with regulations, hold discussions on them, get final approval, and then publish them for six months before they take effect.) Most people that aren’t in the business of selling junk food see this as a great step forward in helping people realize exactly how much stuff they’re eating. But, the system is far from perfect.

200 calories' worth of apples. Photo from wiseGEEK.


The government-sanctioned way of figuring out how many calories are in food — and so far, the only practical way to do it at all — is called the Atwater System, and is named after the chemistry professor at Wesleyan who developed it around the 1890s.  Mostly, it involves burning food in a bomb calorimeter to figure out how much energy it has, and subtracting what’s been left over after digestion. But, according to NPR, this process has some flaws:

  • Processed and unprocessed foods are treated the same, even though our bodies would extract more calories from processed foods, which have in effect been pre-digested. Meaning that if two foods have the same number of calories on the label, if one of them is raw (like fruits and rare steak), your body will end up with less of its calories than the processed one (like candy and hamburgers).
  • Processed carbohydrates are particularly bad because they don’t make us feel full. The calories from a chicken breast will keep someone full a lot longer than the same calories in a chocolate bar.
  • There are also upsides though, because for some foods, the body spends a lot of energy digesting them — or doesn’t get as much energy out of them for various reasons — making the caloric count on the label higher than what you actually end up with.

200 calories' worth of Hershey's Kisses. Photo from wiseGEEK.


So even if the number of calories on the label or menu accurately showed the amount of raw energy in food, they don’t accurately represent how much of that energy our bodies absorb, or how long that energy will last us.

And as it turns out, the labels are not likely to even be accurate. In New York City, most food already has to have caloric labels, so Casey Neistat — the filmmaker who, among other short films, made an interesting video a few months back about how toothless the NYC soda ban really is — decided to test their accuracy. He took five items that he was likely to eat in one day to a food lab and had their energy measured. All but one came in over their stated number of calories:

  • a yogurt muffin actually had 735 calories instead of the 640 on the label
  • a Starbucks coffee had 393 instead of 370
  • a Chipotle burrito, 1295 instead of 1175
  • a tofu sandwich, 548 instead of 228
  • a Subway sandwich, 351 instead of 360 — the only item that was under

Starbucks and Chipotle you can forgive, because no matter how hard the employees try, no two coffees or burritos will be the same. Subway came in under that amount most likely for the same reason. But the muffin and the tofu sandwich were pre-packaged and probably should have been closer to their goal. Part of the problem is that New York City doesn’t enforce the accuracy of the calorie count — only their presence.

But regardless of blame, at the end of the day Casey ate 3321 calories instead of the 2773 calories the labels showed. That’s 549 extra calories that he didn’t intend to eat and wouldn’t have accounted for; as he points out in the video below, it’s the equivalent of a McDonald’s Quarter Pounder with Cheese, or two donuts.

The take-away? Calorie counts on the nutrition labels are not very accurate, and even if they were, they still wouldn’t represent how many of those calories your body gets, or how long it will keep hunger at bay.

At best, the number is a guideline that opens our eyes to unbelievable truths, like that a donut is the equivalent of two grilled chicken breasts. In that way, counting calories is like a very poor window thermometer that tells you if it’s warm or cold outside, but its temperature can be off by a few degrees. Still, it’s better than no thermometer.

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From NPR and The New York Times

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