If you're diligently logging your daily calories to lose weight, be wary. Nutrition experts say current calorie counts on healthy foods could be incorrect

By Charlotte Hilton Andersen
April 29, 2015
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If you've ever wondered why counting calories feels so hard, it might be because those numbers on the nutrition label aren't even correct. According to an independent assessment, calorie counts listed on nutritional labels are flawed, with some overestimating calories by up to 25 percent! (That probably makes you wonder: Are You Counting Calories Wrong?)

Junk food and processed snack nutrition labels are fairly accurate, according to the experts, but foods high in protein and fiber-some of the healthiest foods you can eat!-are the ones most affected by the inaccuracy. Take everyone's favorite afternoon snack: nuts. One serving of almonds is listed at 160 calories, but, in reality, scientists say that amount only adds up to around 120 calories. Good news for anyone who's ever overindulged in nuts (it's so easy to do!), but bad news for anyone on a low-carb diet or those using calorie counting as a way to manage their weight.

The discrepancies occur because there is a difference between usable calories, or the energy your body actually gains from the food, and total calories, says Peter LePort, M.D., medical director of MemorialCare Center for Obesity in California. Something called the Atwater system has been used to calculate the caloric value of foods for decades. It's a process that burns the food and then measures the amount of energy it takes to heat up one gram of water one degree Celsius. But it's not an accurate representation of what happens in the human body, LePort says. That's because proteins and fibers are not completely digested, so we excrete some of the calories. So the more protein and fiber a food has, the more inaccurate the calorie counts.

This is one reason why more and more experts are discounting calorie-counting as a primary method of weight management. (It's a big debate! Should You Count Calories to Lose Weight?) "I wouldn't throw the entire calorie counting system under the bus," explains Wendy Bazilian, R.D., author of The SuperFoodsRx Diet and co-owner of Bazilian's Health Clinic in San Diego, CA. "But when choosing food, I always advise looking first and foremost at the ingredient list. After determining the quality of the food, you can look at the nutrient fact panel for certain particulars like sodium, relative fiber value, and the balance of macronutrients. Only after all of that would I say to look at calories."

LePort agrees, saying the true value of this latest discovery about calorie inaccuracy is to remind people that, in the end, calorie counts are always just an approximation. "An approximate calorie count is all you really need to know. After that, your body will tell you what it needs. People need to be focused on eating healthy, whole foods and listening to their body about when they are hungry rather than relying on some number."