Nutritional panels are notoriously inaccurate. One reason the information displayed cannot be trusted is because compliance is lax. The FDA permits a 20% margin of error in labeling – for example, a nutrition label that says 200 calories may actually contain anywhere from 160 to 240 calories and still be FDA-compliant1
But the real reason to stop trusting nutritional panels is that the information they present is inherently misleading. Nutritional panels use an outdated system devised in the 19th century that treats different foods as if they’re the same: 9 calories for every gram of fat, 4 calories for every gram of carbohydrates, and 4 calories for every gram of protein. 2
But all foods are not equal. 3 Not only is a gram of carrots not the same as a gram of potatoes, but a cooked potato is not the same as a raw potato because cooked foods generally provide more calories than raw food. 18 Scientific studies back this up - studies on mice show that eating raw sweet potatoes results in weight loss, while eating cooked sweet potatoes results in weight gain. Similarly, eating cooked meat causes greater weight gain than eating raw meat. 2
Cooking foods breaks them down, making them easier to digest. The more a food is cooked and processed, the more calories it’s likely to provide. And foods more difficult enough to digest (like nuts) don’t release all of their calories. Even the type of bacteria in your gut affects how many calories and nutrients you absorb. 2
And the most important the thing to know about any food is never included on any nutritional panel:
How much will your body actually absorb?
1. US Food and Drug Administration. Guidance for Industry: Nutrition Labeling Manual - A Guide for Developing and Using Data Bases. 2014. Available at: http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm063113.htm. Accessed December 18, 2014.
2. Dunn R. Science Reveals Why Calorie Counts Are All Wrong. Scientific American. 2013;(Volume 309, Issue 3).
3. Martinez J, Navas-Carretero S, Saris W, Astrup A. Personalized weight loss strategies – the role of macronutrient distribution. Nat Rev Endocrinol. 2014;10(12):749-760. doi:10.1038/nrendo.2014.175.