Wow, I'm shocked: food labeling can be misleading. Restaurant foods measured by researchers at Tufts University had 18 percent more calories than claimed and frozen meals came in 8 percent over what was stated on the label.
Not that it concerns me, particularly. I'm dreadfully thin, probably because of my unfortunate habit of usually eating only twice a day, exacerbated by shifting my drinking habits from exuberant to moderate.
My weight gain is minimal even when I slip into a three-a-day regimen. I credit my current slogan 'everything in moderation, including moderation.'
Don't believe everything you read, caveat emptor, and similar bromides apply anyway. I do read labels, only to check relative levels of salt, glucose, sucrose and various fats. I wouldn't believe the absolute claims for a second.
Which, I suppose, makes the story a cautionary tale for those of you caught in the diet-drama of listing every food in every meal. If, like the lead researcher, you follow the package recommendations and still gain weight, try a different diet.
There is a bias in favor of under-reporting anyway, because the portion size must be as-advertised.
Also, the study used a gadget unknown to me: the dreaded 'bomb calorimeter'. It seems this nifty device is used to burn a measured sample and calculate the heat that is produced. Now, since we know that fire in your belly is just a rhetorical device, it can hardly measure what happens in your digestive tract.
Dairyscience.info has a pretty good summary in plain language. The author includes some tables showing the conversion factors for various 'food components' when they are 'burned' in our woefully inefficient furnaces.
He also offers a warning: the energy in dietary fiber can be overestimated, "there are climate, varietal and other factors that contribute towards differences in the nutrient density of fruits and vegetables" and "feeding regime, animal genetics, climate and systems of animal husbandry also affect the nutrient density of meat and milk and consequently products derived from them."
This is just a goof for me, in any case, like trying to tell whether artificial sweeteners really have two-thirds of the calories in "Carbohydrate expressed as monosaccharide equivalent."