A Calorie REALLY ISN'T a Calorie

Now I want BBQ. Thanks a lot.

We absorb more of the calories in "processed" foods (not just packaged foods, anything cooked, pureed, etc.), especially carbs. We burn off 20% of the calories in protein just digesting it. So it turns out that whole clean eating/whole foods thing has some truth to it. 2,000 calories of Twinkies delivers more calories to your body than 2,000 calories of vegetables and meat. I'm still gonna have a slice of cherry pie tonight though.

http://www.livescience.com/26799-calorie-counts-inaccurate.html

Highlights:

For the most part, the inaccuracies are small, but some foods may have actual caloric values that differ from the estimated values by as much as 50 percent, experts say

Calories in processed foods are likely close to the values that the Atwater system estimates. For example, if you eat a mashed potato that's been calculated by the Atwater system to contain 300 calories, you're likely getting most of those calories, Carmody said. But if you eat a whole, unprocessed potato of the same size, you'll take in around 200 calories, she said.

When we digest food, we also give off energy as heat. The amount of heat we radiate depends upon the exact components of the food. For proteins, it's about 20 to 30 percent of the food's calories — so if we eat 100 calories worth of protein, we get about 80 calories from it, Carmody said. For fats, it's much less, about 0 to 3 percent, she said. (So if we eat 100 calories worth of fat, we'd get 97 of those calories.)

For example, the almond study, which also accounted for calories lost in feces, suggested that some of the fat in whole almonds is locked away in a structure our bodies can't digest. While the Atwater system says a serving of whole almonds has about 170 calories, the almond study found it actually has about 130.

So, perhaps that's a better way to look at the problem: labels wouldn't be so misleading if we thought of their Kcal listings not as total Kcals, but as max Kcals you could get from any given food. And, if one is to determine some kind of main takeaway dietary message from all this discussion, it may be simply this: that by eating more whole, raw foods (like other animals and like our pre-human ancestors did), you can count on fewer Kcals (thank your microbes for halving the amounts of Kcals you absorb once food reaches your intestine); and you can count on greater digestive and metabolic costs by eating well-balanced meals containing plenty of fiber and protein per meal (think "python diet").