A calorie may not be a calorie

capperboy

We often read how estimating calories is an inexact science and calorie counts can be off by as much as 20% this article goes some way to explaining this.

Ref: http://www.smh.com.au/lifestyle/proof-is-in-the-eating-all-kilojoules-not-equal-20130220-2ervg.html

When it comes to weight loss, a calorie is a calorie; a kilojoule is a kilojoule. That has been the mantra of nutritionists, dietitians, and food regulators for more than a century. But when it comes to comparing raw food with cooked food, or beans with breakfast cereals, that thinking may be incorrect. That is the consensus of a panel of researchers in Boston who list the many ways the maths doesn't always add up correctly on food labels.
In a wide-ranging discussion of how food is digested in everything from humans to rats to pythons, the panel reviewed a new spate of studies showing foods were processed differently as they moved from our gullet to our guts and beyond. They agreed net caloric counts for many foods were flawed because they did not take into account the energy used to digest food; the bite oral and gut bacteria took out of various foods; or the properties of different foods themselves that sped up or slowed down their journey through the intestines, such as whether they were cooked or resistant to digestion.

The process used to estimate calories for food was developed at the turn of the 20th century by Wilbur Atwater. It was a simple system of calculating four calories for each gram of protein, nine calories for each gram of fat, and four calories for each gram of carbohydrate (modified later by others to add two calories for a gram of fibre).
One key area where the system is inaccurate, Wrangham reports, is in estimating the calories for cooked food. Cooked items often are listed as having more calories than raw items, yet the process of cooking meat gelatinises the collagen protein in meat, making it easier to chew and digest - so it takes fewer calories to eat. Heat also denatures the proteins in vegetables such as sweet potatoes, says Harvard University evolutionary biologist Rachel Carmody, who studies the energetics of digestion.

The way foods are processed can also make them easier to digest. Take ''resistant'' starch in cereal kernels, such as barley grain, or beans, which take a long time to digest. Grind the same cereals into flour or process it into breakfast cereal or instant oatmeal, and it becomes easy to digest, says biochemist nutritionist Klaus Englyst of Englyst Carbohydrates, a carbohydrate chemistry firm in Southampton, in Britain. This is why ''bread is more rapidly digested; beans more slowly,'' he says.


Conclusion

''But why are you doing this? Will it make a real difference? If you want to lose weight, you still have to cut back on calories.''

Lupercalia

Yeah, I've read similar articles recently as well. I also saw a great little video made by a NYC filmmaker about the mislabeling of nutritional info on the backs of packaging. That's a different issue, but somewhat related, I suppose.

Most of the measurements we use to help us lose weight are pretty imprecise--calorie counts, estimates of our BMRs, calories burned via HRMs, the display on a cardio machine, or a calculator here on MFP...none of it is super accurate. Most people don't have DEXA scans to tell them their lean body mass, body fat percentage, BMR, all that stuff, so once again, we are living in a world of estimation. I'm thinking even DEXA can't be 100% accurate. I think it's the most accurate way to monitor body composition there is, but even at that there is still a margin of error.

neanderthin

Lots of variables for sure, but digestion regardless of time is accounted for on the outside of the EBE. I'm sure we'll continue to learn more about nutrition and digestion going forward, but it will never circumvent cals in vs out.

elephant_in_the_room

Of course a calorie is not a calorie. Well it is, but not as far as your body goes, obviously.

A calorie is the energy needed to increase the temperature of 1 gram of water by 1 kelvin at standard atmospheric pressure.
And what we count as calories when we talk food are usually kilocalories.

Coal has a relatively high calorific value, but I wouldn't recommend to eat it, and if you did, it's calories would probably do very little for your body.

This came up when we discussed calories in a Big Mac today.... "what's in a Big Mac?" "-Plastic." - "Plastic doesn't have any calories." - "oh but in fact, it does...."

quirkytizzy

Of course a calorie is not a calorie. Well it is, but not as far as your body goes, obviously.

A calorie is the energy needed to increase the temperature of 1 gram of water by 1 kelvin at standard atmospheric pressure.
And what we count as calories when we talk food are usually kilocalories.

Ha we just covered this is Science class this week. The formulas made me want to tear out my hair. I still cannot figure out how it relates to the fact that putting away 2 Big Macs a day shot up my weight.

bryanf101

@capperboy : Conclusion is quite amazing... hahahaha