Does cooking affect the calories in food?

[DSeid]

Mostly cooking makes it easier to absorb the calories.

… cooking also altered the meat itself. It breaks up the long protein chains, and that makes them easier for stomach enzymes to digest. “The second thing is very clear,” Wrangham adds, “and that is the muscle, which is made of protein, is wrapped up like a sausage in a skin, and the skin is collagen, connective tissue. And that collagen is very hard to digest. But if you heat it, it turns to jelly.”

As for starchy foods like turnips, cooking gelatinizes the tough starch granules and makes them easier to digest too. Even just softening food — which cooking does — makes it more digestible. In the end, you get more energy out of the food. …

[Surreal]

DSeid is correct, cooking food makes food softer and therefore easier to digest, so post-prandial thermogenesis is reduced and you gain more weight than you would from uncooked food.

In fact, in one experiment the simple act of grinding up rat pellets to make them softer produced significant weight gain in rats as compared to controls, even though their diet was calorically identical:

http://jdr.sagepub.com/content/82/6/491.full.pdf

So the oft-repeated notion that “all Calories are the same” has been thoroughly disproven.

[Ferret_Herder]

@Strassia

Assuming the sugar is converted only to alcohol (which would make it useless in bread), cooking would cause the alcohol to evaporate.

Only some of it. There would be a loss, but alcohol does not completely evaporate in cooking. Extract from USDA Table of Nutrient Retention - anywhere from 85% of alcohol (added to boiling liquid, then removed from heat) to 5% (stirred into mixture then baked or simmered for 2.5 hours) can remain.

[Surreal]

@Strassia

Conversely, some proteins have the opposite affect. Hard boiled eggs take more energy to digest than raw or soft cooked eggs.

Raw eggs are only partially digested:

http://ajpgi.physiology.org/content/277/5/G935.full

Amounts of 5.73% and 35.10% (P < 0.005) of cooked and raw test meal, respectively, escaped digestion and absorption in the small intestine. A significantly higher percentage of the malabsorbed raw egg protein was recovered in urine as fermentation metabolites.

[Silene]

Hi there,
what about sugar…? How come when I bake a cake, the dough tastes sweeter than when the cake is ready after 40 minutes. If I try it after 30 minutes, the wet parts in the cake taste much sweeter than the dry parts. How come? And would thy have the same amount of calories?

[dracoi]

@Silene

Hi there,
what about sugar…? How come when I bake a cake, the dough tastes sweeter than when the cake is ready after 40 minutes. If I try it after 30 minutes, the wet parts in the cake taste much sweeter than the dry parts. How come? And would thy have the same amount of calories?

Sugar is sensed by your taste buds only when it is dissolved. It makes sense that an already liquid cake batter would be more easily dissolved than a cooked batter, and that wetter parts of cake would dissolve more easily than dry portions.

There wouldn’t be any difference in calories, though. By the time you caused a measurable change in calories, you’d be turning the cake into charcoal.