Aside from large-scale physical changes (e.g., fats burning off or remaining in a pan), do the total calories in a food’s ingredients equal the total calories of the finished product? That is, if I add up the calories of all ingredients going into a bread, will the calories in the baked loaf be equal to that number? Or can the cooking process result in lower calories (e.g., chemical reactions using up some of the energy in the ingredients) or higher calories (e.g., combined ingredients absorb heat energy in undergoing their reactions)? Oh, this isn’t related to dieting, so even small changes are interesting.
Well, there is the matter of starches converting to complex carbohydrates that can be absorbed- as in oatmeal.
Not sure I understand. Are you saying that the calories listed on a box of oatmeal are X, but that after cooking some starches convert to complex carbohydrates so that the final, cooked product contains X + Y calories?
For all practical purposes, the calories in ingredients equal the calories in cooked or prepared foods.
Sure, for all practical purposes. But this is the Dope! Who’s practical? I, too, am curious what the answer is on a purely technical level.
Starch IS a complex carbohydrate that can be absorbed by the body. 
Assuming the cooking does not actually burn anything (which would of course reduce the calories), the loss of actual calories would be minor. However, if you are really trying to figure out how much energy you will extract, that is a different matter. As mentioned, complex carbohydrate structures can simplify when cooking. A good example is potatoes. Raw potatoes and cooked potatoes have the same number of theoretical calories, but your body does not process them efficiently. The more complex forms in the raw potato take considerable energy for your body to transform into a usable form. Similarly, your body cannot process some forms at all, such as fiber. Fiber has calories in the sense that if you burn it will release heat, but they are all still present when it leaves the body.
Conversely, some proteins have the opposite affect. Hard boiled eggs take more energy to digest than raw or soft cooked eggs.
I read once that you would starve to death on a diet of raw potatoes, raw celery, and hard boiled eggs.
I wouldn’t be surprised if hard boiled eggs are not as easily digested as raw or soft eggs, but they’re still easy to digest overall, no?
Not the best cite, but this pamphlet on HIV and diarrhea says the following:
If you’re getting into theoretical but tiny-to-the-point-of-immeasurable differences, then heating things will drive off volatile compounds, most of which presumably contain some calories.
And anything with yeast (bread, beer) will have less energy after the yeast get through digesting carbohydrates to alcohol. That might actually be measurable, but I don’t have any numbers.
I don’t believe this for a second.
Almost by definition, this is not true. Volatile chemicals are not carbs, fats, or proteins and so can’t have calories. If you’re saying that carbs, fats and proteins are broken down to create byproducts that include volatile chemicals, well, maybe, possibly, but I’d have to see the chemistry.
Alcohol has 7 calories per gram while carbs have 4 calories per gram. I’m not sure how this breaks out in actual food products.
At an extreme, if you cook food to charcoal, the carbon doesn’t provide any calories. I’m sure cooking produces other complex compounds that can’t be digested.
This is interesting in that it helps with an understanding of what a calorie is (beyond a line in a book or Web site).
Let me back wayyyyy up for a moment. You have some dirt. I’m assuming dirt has no calories. You have some water. You have a sugar beet seed, which has minimal calories. You put them all together and add a lot of energy via sunlight, and eventually you have a something with a much higher calorie content than when you started.
Now, that’s clearly a different situation and marginally related at best. But it contains the seed (heh) of the question.
I have several ingredients for bread. Flour, water, etc. The question of more calories occurred to me because the flour is reacting/combining with the added sugars and assorted ingredients to make a different product. Could otherwise inert and calorie-free parts of the flour molecules break apart and recombine with molecules from other ingredients to form new carbs, fats or proteins? Could the heat energy from the oven be transferred/absorbed/get locked up in the physical structure of the bread?
What about cooking something that is non-digestible in its whole form (a grain?) that becomes digestible when the outer cover is cracked and the fats & proteins inside are released?
All the carbon and oxygen are coming from the air. You forgot that.
Remember that also, by definition, you simply cannot create more food energy by eating something. Since the yeast is fermenting the carb, chopping a chemical bond, extracting its energy and essentially pooping out the remaining molecular pieces as alcohol, fermenting (in the culinary sense) something must reduce its caloric content.
This assumption of course is completely reversed if you use your yeast to ferment an otherwise indigestible carbohydrate.
Charring (oxidizing) your food will reduce its calories, as mentioned.
In theory I might WAG that a dry cooking method might dehydrate/denature certain proteins or carbohydrates into polymers that your body wouldn’t be able to crack.
ETA: Think about your bread-rising yeast. Those bubbles are CO2. Where do you think the carbons are coming from?
Right. And all these things are calorie-free until the sun adds energy, allowing them to combine into structures that give rise to caloric measurements. Biology is involved, of course, but I don’t know if similar calorie creation can take place in an oven with simple combinations of ingredients.
Yes, but I didn’t mean to suggest you’d wind up with more calories than you started. It’s just that if two grams of carbs wind up as one gram of alcohol the net difference is one calorie. But that’s not the same as taking away two grams of carbs and getting nothing in return, which is the situation I was responding to. I don’t know what the actual ratios are, so the final number could be almost anything.
It takes more than gram of carbs to produce a gram of alcohol, though. It’s been too long since my days in biochem, but the yeast are growing on the process, so we know that some energy from the original food has been consumed - all that CO2 that leavens bread is the result of digestion.
(And, for what it’s worth, yeast only stop digestion at alcohol under anaerobic conditions. In bread-baking, they’re mostly converting the starches fully to CO2.)
Why? Most of the carbohydrates in celery are non-soluble fiber. In potatoes, they are extremely long chain carbohydrates. In eggs (especially the whites) the proteins break down into amino acids and then rejoin into almost random polymers. The human body is extremely inefficient at extracting energy from these forms.
Here you contradict yourself. Alcohol is a volatile chemical that can be lost during cooking.
Assuming the sugar is converted only to alcohol (which would make it useless in bread), cooking would cause the alcohol to evaporate.
I have been wondering the same thing. I dont remember the science behind it from school, however I do remember tempature and time buring gave you the calories/fat content of food.
I am trying to see how, if the length of time buring a food, could reduce calories? If your buring time is in effect why wouldn’t that reduce the number of calories or fat? like grilling foods is “better” because the “fat” is not going back into the food? and blotting pizza absorbs some of the oils.
I suppose I could see the other side of it as just being a scientfic formula, but I still have a hard time accepting that, there isn’t more to it than just the formula. To me it seems flawed.
So why wouldn’t one be consuming less calories burning a steak, than a person who likes it rare?
If its about Tempature and cooking time? it only makes sense to me that it would.