Calories - cooked vs raw

Mass has nothing to do with calorie estimates, nor does water. In order to understand how calories are measured in food, you must understand how the calories are translated to energy requirements and usage by your cells how it relates to food breakdown in your body (metabolism). It would be good to have some understanding of the thermodynamics of metabolic processes in your system, but that could be simplified also - so that at least one could understand what it means when they consume calories in food and the effects of cooking.

When food is cooked, such as meat, the single units of amino acids in proteins unfold such that their side chains become more easily available for attack by our digestive enzymes, yielding more energy for your body (hence, higher calories). The structural components in raw foods require further steps in the metabolic pathway of your cells (and sometimes more, and different enzymes from different pathways to catalyze the reaction of breaking down the food --> uses even more energy; burning calories), and thus require a greater amount of energy FROM your body to do so (lowers the net calories that you will receive from that food - a good thing if you're trying to lose weight). Thus, the process of breaking down whole foods requires more complex pathways (think of the difference in breaking down simple vs. complex sugars). More complex = better. Another example would the processes involved when you eat celery - which are known to provide "negative calories". The energy that is used by your body to breakdown the components of celery is greater than the calories that is provided by celery itself. Hence, you get a net calorie that is negative (you burned more calories eating celery than you consumed calories).

This is why highly processed foods are higher in calories. When referring to "processed" foods, it means that the compound units of the food, in its native form (whole steak) has been broken down numerous times in various ways (heat, chemical processing for extending meat preservation, physical breakdown such as grounding or blending, etc.). The result, for instance, will be a piece of ham, or a hotdog. These processed foods provide more energy for your body as their individual chemical units have been broken down so much that when you consume the food, your body's digestive enzymes are capable of breaking down the food by converting it to energy, VERY quickly. The steak, in contrast, will be a much longer process as it will involve more pathways and a higher concentration of the digestive enzymes to break it down to single units for conversion to energy - resulting in lower net calories that you will receive from that food because your body used up energy in process. The breakdown of food QUICKLY is not a good thing if your body does not eventually USE (via exercise, or whatever) up any calories you consumed in excess. Candy, for instance, the sugar molecules that you consumed in excess will eventually be converted to triglycerides (your fat storage molecules) to store in your adipose tissue (your fat cells) for long-term energy storage.

Please understand that the measure of calories is not related to mass/weight of food. Because even then, increases/decreases in mass due to water has no effect on energy in your body; it would otherwise make you feel dehydrated vs. hydrated. It might only have an affect on energy in that it affects the solubility and equilibrium of essential minerals in and out of your cells - which, have nothing to do with energy. Calories in food is a measure of energy that can be consumed by your body.


If you want more information, here is a good start:
http://blogs.discovermagazine.com/crux/2011/12/08/why-calorie-counts-are-wrong-cooked-food-provides-a-lot-more-energy/#.U9WDWqg4f-k

There are studies that focus on these topics. Cheers.

Yeah. No.

Reported calories in foods are not determined based on biological usage. They are determined by being burned in a calorimeter and are reported as a function of mass (cals per g, for example), which is why mass matters and explains all of the differences in reporting in cooked vs raw except where something happens like fat rendering out of meat.

Quick made up examples:

100g potato, raw -> 50g potato, baked (50g water lost to steam, total calories the same, calories per g doubled)
100g pasta, raw -> 200g pasta, cooked (100g water absorbed, total calories the same, calories per g halved)

Sorry - another note.

Reported calorie estimates are NOT a *representative* of biological usage. Not a true one, at least. There is an error rate that varies of up to about 20% (sources, sources, sources)! However, they are in fact BASED on biological usage (what was the purpose of estimating energy intake from food in the first place, then?). The usage of the bomb calorimeter (plus some further experimental steps) is an over-simplified attempt to MIMIC biological systems in order to attain caloric measurement values that serve as useful information about food energy availability to human BODIES.

Article --> http://www.fishersci.com/ecomm/servlet/cmstatic?href=Scientific/researchAnalytical/ProductsServices/Food_Diagnostics/food_beverage_newsletter_bombcal.jsp&store=Scientific&storeId=10652

The measurement simply does not stop at the process of burning organic content in a vessel. Lol.