Calories - cooked vs raw

I have no clue but always have been interested! So bumpy bump.

Why is there a calorie difference between raw and cooked foods?

The difference is mainly due to water loss or gain. Cooking methods like baking, grilling and roasting will cause a food to lose water compared to say steaming and boiling. In fact boiling may cause the food to gain weight – as in the case of rice and pasta.

When a food loses water it will become lighter in weight and more calorie dense - so the cooked food will contain more calories than the raw when comparing weight for weight. An example being a jacket potato. As the potato loses water during baking, it becomes more calorie dense - which is why when comparing weight for weight, a jacket potato contains more calories than boiled.

On the other hand, if a food absorbs water, the calories will be lower compared to the same weight raw - because the food has become less calorie dense. This is true of rice and pasta.

In most cases, it is probably easiest to weigh the raw food and use these figures. If you then cook the item and add any extra ingredients such as sugar or oil, you need to measure and enter these ingredients separately e.g. if you fried your mushrooms in oil or stewed apples with added sugar.

In summary, it doesn't really matter which figure you use - as long as the weighed state of your product (raw or cooked) matches the description in our database

bump

The calorie difference comes from the fact that when you consume food, the compounds that make up X (food in question, i.e., meat, vegetables, whatever it might be) require your body's digestive system to "do work" in order to break down the single units of X (the units need to be converted to ATP - energy for your cells) so that the compounds of food can be available to your body in the form of ENERGY (measured in units of calories in food).

The application of HEAT when cooking will accelerate the breakdown of the compounds of X, leaving less work required by the body to break down the food. Eating food COOKED thus can be seen as having more energy available for usage by your cells, sooner, for LESS WORK done by the body (your cells' machinery for metabolizing food).

The number of calories when eating X raw will be lower than when eaten cooked because your body has to USE ENERGY that already exists in the body (glucose, amino acids from protein, or fatty acids in your fat storage cells) in order to CONSUME ENERGY (break down the structural components of the food for consumption by your individual cells) from eating X. When eating that same food cooked, your body has to *do less work* (USES LESS ENERGY) to digest and metabolize the food, while consuming EQUAL ENERGY.

Bit of mathematical proof:
Calories in X, eaten cooked: 115 cal
Calories in X, eaten raw: 100 cal (15 calories used when eaten raw because the body had to do more work to break down the food)




- Biochemistry BSc

The calorie difference comes from the fact that when food is raw, the compounds that make up X (food in question, i.e., meat, vegetables, whatever it might be) require your body's digestive system to "do work" in order to break down the single units of X (the units need to be converted to ATP - energy for your cells) so that the compounds of food can be available to your body in the form of ENERGY (measured in units of calories in food).

The number of calories when eating X raw will be lower than when eaten cooked because your body has to USE ENERGY that already exists in the body (glucose, amino acids from protein, or fatty acids in your fat storage cells) in order to CONSUME ENERGY (break down the structural components of the food for consumption by your individual cells) from eating X. When eating that same food cooked, your body has to *do less work* (USES LESS ENERGY) to digest and metabolize the food, while consuming EQUAL ENERGY.

The application of HEAT when cooking will accelerate the breakdown of the compounds of X, leaving less work required by the body to break down the food. Eating food COOKED thus is having more energy available for usage by your cells, sooner, for LESS WORK done by the body (your cells' machinery for metabolizing food).


- Biochemistry BSc

This makes zero sense.

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.

The reason for potatoes might be because of the resistant starch (RS). When you cook them they lose a lot of their RS. If you cook them and then cool them they actually gain more RS.

Resistant starch (RS) is starch and starch degradation products that escape from digestion in the small intestine of healthy individuals.[1] Resistant starch is considered the third type of dietary fiber, as it can deliver some of the benefits of insoluble fiber and some of the benefits of soluble fiber.

http://en.wikipedia.org/wiki/Resistant_starch

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)