Our source of carbohydrates is plants. Plants compose carbohydrates in two forms:
A- Storage carbohydrates which are :
1- Easily digested to release glucose quickly.
2- Of compact size for space economy of the plant.
3- Of spacial configuration that is compatible with Amylases (starch digesting
Starch represents this group of storage carbohydrates.
B- Structural carbohydrates which are :
1- Of large intra-molecular spaces to hold water inside the plant.
2- Not liable to digestion by carbohydrate digesting enzymes to guard against decay of living plants.
3- Of rigid nature for stature of plants ( they have no bones).
Cellulose & Hemicellulose represent structural carbohydrate group.
When humans eat digestible carbohydrates (starchy food), their digestion starts as soon as they are admixed with saliva where its amylase splits starch into linear fragments that is ended with formation of soluble glucose which is absorbed through the intestine.
When they eat indigestible carbohydrates (fibers), the later acquire volume and weight all the way till excreted almost undigested and unchanged acquiring the consistency of sponge.
When we compare the digestive trip of starch and fibers, we find that starch is disappeared from the digestive tract easily to appear in the blood in the form of glucose ,i.e. easily earned large amount of calories, while fibers (cellulose) gets heavier along the whole trip and the digestive tract works harder to push down the water saturated fibers while extracting a small amount of calories present in digestible materials adhered to fibers, i.e. the body pays calories to get rid of fibers.
Imagine immersing 2 similar pieces of sugar and sponge in water for a while, the sugar will disappear and the sponge will be saturated with water needing extra work to be moved off its place. This is what exactly happens upon eating starch and fibers, the starch is represented with sugar and the fibers represented with sponge in our example.
If you consume a digestible carbohydrate (bread, pasta, rice, desserts..etc) of 400 calories and this carbohydrate requires 150 calories to digest then you gain 250 calories that if not consumed, it would be stored as fats.
But if you consume 100 grams of-sponge- vegetables that have 25 calories and need 80 calories to digest, then you'll lose 55 grams after excreting it.
Structural carbohydrates (cellulose) form the skeleton of any vegetable or fruit and it is the digestible carbohydrates amount that determines the appreciation of a plant to be of a high negative calorie value.
There are up to 100 plants which contain a plenty of indigestible carbohydrates and minimal digestible carbohydrates. Some of these plants are:
Fibers also form fecal bulk that guard against possibility of serious constipation that results from consumption of diets containing much of white flour and meat.
You can choose your list of preferred negative calorie food to fight overweight.
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