The reason for this is the following：

1. The main difference between whole wheat steamed bread and white steamed bread is that whole wheat flour is used in whole wheat steamed bread, while white steamed bread uses flour.

2. Whole wheat flour is a product made of whole wheat by grinding and sieving (grading with appropriate particle size) and keeping the same proportion of endosperm, bran and germ as the original whole wheat. Compared with ordinary flour, it is a kind of whole wheat flour, which is only ground without the procedure of bran removal. Whole wheat flour contains all ground bran and germ. Wheat bran contains cellulose and has high nutritional value.

3. There is no β -glucosidase in human body, so cellulose can't be decomposed and utilized, but cellulose can absorb a lot of water, increase the amount of feces, promote intestinal peristalsis and accelerate the excretion of feces.

Cellulose in whole wheat flour is a dietary fiber. When eating, dietary fiber replaces the amount of some nutrients in food and reduces the total intake of food. Dietary fiber promotes the secretion of saliva and digestive juice, fills the stomach, absorbs water and swells, which can produce satiety and inhibit the desire to eat. Dietary fiber is combined with some fatty acids, so that fatty acids cannot be absorbed when passing through the digestive tract, thus reducing the absorption rate of fat.

Therefore, whole wheat steamed bread is more suitable for weight loss than white steamed bread.

Extended data

The main functions of dietary fiber are:

1, treating diabetes

Dietary fiber can improve the sensitivity of insulin receptor and improve the utilization rate of insulin; Dietary fiber can wrap the sugar in food and make it gradually absorbed, which has the function of balancing postprandial blood sugar, thus regulating the blood sugar level of diabetic patients and treating diabetes.

2. Prevention and treatment of coronary heart disease

The increase of serum cholesterol will lead to coronary heart disease. The excretion of cholesterol and cholic acid is closely related to dietary fiber. Dietary fiber can be combined with cholic acid, so that cholic acid can be excreted quickly. At the same time, the combination of dietary fiber and cholic acid will promote the conversion of cholesterol into cholic acid, thus reducing the cholesterol level.

3, antihypertensive effect

Dietary fiber can adsorb ions and exchange them with sodium ions and potassium ions in the intestine, thus reducing the proportion of sodium and potassium in blood and thus lowering blood pressure.

4, anti-cancer effect

Dietary fiber can bind cholic acid and other substances and excrete them to prevent the production of these carcinogens; Dietary fiber can promote intestinal peristalsis, increase fecal volume and shorten emptying time, thus reducing the chance of carcinogens in food contacting colon; Beneficial bacteria in the intestine can use dietary fiber to produce butyric acid, which can inhibit the growth and proliferation of tumor cells, induce tumor cells to transform into normal cells, and control the expression of oncogenes.

5. Lose weight to treat obesity

Dietary fiber replaces some nutrients in food and reduces the total intake of food. Dietary fiber promotes the secretion of saliva and digestive juice, fills the stomach, absorbs water and swells, which can produce satiety and inhibit the desire to eat. Dietary fiber is combined with some fatty acids, so that fatty acids cannot be absorbed when passing through the digestive tract, thus reducing the absorption rate of fat.

Step 6 treat constipation

Dietary fiber has strong water holding capacity, and its water absorption rate is as high as 10 times. After absorbing water, the volume of intestinal contents is increased, which makes the stool loose and soft, and it will be smoother and more labor-saving when passing through the intestine. At the same time, dietary fiber, as a foreign body in the intestine, can stimulate the contraction and peristalsis of the intestine, accelerate stool excretion, and play a role in treating constipation.

References:

Baidu Encyclopedia: Whole wheat flour? Baidu Encyclopedia: Cellulose