Reason: (1) Sweet potato is mostly starch, and it also contains vitamins, cellulose and other essential nutrients for human body, as well as rich mineral elements such as magnesium, phosphorus and calcium and linoleic acid. It is not only nutritious, but also has a remarkable weight loss effect. The reason for losing weight is that every 100g of fresh sweet potato contains only 0.2g of fat, which generates 99 kilocalories of heat energy, which is about 1/3 of that of rice. It is a good low-fat and low-calorie food, at the same time, it can effectively prevent sugar from turning into fat, which is conducive to weight loss and bodybuilding. Sweet potato contains a lot of dietary fiber, which cannot be digested and absorbed in the intestine. It can stimulate intestinal tract, enhance peristalsis, relieve constipation and detoxify, especially for senile constipation. Nutritional value of sweet potato food collocation: Sweet potato lacks protein and lipid, so it should be eaten with vegetables, fruits and protein foods to avoid nutritional imbalance. Most importantly, sweet potatoes are best eaten at the prime time of lunch. This is because after we eat sweet potatoes, the calcium contained in them needs to be absorbed in the human body for 4 to 5 hours, and the afternoon sunshine can just promote the absorption of calcium. In this case, eating sweet potatoes for lunch can completely absorb calcium before dinner, and it will not affect the absorption of calcium in other foods at dinner. (B) the nutrition and causes of carrots

① Benefiting liver and improving eyesight: Carrots contain a lot of carotene, which has the function of nourishing liver and improving eyesight and can treat night blindness;

② Promoting diaphragm and moistening intestine: Carrots contain plant fiber, which has strong water absorption and is easy to swell in the intestine. They are "filling substances" in the intestine, which can strengthen the peristalsis of the intestine, thus benefiting the diaphragm, widening the intestine, relaxing the bowels and preventing cancer.

③ Strengthening the spleen and eliminating malnutrition: Vitamin A is an essential substance for the normal growth and development of bones, which is helpful for cell proliferation and growth, is an essential factor for the growth of the body, and is of great significance for promoting the growth and development of infants.