How many staple foods should I eat every day if I want to have a balanced diet? Fear of cholesterol, egg yolk in the end can not eat? Recently, Wang Longde, an academician of the Chinese Academy of Engineering and president of the Chinese Society of Prevention, proposed a daily “ten tennis balls” diet at a conference. Currently a very common view, for fear of high cholesterol, and give up eating eggs, or go to the egg yolk and eat egg whites. Academician Wang Longde said, in fact, the egg yolk contains many nutrients that are very beneficial to the human body, especially lecithin. Older people are afraid of cholesterol, do not eat eggs, or eat egg whites not yolks, you will lose many essential nutrients. Cholesterol intake does not depend on the amount of cholesterol itself, but mainly on the amount of fat in the food. “Eating one egg a day does not increase the risk of coronary heart disease; if you have underlying diseases such as hyperlipidemia or diabetes, one egg for 2 days is fine.” There is also a small problem that plagues many people, whether to eat fruit before or after meals? Wang Longde academician said, eat fruit after meals when people are already full, and then eat anything including fruit, calories are over the limit. So it is recommended that we take fruit as the first course of the meal. Eating fruit before meals not only helps control calories and replenish daily essential dietary fiber, minerals and trace elements, but also allows better absorption of many auxiliary enzymes in fruits that promote human digestion and metabolism. In most reasonable dietary recommendations, it is stipulated that “how many grams of staple food and how many grams of meat per day”, but in practice, it is difficult to translate into the concept of quantity. Academician Wang Longde gave an image of daily “ten tennis balls” dietary advice, that is, daily no more than a tennis ball size of meat, equivalent to two tennis ball size of staple foods, to ensure that three tennis ball size of fruit, not less than four tennis ball size of vegetables, including the “ten tennis balls The “ten tennis balls” principle, and the “four ones” method of one egg, one pound of milk, one handful of nuts and one poker-sized piece of tofu per day.