If this basic rule is obeyed, there are some other things that must be done. All nutrients, including vitamins and minerals, must be included in a daily menu. Also, the ratio of nutrients must be proper, which means that most of the inserted calories must come from carbohydrates, and the rest should be from proteins and minimally from fats. This might cause some problems too, people might not have excessive weight, but can still end up with high levels of cholesterol if food rich with fat is taken.
This also means that junk or fast food should be avoided, which also might be a rule. It is not a strict rule, which means that this bad food might be taken, but only from time to time, without any exaggeration.
It is also very important to prepare a meal in the proper way. There is a difference if meat is grilled, boiled, or roasted. Also, it would be for the best to prepare the food with small amounts of additives, meaning that salt, oil, certain artificial flavors and similar things should be avoided as much as possible. This might not be easy, because most people got used to eating tasty food, which is not really possible without sauces, spices, flavors...
Oils are especially questionable and they are used in almost all food types. For example, in the United States, vegetable oils are commonly used, such as cottonseed oil. It is widely used for salads and also for pre-made food. It is cheap and lasts longer than most of the other oils, which makes it very popular. Even though it can be found in almost every house in the United States, there are some cottonseed oil dangers that people should be aware of. Some experts say that this oil might have some toxic properties (because of the presence of gossypol). Gossypol is known to create certain problems with fertility, especially in men. Furthermore, it can cause allergic issues and there are also issues that might be caused because of the fact this oil is genetically modified.