First of all, if you eat a lot, you won't gain weight. There is a problem of intake and consumption. If you consume a lot, you won't get fat. If a person does a lot of exercise in a day, such as athletes and heavy manual workers, they eat a lot but consume a lot of calories at the same time, so they won't get fat. Second, the eating habit of eating less and eating more meals, although it seems to eat a lot, is actually less likely to cause overnutrition than eating more and eating less meals. Eating less and eating more meals has less burden on the stomach, so it is a beneficial eating habit for people with bad stomach. Third, some physical reasons will also lead to eating too much but not getting fat easily, such as bad stomach and intestines, which will not be absorbed by the stomach and intestines. Nutrition is excreted with metabolism, so it won't get fat. Fourth, if the subcutaneous fat layer is not thick enough, it is not easy to store heat. This kind of people will be more afraid of cold, because the body can't store calories, so the food they eat will be converted into calories and consumed, so they won't gain weight. Fifth, although not fat is enviable, we should also be careful about the causes that may cause diseases, such as hyperthyroidism. People eat a lot, but they are thin.