Generally speaking, Buddhism believes that eating in the early morning will be called an eclipse, which will be better and helpful to the body at this time. At noon, they think that eating one less meal is very useful for their Buddhist health-keeping style. They also have a Zen saying that you can eat twice at a time, so these two meals are in the morning and afternoon, so you don't eat at noon.
Why are there such fat monks? First of all, Buddhism is not completely vegetarian. They also eat meat and don't break the rules. According to historical records, monks were allowed to eat wine and meat in the past. So now, for monks, one reason for gaining weight is also related to their living habits. They also add a little meat to their diet. Some monks just eat too much, and their digestive system is not particularly good, so they are more likely to gain weight. This is the difference between a fat and thin monk.
Another important reason is that they often meditate every day and do not exercise. This reason is crucial. They don't exercise, and then get up early in the morning and get hungry. And some people are the kind of people who are naturally fat, and you will get fat after drinking a mouthful of water. So, plus he doesn't exercise, the fat monk came from here.