Почему нельзя сильно утеплять новорожденного ребенка?

In the room where Mr Small. Dr Foam and Mrs Bulmer were talking to the children, there were some really old people. Mr Small went up to one of them. He said he saw that he was a very old man.
The old man replied he was 90.
Mr Small asked if the old man could give the children there some advice about a balanced diet and a healthy lifestyle.
The old man said to follow his example. Not to smoke,not to drink, not to eat too much sugar or fat and drink lots of water.
At that moment Dr Foam found another old man who looked older than the first one. He was sitting in a wheelchair, but his eyes were merry and bright.
Dr Foam asked how old he was.
The man replied that he was ninety-five.
Doctor Foam asked if the old man could tell them why he had lived so long.
He answered that it was easy. He did dexercises, and he didn't smoke or drink. He spent a lot of time in the open air and he was a vegetarian.