This sentence is a proverb. In the past 50' s and 60' s, there were many children in every family. They were all poor and they could eat well. Fat people are a symbol of family wealth. In particular, there is a fat hostess at home, which is often used to describe Wang Jia Wang Fu.
On the contrary, today, fat people have become synonymous with diseases. Whether fat or thin, good health is a blessing, but also a house.