How do the French and Japanese stay thin?

Well idk about France .

But In Japan , It's Illegal To Be Fat . Boys/Girls/Men/Woman Have A Certain Size That They Can Be .

Because French people tend to eat almost everything in the smaller portions, although many of their dishes are pretty rich in fat. When I was in Paris, I noticed that a lot restaurants, even the fast food restaurants tend to serve many dishes in smaller portions. And the French also like to drink red wine which is good for blood and heart health. French people don't rush when they are eating, they prefer to take their meal slowly while enjoying their drink or wine. Many French (especially the women) are also kind of conscious about their body looks.

Whereas the Japanese, they know how to control their eating habits. The Japanese learn to control their eating habits by following "Hara hachi bun me" (腹八分目/はらはちぶんめ) philosophy. "Hara hachi bun me" in English translation means "if you are already feel 80% full, try to stop eating." "Hara hachi bun me" (腹八分目/はらはちぶんめ) philosophy is based from the Confucian teaching about how to control the eating habits. The Japanese practice "Hara hachi bun me" (腹八分目/はらはちぶんめ) philosophy to control their eating habits so they can stay healthy. Japanese people also like to eat lean food, they don't eat much rich in fat food.

When I spent my time at France and Japan, I was really surprised with the small amount of the fat people there. Even every single French and Japanese tourists I have met are very slim (especially the women). When people describe the French and Japanese appearance, I often heard many people would often say that the French or Japanese are very slim.