What is the English proverb equivalent of 腹八分目{はらはちぶんめ}に[医者]{いしゃ}いらず and the history behind the proverb?


[![enter image description
here](https://i.stack.imgur.com/fF79Q.jpg)](https://i.stack.imgur.com/fF79Q.jpg)

**Context:**

I encountered this in a compulsory book about moral education for elementary
school student by MEXT "私たちの道徳"
[Source](http://www.mext.go.jp/a_menu/shotou/doutoku/detail/1344255.htm)

My question:

>   1. What is the best equivalent proverb in English of: **腹八分目に医者いらず**?
>
>   2. What is the **background story** of this proverb in Japanese?
>
>   3. Why do the Japanese use " **八分目** " or " **80% full** "?
>
>   4. Is there probably any **medical record** or any **medical publication**
> source that this is true or is this only a conjecture at best?
>
>

My attempt in translating it:

> **Eating in moderation is good for your health**.
>
> **An apple a day keeps the doctor away**.

Is this natural?

Thank you in advance!




>   1. What is the best equivalent proverb in English of: 腹八分目に医者いらず?
>

I'm not really good at English proverbs, so I'll leave this to someone else.
Basically the meaning of this proverb is something very simple,
straightforward and mundane, "Don't eat too much." Nothing more or less. Of
course 医者いらず is an exaggerated expression, and it should be taken as "～ is
good for your health."

>   2. What is the background story of this proverb in Japanese?
>   3. Why do the Japanese use "八分目" or "80% full"?
>   4. Is there probably any medical record or any medical publication source
> that this is true or is this only a conjecture at best?
>

I'm afraid to say this, but there is not much to talk about regarding this
saying. This saying is fairly old, and obviously not based on an evidence from
modern scientific research. I believe someone in the old days chose 80% either
purely empirically or arbitrarily. The number "8" is not very important.

Some expressions like 矛盾 have fascinating background stories, but 腹八分目 is a
pretty simple and straightforward Japanese phrase which has nothing to do with
metaphor, philosophy or religion. I think it's extremely difficult to trace
who first said this. After all, it can be said that the idea of "eating too
much is bad for your health" itself is almost as old as the history of human
civilizations.

