Last week we talked about smoking cigarettes and we explained the Halakhic principle of avoiding anything harmful to our health (see link). Technically speaking, these are not ritual-related laws (Kashrut) but they are still part of Jewish Law, specifically under the category of vensihmartem m-eod lenafshotekhem (debarim 4,15) You should 'strictly' (me-od) watch your life' (=your health).
Maimonides (1135-1206), who besides being a rabbi was also a famous physician, wrote a chapter on Health Guidelines in his Mishne Torah (hilkhot de'ot, chapter 4). He clarifies explicitly (H. 21) that the principles exposed in that chapter are pertinent for a healthy individual, not for a sick person, who obviously requires a customize diet and medical treatment.
In other words, Maimonides anticipated the modern concept of 'preventive medicine' by eight centuries. In this interesting chapter Maimonides deals with: diet, exercises, sleeping habits, sexual life , hygiene, and other practices common in his time.
A few selected illustrations of his advices on diet:
"...Maintaining a healthy and sound body is among the ways of God... one must avoid that which harms the body and accustom himself to that which is healthful and helpsthe body becomes stronger".
".. a person should not eat until his stomach is full. He should stop eating approximately at three quarters of full satisfaction"
"...overeating (akhila gasa) is like poison to anyone's body and it is the main cause of all illness".
"Don't eat unless you're hungry".
Click here to read what contemporary Rabbis say about Smoking