As I stated in the introduction to this chapter, the Rambam's fourth chapter is devoted almost entirely to health issues. As we saw earlier, the Ramban views maintaining one's health as a religious obligation; accordingly, he devoted a chapter of his work to medical advice. Although a fair measure of his advice is archaic, I decided for completeness' sake to translate this chapter in its entirety, offering virtually no comments of my own.
 There are foods which are particularly unhealthful, which one should never eat -- such as large, old, salted fish, old salted cheese, mushrooms, old salted meat, grape juice (lit., "wine from its vat"), and a cooked dish which was left out so long it emits its odor. The same is true of any food which is foul smelling or exceedingly bitter. Such are as poison (lit., "a drug of death") to the body.
There are other foods which are harmful but not as bad as the first ones. Therefore, a person should eat them only in small quantities and on rare intervals (lit., "after many days"). He should [also] not accustom himself to making his meal of them or regularly eating them together with his meal. [These are foods] such as large fish, cheese, milk 24 hours after it was milked, meat of large oxen and large he-goats, beans ("pul"), lentils, "safir" (Jastrow: a species of bean), barley bread, matzah, cabbage, leek, onions, garlic, mustard, and radishes. All these foods are harmful. It is not appropriate for one to eat them except in very small amounts during the rainy season. But outside of the rainy season one should not eat them at all. Beans and lentils alone one should eat neither in summer nor in the rainy season. Gourds / pumpkins ("delu'in") one should eat a little of in the summer.
 There are [other] foods which are harmful but not as much as the [above]. They are: waterfowl, small doves, dates, bread roasted in or kneaded with oil, flour sifted so finely it does not even have a hint (lit., "scent") of bran, fish brine, and pickled fish-hash ("moris"). One should not eat such foods excessively. A person who is wise, who subdues his evil inclination, and who is not drawn after his desires, and who [as a result] does not eat any of the aforementioned foods at all (except for medical reasons) is considered strong.
 One should refrain from [eating] tree fruits. He should not eat too many of them, even dried and certainly fresh. Before they ripen entirely they are as swords to the body. So too, carobs are always harmful. All sour fruit are harmful. One should eat only a bit of them in the summer and in hot climates. Figs, grapes and almonds are always beneficial, both fresh and dry. One may eat of them as much as he wants (lit., "all his need"). Nevertheless, one should not eat them constantly even though they are the best of all tree fruits.
 Honey and wine are bad for children and good for the elderly, certainly in the rainy season.
One should eat in the summer two thirds of what he eats during the rainy season.
 One should always attempt to have his bowels loose, a little bit close to diarrhea. An important principle in medicine is that whenever a person does not have a bowel movement or does so only with difficulty, many sicknesses result.
How should one loosen his stomach if it has become a little tight? If he is young, he should eat every morning salted, spiced, boiled vegetables with oil, fish brine and salt and without bread. Alternatively, he should drink the broth of cooked beets or cabbage together with oil, salt and fish brine. An older person should drink honey mixed with warm water in the morning. He should then wait about four hours and eat his meal. He should do this day after day for three or four days if needed until his bowels loosen.
 Another principle is stated regarding the body's health. Whenever a person works and exerts himself greatly when he is not full and his stomach is loose (i.e., not constipated), he will not get sick and his strength will increase -- even if he [previously] ate unhealthy foods.
 [Conversely], anyone who relaxes (lit., "who sits securely") and does not exert himself or someone who delays going to the bathroom or who is constipated, even if he eats healthy food and takes care of his health, all his days will be with aches and his strength will diminish.
Excessive overeating (lit., "heavy eating") is as poison to a person's entire body. This is a basic principle regarding all illnesses.
Most illnesses which afflict people are only the result of unhealthy food or because a person fills his stomach and excessively overeats -- even healthy foods. This is as Solomon said in his wisdom, "[One who] guards his mouth and tongue saves his soul from affliction" (Proverbs 21:23). Namely, [this refers to] one who guards his mouth from eating unhealthy foods or from [over-]satiation, and his tongue from speaking [matters] other than his needs.
 The way to bathe is that a person enter the bathhouse every seven days. He should not enter shortly after eating nor when he is hungry but rather when his food begins to be digested. He should wash his entire body with hot water [but] not so hot that it burns the body. He should wash his head alone with water which does burn the body. Afterwards, he should wash his body with warm water, then with [progressively] cooler water until he washes with cold water. On his head, he should not use warm or cool water at all.
One should not wash in cold water in the rainy season. He should not wash until he sweats and wears out (lit., "crushes") his entire body. One should not spend too long in the bathhouse, rather after he sweats and wears out his body, he should rinse off and leave.
One should check if he needs the bathroom both before entering the bathhouse and after leaving it. He should likewise check himself regularly both before and after eating. Likewise both before and after having relations, before and after exerting oneself, and before and after going to sleep -- in total ten times.
 When a person leaves the bathhouse he should dress and cover his head in the outer room so that he won't be affected by cold air (lit., "the cold wind will not prevail over him"). Even in the summer one must be careful [in this regard].
One should wait after leaving until his soul is restored, his body is rested, and the heat has left him. He should then eat. If he sleeps a little upon exiting the bathhouse before eating it is exceptionally good. One should not drink cold water upon exiting the bathhouse, and it goes without saying that he shouldn't drink in the bathhouse. If one is thirsty when he departs and cannot wait (lit., "cannot restrain himself"), he should mix water with wine or honey and drink.
If one anoints [himself] with oil in the bathhouse during the rainy season after rinsing himself off it is good.