I don't see that a chaste person equates to one who eats in moderation.
Sexual intercourse is reserved by nature for a lifelong, exclusive, male/female relationship for the begetting and raising of children, and the mutual care of the spouses. This is intuitively obvious and proven by common experience. Therefore, those who reserve intercourse for marriage are happier than those who don't; just as those who eat as nature intends (in moderation, primarily for nutrition and growth) are happier than those who abuse food (who overeat, eating primarily for pleasure).