To eat on the Sabbath the same amount of food eaten on a working day is entirely out of place. The Sabbath is the day set apart for the worship of God, and on it we are to be specially careful in regard to our diet. A clogged stomach means a clogged brain. Too often so large an amount of food is eaten on the Sabbath that the mind is rendered dull and stupid, incapable of appreciating spiritual things. The habits of eating have much to do with the many dull religious exercises of the Sabbath. The diet for the Sabbath should be selected with reference to the duties of the day on which the purest, holiest service is to be offered to God. CH 577.3
Eating has much to do with religion. The spiritual experience is greatly affected by the way in which the stomach is treated. Eating and drinking in accordance with the laws of health promote virtuous actions. But if the stomach is abused by habits that have no foundation in nature, Satan takes advantage of the wrong that has been done and uses the stomach as an enemy of righteousness, creating a disturbance which affects the entire being. Sacred things are not appreciated. Spiritual zeal diminishes. Peace of mind is lost. There is dissension, strife, and discord. Impatient words are spoken and unkind deeds are done; dishonest practices are followed and anger is manifested—and all because the nerves of the brain are disturbed by the abuse heaped on the stomach. CH 577.4
What a pity it is that often, when the greatest self-denial should be exercised, the stomach is crowded with a mass of unhealthful food, which lies there to decompose. The affliction of the stomach afflicts the brain. The imprudent eater does not realize that he is disqualifying himself for giving wise counsel, disqualifying himself for laying plans for the best advancement of the work of God. But this is so. He cannot discern spiritual things, and in council meetings, when he should say Yea, he says Nay. He makes propositions that are wide of the mark, because the food he has eaten has benumbed his brain power. CH 578.1