"Wrong Conditions of Eating Food should not be eaten very hot or very cold. If food is cold, the vital force of the stomach is drawn upon in order to warm it before digestion can take place. Cold drinks are injurious for the same reason; while the free use of hot drinks is debilitating. In fact, the more liquid there is taken with the meals, the more difficult it is for the food to digest; for the liquid must be absorbed before digestion can begin. Do not eat largely of salt, avoid the use of pickles and spiced foods, eat an abundance of fruit, and the irritation that calls for so much drink at mealtime will largely disappear. MH 305"
"What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?"
The verse speaks to the body as a temple, and EGW's passage provides specific instructions on how to care for that temple through proper eating habits. It's a practical application of the principle.
"Another serious evil is eating at improper times, as after violent or excessive exercise, when one is much exhausted or heated. Immediately after eating there is a strong draft upon the nervous energies; and when mind or body is heavily taxed just before or just after eating, digestion is hindered. When one is excited, anxious, or hurried, it is better not to eat until rest or relief is found. MH 305.3"
"Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God."
1 Corinthians 10:31 encourages doing everything to the glory of God, which includes eating. EGW's passage provides specific examples of how to eat in a way that honors God by caring for one's body and avoiding practices that hinder digestion.