"The need of carefulness in habits of diet should be impressed on the minds of all students. I have been instructed that those attending our schools are not to be served with flesh foods or with preparations of food that are known to be unwholesome. Nothing that will serve to encourage a desire for stimulants should be placed on the table. I appeal to all to refuse to eat those things that will injure the health. Thus they can serve the Lord by sacrifice. CT 298.1"
"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? For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s."
EGW's statement about avoiding unhealthy foods to maintain health aligns with the principle in 1 Corinthians 6:19-20 that our bodies are temples of the Holy Spirit and should be used to glorify God. Taking care of one's health through diet is a way to glorify God in one's body.
"I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service."
Both passages encourage a form of sacrifice related to the body. Romans 12:1 calls for presenting our bodies as a living sacrifice, while EGW encourages refusing to eat things that injure health as a sacrifice to the Lord.
"Those who obey the laws of health will give time and thought to the needs of the body and to the laws of digestion. And they will be rewarded by clearness of thought and strength of mind. On the other hand, it is possible for one to spoil his Christian experience by abuse of the stomach. Those things that derange the digestion have a benumbing influence on the finer feelings of the heart. That which darkens the skin and makes it dingy also clouds the spirits and destroys cheerfulness and peace of mind. Every habit that injures the health reacts upon the mind. That time is well spent which is directed to the establishment and preservation of sound physical and mental health. Firm, quiet nerves and a healthy circulation help men to follow right principles and to listen to the promptings of conscience. CT 298.2"
"And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God."
The EGW passage discusses the importance of physical health for mental clarity and spiritual well-being, which aligns with the principle of renewing the mind in Romans 12:2. The connection is that caring for the body impacts the mind's ability to discern God's will.
"For as he thinketh in his heart, so is he: Eat and drink, saith he to thee; but his heart is not with thee."
The connection is weak, but Proverbs 23:7 touches on the connection between the heart/mind and physical actions (eating). EGW elaborates on how diet affects mental clarity and Christian experience. The link is not strong enough for a 'thematic parallel' but there is a possible connection.