Question: "What does the Bible say about nutrition? Should Christians emphasize a healthy diet?"
Answer: The subject of nutrition, as we think of it today, is not directly mentioned in the Bible—that is, the Bible doesn't talk about calories and the balance of fat, protein, and carbohydrates a person needs. Neither does it mention GMOs or the benefits of eating whole foods versus processed foods, because the production of food had not yet been industrialized. Furthermore, there was no scientific understanding of the elements in food and what they do to and for the human body. However, from biblical principles we can deduce that it is beneficial and even morally right to emphasize a healthful diet.
First of all, the Bible encourages us to care for our bodies, and good nutrition is naturally part of that. God cares about man's physical comfort and well-being (Exodus 22:27). Paul argues that, since a believer's body is a temple of the Holy Spirit, he should flee sexually immorality, which harms the body that was bought by Christ's blood (1 Corinthians 6:18–20). This argument can be carried over to other issues, including drug and alcohol abuse and how we treat food. Food is fuel. It is not meant to be used purely for pleasure, or we could eat nothing but chocolate and cheese pizza and be healthy. Food is meant for nutrition and good health.
Our bodies can be considered machines that carry us from place to place as we carry out the work God has planned for us (Ephesians 2:10). An unhealthy body will make us slow, lethargic, and prone to illness and injury. Good nutrition is crucial for proper brain function and hormonal balance; eating the right food contributes highly to our ability to think clearly and to our general quality of life. Therefore, good nutrition can help support our service for the Lord.
God gives food to us, as he does to the creatures of the animal kingdom (Psalm 147:9; 104:27; 136:25). The earth has been created to produce foods that are full of vitamins and minerals and amino acids that the body needs to survive and be healthy. Food is a gift from God; it is His provision. Why do whole, raw, unprocessed foods contain the most nutrition? Because they come right from God's hand.