The Bible is full of indications that God cares about our appearance. God created us "in his own image," (Genesis 1:27), He designed each of us in the womb (Jeremiah 1:5), and "we are his workmanship" (Ephesians 2:10). He made each of us to look just as we do, and we reflect His own beauty. The Bible doesn't say how we reflect His beauty, but it is reasonable that our appearance has something to do with that. Since God cares about our appearance, we ought to as well.
Is physical appearance something Christians should care about?
However, as God told Samuel when Samuel was looking for someone to anoint as king to follow Saul in 1 Samuel 16:7, "… the LORD sees not as man sees: man looks on the outward appearance, but the LORD looks on the heart." If we are to have the same attitudes as Jesus has, we should place our priority on how our heart is in relation to God. Outward appearance may be important, but the heart is more important. Samuel looked at each of David's brothers, and he was sure God would have chosen one of them. But God had chosen "a man after His own heart." (1 Samuel 13:14). David was good looking (1 Samuel 16:12), but God had chosen him because of his heart, not his appearance.
People often look at 1 Timothy 2:8-10 ("I desire then … that women should adorn themselves in respectable apparel, with modesty and self-control, not with braided hair and gold or pearls or costly attire, but with what is proper for women who profess godliness—with good works.") when addressing the issue of caring about physical appearance and apply it to say that women should not wear expensive jewelry or wear fine clothes. However, as Titus 2 says, the principle that our adornment should be in godliness rather than outward appearance applies to all people, regardless of their age, gender, or station in life. Both passages of Scripture are addressing the issue that proper godly attitudes are much more important. So, if we care about our physical appearance, the reason we care is much more important than the fact that we care. For example, if we keep fit and trim because we want to glorify God in our bodies (1 Corinthians 6:20), we have a good reason for doing so. But if we keep fit and trim because we want to impress others with how in shape we are, our reason is pride, which the Bible condemns in many places. One such scripture is 1 Peter 5:5, which says, "God opposes the proud but gives grace to the humble." If we obsess about our physical appearance, we may be falling into idolatry, which is also condemned throughout the Bible (Colossians 3:5, for one passage). So we should care about physical appearance, but outward appearance should not be what we focus on. We should focus more on why we care about our physical appearance than how we look.
The world places quite a bit of emphasis on physical appearance, but Christians should "not be conformed to this world, but be transformed by the renewal of [our] mind[s], that by testing [we] may discern what is the will of God, what is good and acceptable and perfect" (Romans 12:2). We should not reject caring about our physical appearance just because the world cares, but we should be changed inside so we can tell what the will of God is. If His will for us is to minister to the "beautiful people," we probably should look the part so our physical appearance does not detract from our ministry. Our reason for paying attention to how we look should be to please God, not other people.
Therefore, the answer to the question, "Should Christians care about physical appearance?" is "Yes", but with the very strong caveat that our reason for caring should be that we want to please God in our bodies.
How can I stay focused on Christ?
How can I seek first the kingdom of God?
What does it mean for Christians to be in the world but not of the world?
Should Christian women use make-up? What about jewelry?
Is it okay for a Christian man or woman to wear earrings?
Truth about the Christian Life