At the end of the ten days, Daniel and his three friends looked healthier and better nourished than the young men who had been eating the food assigned by the king … God keep these four young men an unusual aptitude for understanding every aspect of literature and wisdom. And God gave Daniel the special ability to interpret the meanings of visions and dreams.
– Daniel 1:15, 17 (NLT).
I once underook the Daniel diet test, subsisting on vegetables and water for ten days. Interesting things happened to my body as a result – not bad, just interesting. In the mix of this I also took to a lot of walking and exercise. Interestingly, I did not suffer that much of a lack of energy. Did I miss the luxuries of Western diet, even a vegetarian diet? No question. But God's Spirit taught me a thing or two …
One of the theological truths surrounding this story in Daniel is God's esteem for Daniel and his friends' faithfulness to not defile their bodies with King Nebuchadnezzar's rich, royal food and wine. You may recall that were basically prisoners of the royal court as Judah was being progressively taken into exile to Babylon (c. 605 BCE – about twenty years before the actual exile). They were not in a position to pick and choose what they ate and drank.
However, Daniel had other ideas. Daniel not only resolved to not partake of the royal diet, it was his method, implied in the Scriptural text, that sets his example apart as wise, discerning, authoritative and assertive. Instead of stamping his feet and demanding his way (which would've risked death), he calmly problem solved, and came up with a way to convince the royal guard of the veracity of his idea.
It needed to be a "bodily" win / win exit. The guard needed to be assured their bodily conditions would not suffer as a result of being on such bland regimes and it needed to allow Daniel and his friends the obedience to their God by keeping their bodies pure, in keeping with their beliefs – even in exile. They'd been found to be 'qualified to serve in the king's palace' because they were, "without any physical defect, handsome, showing aptitude for every kind of learning, well informed, quick to understand." (v. 4; TNIV) Changes to their diet could not threaten their qualities for service in the king's palace.
From the practical perspective we know food's made of protein which repairs and builds the body's cells and tissues, fats (essential and non-essential) and carbohydrates. All foods provide, or can convert into, energy for the body to burn as fuel – however, the body prefers starchy carbohydrates. We also know, as an extension of these facts that a vegetables-only diet, while not only being bland, also struggles to compete on both the body repair and energy stages.
Yet, God demonstrates something here, not only to Daniel and his friends' through their faith to subsist on the meagre diet, and to the royal guard – who must have been quite astounded as to their, if anything, enhanced health, but God also proves something to us. Indeed, at the mount of temptation after fasting for forty days and forty nights, Jesus quotes Deuteronomy 8: 3 when he's tested by the Devil to make bread from stones:
It is written: 'People do not live on bread alone, but on every word that comes from the mouth of God'.
– Matthew 4: 4 (TNIV).
The person who can live either in abundance or poverty, whether it be food, money, material or spiritual things, is the mature person. Paul discusses this in his book of joy 'to the Philippians:
I have learned the secret of being content in any and every situation, whether well fed or hungry, whether living in plenty or in want.
– Philippians 4: 12b (NLT).
And this is the most wonderful Gospel reality. Nothing can defeat us when we've reached this place, the pinnacle of godly certitude. It's a place all must strive for if joy and contentment, notwithstanding faithfulness, are the aims.