What does Mark 8:16 mean?

Those combing the Bible for tiny questions, in an effort to discredit it, will compare this verse with Mark 8:14 and declare the Bible unreliable. It is true that they had one loaf of bread that they found in the boat, possibly left over from Jesus feeding the four thousand in Decapolis. If so, it's very possible it was at best stale and at worst soggy from water that splashed into the boat. Another possibility is that Mark is using hyperbole because the loaf of bread is too small to make a dent in the appetites of thirteen men. At that time, a "loaf" of bread was flat and about the size of a dinner plate. Such provisions would not have gone far.

The exact measurement of the edible food within the boat is not Mark's point. He wishes to point out that, once again, the disciples have set off without sufficient food, and that by now this should not be something that should concern them. As Jesus will point out, within the last few months, they have watched Him turn a few loaves and a handful of dried fish into a meal for thousands—twice (Mark 5:68; 8:5–7)! But instead of handing Jesus the bread and asking Him to make sandwiches, they "discuss" amongst themselves.

The disciples now face the same issue that Jesus did during His first temptation (Matthew 4:1–4): they want bread but need a stronger relationship with God. When Jesus fed the five thousand (Mark 6:30–44), He did so only after the people had listened to Him. He knows that seeking physical comfort can distract us from what God has planned for us (John 6:26), which is why He refused to turn the stones into bread when Satan tempted Him. This is not to say we're never to care for our physical needs, or adopt deliberately harsh lifestyles (Colossians 2:20–23). What we should avoid is inappropriate pursuit of the physical at the expense of our greater spiritual needs.

Here, Jesus turns the physical truth into a metaphor. The teachings of the Pharisees and the Herodians serve as a red herring that easily distract the people—and potentially the disciples—from God's truth. We must be careful to prioritize God's work in us and God's truth over ease and comfort.