Albert Barnes Commentary Daniel 10:3

"I ate no pleasant bread, neither came flesh nor wine into my mouth, neither did I anoint myself at all, till three whole weeks were fulfilled." — Daniel 10:3 (ASV)

I ate no pleasant bread - Margin, bread of desires. So the Hebrew. The meaning is that he abstained from ordinary food and partook only of that which was coarse and disagreeable.

Neither came flesh nor wine in my mouth - That is, he lived on bread or vegetables. It is not to be inferred from this that Daniel ordinarily made use of wine, for it would seem from (Daniel 1:0) that this was not his custom. It would appear from this passage that he practiced on this occasion the most rigid abstinence.

Neither did I anoint myself - The use of unguents was common in the East (see the notes at Matthew 6:17), and Daniel here says that he abstained during these three weeks from what he ordinarily observed as promoting his personal comfort. He gave himself up to a way of life that expressed deep grief. Nature prompts this when the mind is overwhelmed with sorrow. Not only do we become indifferent to our food, but it requires an effort not to be indifferent to our dress and to our personal appearance.