Timewarp, you really shouldn't see your dad as being against you throughout this. If you think about it rationally, having not eaten anything proper since Monday, if I was your dad, I would likely react the same way.
I suppose it's interesting how you shift cognitively as you slowly recover; things start to sound crazy. Some days I would just eat an entire cucumber. Now, I think, Jesus Christ, what the hell was WRONG with me? That's WEIRD.
Nowadays I hear someone saying, "yeah, I ate on Sunday, but I'm going for X calories for the entire week, so..." and I'm like, DINGDINGDING, ALARM ALARM.
Timewarp, I can't obviously make you change your outlook with a mere message, but... I think your dad may be erring on the side of poor tact, but overall, he's RIGHT to react as he does.