That's the way I meant it, but could have better expressed it, which I'll go do now. And that's how I read the original: an All Milk, Only Milk Diet.I think, Copyright, that "only" drinking milk for a month would probably cause you to lose weight. I interpret it to mean "nothing but milk" for a month. I could be wrong, never having been silly enough to try it.
Certainly a less messy interpretation than mine, and that sounds very plausible.Another possibility - bathrooms have mirrors and people sometimes keep their weighing scales there. It's therefore a room that could remind you of your weight and so give you "bathroom blues". (The word "blues" can mean a depressed mood.)