No I guess there must be some people for whom it isn't obvious. I was kind of assuming the intended audience for the advice was people who are interested enough in diet to look at a book on nutrition, for example, not people who just eat junk without thinking about it.

But yes for those people I do think the "eat food" thing should be emphasised and laid out in more detail, maybe. Hard for me to have an opinion there as I just can't put myself in the shoes of someone who eats that kind of stuff.