I asked Cathe that once, but she never answered. From what I've read since, she prefers not to get into the nutrition arena as it is so complex.
I'm certainly no expert, but to me eating clean means whole grains, lots of veggies, some fruit, lots & lots of water, & some lean protein.
What it doesn't mean is, of course, saturated fats, white flour products, sugar, and just in general, "junk".
Having said that, however, I must say that my biggest struggle has been learning to eat more food & more often, rather than not eating certain things. But I'm sure that's different for everyone.
When I feel that I am far enough along to have a cheat day, I'm sure I will be having some chocolate!
This is hard, but it's a lot of fun too, now that we have buddies to cheer us on & share our pain!
Ruth