The "eating like x for a day" genre isn't really for me, but it seems like Youtubers usually go out of theit comfort zone more. Someone who creates fitness or bodybuilding content might eat raw, might eat stuff from fast food chains for the day, try to get free food, eat on a really low budget, eat food from another country's cuisine etc. With her food videos and the morning routine swaps, it seems like Holly just picks routines because they are similar to how she lives her life already, which... isn't exactly riveting content
Now, if she isn't comfortable doing something fast food based, that's fine, it's not like you need to be able to eat McDonald's for a day in order to be recovered from an ED. Eating like a bodybuilder could be fun and should be possible to do on a vegan diet, or only eating e.g., Korean or Indian or Chinese food (or maybe from the Oceania region, since she likes Australia) could mix it up a bit... savory breakfast options, cooked food, doesn't have to be the hot kind of spicy but can include more than just turmeric sprinkled on food. I'm not a good cook but like to try new things, and content showing how to cook something can be helpful in that way too (whereas, shocker, I already know how to boil rice and steam veggies). They shop at Aldi a lot and eat a lot of affordable staples, but eating on a budget for a week (where protein powder, a lot of seeds and nuts, avocados etc aren't all easily attainable) could be interesting, too - just to try out something new, not bc I think Holly is sending an especially problematic message in that regard.
I came across a TikTok the other day that went like "when you think you have covid symptoms but remember you're in England and that's just what the food is like" I had to think of Holly's food...