The theme parks not only had overpriced crap food (and you are not meant to bring any food or drink into the park), but also pretty much zero options for the low carber. At Dreamworld for example by about 2 in the afternoon I was starting to get a little hungry so went to the food places to see if anything was suitable, pretty much nothing and I sure as shit was not paying $15 for a burger, fries and drink that would be mostly thrown away, no single burger purchase allowed.
My wife ended up with a prepackaged Ceasar salad with something that tried to pass itself off as slices of ham, and as I found the look of that pretty damn unappealing I ended with a small packet of peanuts to tide me over until I could get some real food. That did work remarkably well at satisfying my hunger for a few more hours.
Movieworld was pretty much the same carb fest as dreamworld and so were the food courts in most of the malls and shopping centers unless you went to a proper sit down restaurant. However I did manage a couple of low carb meals on the run, a prawn salad at a seafood place and half a small chicken at a roast type place.
Restaurant eating was much easier, most of the places we went to offered buffet style dining which I could pick and choose what ended up on my plate, which was great.
We did also stay in self contained apartment which also made breakfast and evening meals much easier, allowing us to cook in a full kitchen.