It sounds like you bought the ones in the auction I referred to in an earlier post. They haven't been supplemented at all, have been living on flies, fruit flies, and mealworms, but I don't know in what proportion each type has been available. (As far as I know they just cut a hole in the lid of each feed tub and left the tub in the enclosure, rather than feeding a specific number of critters per feed?) I've heard some litoriae will get lazy and gorge on mealworms rather than chase flies, so that might be part of it. I also didn't see any UV bulbs or heaters on the auction photos, so all of them are probably quite calcium-deficient.

A diet of mealworms will leave them chubby, but malnourished. Also watch for impaction, since the chiton on the mealworm exo-skeleton can apparently build up in their digestive tract and cause constipation, and if it's not fixed, severe intestinal blockage or even death. Maybe a honey bath will help the sick one?

I've looked for Repta-boost and so on in NZ, and not found it yet. Pipe up if you do find a source!