Outlaw Star/Headscratchers

What was the liquid in the bowls Aisha drank when Gene "bought" her that apology meal? I.E., "What's with Ctarl Ctarl biology and ingesting massive amounts of water?"
Aisha referred to her problem (in English) as specifically expending too many calories. However, the two enormous bowls she drank looked like and sounded like soup, of the mostly-water type (perhaps some sort of miso-with-delicious-red-stuff soup). If calories really were her problem, wouldn't she have preferred to eat something with a higher caloric content and less impossible-to-break-down water, like roux or blood gravy, and take in the water that she needed in a separate, more customizable way, such as in smaller bowls of soup and tea? Did the japanese version just say she was hungry and not even mention calories? Was it mentioned very briefly on the show or in the supplementary material what the liquid was? Do Ctarl Ctarl simply have a biological mechanism that can absorb water really well and store it for later dispersal into their body systems? Am I over-thinking this