The hominids we're descended from went through a similar crisis (we went from year-round fruit to seasonal availability). The ones who survived (and so became our ancestors) had something called the uricase mutation.
This mutation meant that fructose (something common in ripe fruit) caused them to store fat away for the coming hungry period. It does this via levels of uric acid - and is somewhat common in the animal kingdom (birds who migrate long distance, for example). It's also become clear that we mammals can generate uric acid through periods of thirst (what the biologists would call 'high osmoality') which in turn triggers fat storage and the production of water from that fat. As you might expect, it's common in sea mammals, If you're wondering how a big filter feeder like a humpback gets fresh water to drink - they pretty much don't but use this system.
The TL;DR: of all this is that fructose (BTW sucrose AKA sugar is half fructoose) and getting thirsty both trigger our 'store more fat' uric acid system.
I'm on a mobile so no links, but if you're looking for further information Dr. Rick Johnson has published a number of studies (and written at least one book).