Yes, the whale was probably extremely nourishing. Also, I modded the unicorns to [PET] and to giving milk which could be turned into cheese... and since there were dozens of unicorn herds roaming the map, the dwarves later on did eat not much else but unicorn eye roasts with minced unicorn cheese. Delicious and perhaps very rich in calories.
But I tend to lose interest in my DF2010 fortresses extremely quickly (as soon as I hit the caverns layers, which interrupt my central staircase, and realize that the magma is down 120 z-levels, that is), so I will monitor the weight development in my new fortress.
That, and the fact that there are literally no sentient/civilized survivors on this planet, except my dwarves and the cyclops tribe who killed everyone, might keep me interested.
I wonder if there will be immigrants... the last dwarven civilization fell in 117.
Anyway, at the start only one of them (Lor, farmer) was "fat"; the rest was apparently average (no mention of the fat at all); or even "skinny" (Bomrek, doctor) and "very skinny" (Catten, metalsmith).
In early summer, they are already changing their weight.
Lor: "corpulent" (from "fat")
Bomrek: "thin" (from "skinny")
Erith, expedition leader: "not very tall, but makes up for it with large layers of muscles and fat" (from "not very tall, but muscular")
Catten: still "very skinny".
Deler (stoneworker), Lokum (woodworker), Nomal (miner): no change.
The only ones that really worked so far were Nomal (mining), Erith (pumping some aquifer saltwater into a reservoir for desalinazing), and Lor (farming). The others mostly socialized.
There won't be whales on this map, and I brought some kittens and a breeding pair of two-humped camels with me. Outside is nothing but a freezing arctic sea and a freezing tundra (no trees, no shrubs). I've seen a muskox herd and one member of the cyclops tribe.