Hi I'm pretty new to the STO universe have have finally met the borg.
Now I remember from the TV shows and Film that the borg were big and bulky, but on STO I was surprised to find they were tall and skinny, they look like anorexic borg???
I think they need to be fed so they can bulk up somewhat.

you have to remember that these borg are not the same borg you saw on TV/Film, considering it's 30 years after Nemesis in STO... and in that time, they've suffered many setbacks and defeats, so i'm not too surprised that the borg are showing signs of that in the drones

also, on the shows and films, weren't the borg covered by the black armor they wore? well, with the absence of that now, that might be why they're missing the big and bulky look

If you play one of the STFs later on, it features Borg from the TNG era. They are "bulkier".

I think the techno-zombie look is intentional (remember that Borg do not eat per se. They plug into a socket or alcove and absorb energy which their internal systems use to synthesize the needed nutrients (if I am remembering "I, Borg" correctly). That sort of diet would lead to most of the organs in the abdomen being atrophied/removed, thus the skeletal midsections on current Borg).

lol so what you are saying, you want to fight obese borg? lol just kiding

The processes required to fully assimilate a Borg may be similar to say, Egyptian mummification processes.
Borg nanoprobes may be the first step in assimilation, but adding the implants, removing organs, and getting people into the armor suit would be a process that could take days.
From what I recall, some of the early drawings of the Borg Queen also had her wearing a Nefertiti-like crown.

Also, the Borg may also want to make the full recovery of a Liberated Borg difficult to impossible without these organs, making them either completely dependant on the Collective for survival or making them dependant on additional implants after liberation..

Unfortunately, Borg drones don't have a decent worker's union that requires mandatory lunch breaks.