There is no way you have that from historical research. Afaik, that level of notes keeping and detail was not available at the time.

In general, in situation like these, the first to die are sick, old/kids and those suffering from malnutrition. It would be super safe to guess that Leningrad at the time and a lot of those (given general state of that country).

It's not from a research, but from the memoirs of those who survived. So it might be not accurate, indeed.

Maybe they're more likely to be eaten?