Hi,
I personally wouldn't if he was already eating mice or rats previously.
Hamsters can be hard to get regularly at an affordable price as well as the possible problems withy fat/ hair content.
What was he eating most regularly before? And how were you feeding it ( live, F/T etc )?
You can also try chicks - I don't like them as a major part of the diet either to be honest but they are quite cheap and tend to come in bags of 50 so that's one problem less.
How much does he weigh just now and how much do you think he has lost?
dr del