Go to the hardware store or feed store and lift something that is fifty pounds (box of nails, salt block, 50 pound bag of feed) Practice this a few times and get a feel for what that weighs. Lift the back of the hive. This time of year, in my location, it should weigh that much or more if it's a full cluster of Italian bees. A full cluster of Italian bees here would be about basketball sized or more. But they go down from there to Carniolans and Russians which are smaller and then the feral survivors who seem to be even smaller, and nucs I'm trying to winter...
The hive should be heavy. While you're experimenting, set up an empty hive. Just boxes and frames, or drawn combs and lift the back. That's an empty hive. If you lift a hive that is close to that weight, they are starving.