I just tried an experiment. Both myself and my student tried a turnback at a safe altitude. He lost 700ft.
I was able to get round on the 3rd try with 400ft loss, rolling hard into 60 deg steep turn, but still IAS came down from 74 to 63 kts even with significant forward pressure to keep the wings unloaded, rolled bast the 180 deg by 30 for 5 seconds then back to the 180 deg mark.
C172SP at 3000 pressure height. Smooth air.
Someone who was un prepared for the power loss would lose even more alt. As well it takes considerable skill to set the exactl attitude during the turn, so the average weekend warrior would have no hope of getting it right.
My best was 400 ft height loss and I am doing this stuff day in day out.