Voltage Stabilizer Efficiency Loss (Extra power consumption)

Hello All,
I am using an 1KVA Voltage stabilizer for my Fridge. The power quality is really poor here in India, and these things are mandatory. I learnt the lesson hard way :-(....
Well that aside, i would like to know what would be the power loss or Extra consumption these devices use when regulating power.
Actually,i could use a general lecture on how Stabilizers work!

It depends entirely on how it works. The classic method is really lousy, using special trandformers which run lossily. Look up "saturable inductors".

As you surmise, they are not at all efficient. A more modern approach uses electronics, and they could be 80% plus efficient.