Energy required to magnetize soft iron?

[Dash-IQ]

Out of all the formula's I studied, I could not figure out how much energy is required to magnetize soft iron ferromagnetic material that has a small hysteresis loop(Due to the low coercive force)...
How can I figure this out?

Also magnetization energy = demagnetization energy correct?

 

[Dash-IQ]

Maybe I can figure it out from the torque applied on each moment in the material and know the magnetization energy?