Realistic rate of weight loss

What do you think is a realistic and healthy rate of weight loss?

I've been losing 1KG a month which might sound fairly easy but is proving to be quite difficult as i've developed a lot of muscle at the same time. This has been through a fairly radical diet change and 2-3 gym sessions per week on average.

I read about weight loss programmes that suggest 1KG per week but the weight will come back on IMO.

It depends how youre training, when i first started, (back when i was nearly 15 stone) i lost weight ludicrously fast to start with, then leveled out at about 13 becuase the muscle id put on (was doing a lot of weights) started to cancel out the fat id lost.