I think when people say weight loss they mean "fat loss". Steroids can help reduce fat by:
-Increasing metabolism (different from increased lean mass)
-Building more muscle which burns more cals per unit time
I've read about cutting cycles that involve test, but the core is still diet and exercise, but test can enchance the effect.
Just keep in mind the scale may go up due to water retention etc.. but Bf% should go down.