Almost any fat loss will probably have a lean tissue loss as well as there is a lean component to fat tissues.
What will maintain muscle seems to be maximum tensile load. If a person maintains their peak strength for a lift, they probably haven't lost any of the muscle used for that lift.
I would say a deficit of no more than 1% of your bodyweight per week (that would be the maximum), adequate protein (0.8-1g per lb goalweight) and following a proper progressive lifting program .. those are the basics to help maintain as much muscle in a deficit.
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I lost 30 lbs in 100 days and lost 0.7 lbs of muscles. I am happy with those results.
What will maintain muscle seems to be maximum tensile load. If a person maintains their peak strength for a lift, they probably haven't lost any of the muscle used for that lift.