How do you lose muscle mass?

Answer 1

by doing long endurance cardiovascular activities--such as distance running, distance cycling, jumproping, etc

cardio generally eats away at muscle mass--and tones them--and makes them long and lean

if you just do cardio and not weight lift--you'll lose significant amounts of muscle mass

Answer 2

Not using the muscles leads to reduction of muscle mass.

Answer 3

Eat a pint of ice cream everynight, do not work out

Answer 4

Just stop working out.