text: can you lose weight by excercising?? we had an argument between me and my mother... can you lose weight by excercising? cuz my mom said that you will only gain muscles... how is it realy?? and other one... can you lose weight from bottom and thighs by aerobic excercises or will you only have muscle legs? aaaaaaaaaaaaaaaahhhhhhhhhhhhh.... your mother is wrong! aerobic excersize does not increase muscle mass but rather burns calories, hence you lose weight.  weight lifting increases muscle density, hence weight gain weight due to increased muscle mass....