both m3 and m4 have a emaciated  morph and a  young morph, maybe a skinny morph. 

the pic attached is m4 with morphs from BODY set to emaciated 2, young .5 and then some of the morphs for upper body , arms and legs set to make them thinner. A few morphs were set to negative values like chest size. All in the BODY actor. 

You should be able to get similar results with m3 .

You will need the morphs for either mike. I dont know of a free starvation morph.