You must declare that you are using this feat before you make your attack roll (thus, a failed attack roll ruins the attempt). Stunning Fist forces a foe damaged by your unarmed attack to make a Fortitude saving throw (DC 10 + ½ your character level + your Wis modifier), in addition to dealing damage normally. A defender who fails this saving throw is stunned for 1 round (until just before your next action). A stunned creature drops everything held, can’t take actions, takes a -2 penalty to AC, and loses his Dexterity bonus to AC. You may attempt a stunning attack once per day for every four levels you have attained (but see Special), and no more than once per round. Constructs , oozes , plants , undead , incorporeal creatures , and creatures immune to critical hits cannot be stunned.
Many Skinny people think they have a high metabolsim blah blah. the truth is, if you nibble on biscuits n stuff that really dont have much protein or starch, you wont gain anything. if you want to gain weight you have to sit down n eat like u nuts. meals you cannot afford to skip are breakfast n supper. always eat alot before you go to bed. u will always wake up hungry n wont have to really force breakfast in. its not that you dont eat. its jus that you dont realise that u fill up your stomach with air n water. another thing, try working out. the problem with skinny people working out is that they dont realise that spending the whole day in the gym actually works against u. YOU GO TO THE GYM TO BUILD MUSCLE NOT BURNM FAT! spend a maximum of 45 minutes in the gym n learn to rest your muscles. use heavy weights and do 3 sets of each rep. dont rest your muscles till the 45 minutes are up. drink lots of water too.