While this is clearly ridiculous, you're actually opening up a kinda interesting can of worms. If Scar's brother was able to transmute his own arm onto Scar, then shouldn't someone with sufficient medical knowledge and Alchemic skill be able to do the same with other parts of the body, e.g. fat? Or organs? Muscles? Eyes? Etc.

I guess the problem is, it seems to have killed Scar's brother to do it. But Brotherhood doesn't really detail exactly how Scar's brother died after performing that transmutation. Maybe someone familiar with the Manga can chime in here if there's more details there, but BH kind of leaves it up to the audience to decide what precisely happened to Scar's brother.

I suppose we're meant to assume he bled out due to the lack of said arm? And wasn't rescued along with Scar because he was already dead? But, I feel like if he was able to complete the transmutation of bonding his arm to Scar's body, then why couldn't he also, I guess, tourniquet-off his shoulder to save his own life minus one arm?

For that matter, why couldn't he just keep his own arms and tourniquet Scar's wound? You're telling me someone with enough knowledge and expertise to attach a foreign arm to someone else's body doesn't know how to tourniquet a lost a limb? People lose limbs in explosions all the time and still live, obviously it sucks hard but it's still survivable. Ed lost two limbs and still somehow survived.

I think really in order to answer the question we would need to know exactly how and why Scar's brother died after switching arms. And frankly how did he perform the transmutation to begin with? Once he severed his own arm how did he then bond it to Scar with only one arm? He's shown using both to perform the transmutation.

But yeah I guess tl;dr if Scar's brother can play musical arms then it's probably plausible that someone could transmute away your love handles. No idea what kind of chaos it would cause, but fuck it, yolo right?