Masochists, why is my gf so turned on by humiliation and body shaming?

[You have a gut]

My gf is conventionally hot, although she's gaining weight, but since I met her she's been very turned on by submission and humiliation particularly body shaming. Even before we were an issue I've been body shaming her ina playful way, and she seems to love it, ahe even does it to herself. As someone with no masochistic tendencies at all, I find it hard to believe someone can be turned on by that if she doesn't have deep self-esteem problem, but she just seems so happy and jouful about it. It makes her grin like a child on Christmas day, she really seems to be hooked on it. 

I remember her saying at the begining of our relationship "They say men are intimidated by me", so i guess the fact that I never seemed intimidated by her might have been refreshing, but far from fading away her feelings seem to be getting stronger. She also mentioned that submission makes her feel liberated.

Can anyone with similar tendencies shed some light?

[vpprof]

When you engage in submissive behavior or let yourself be humiliated, you're being vulnerable, that is, prone to being harmed by the other party. This "harm" needn't be severe or illegal, it's just the idea. Normally with a stranger, you defend yourself. What makes the difference between strangers and close ones is lack of these defenses in the latter case. Some even define intimacy as letting one's guard down. 

So if you're at someone else's mercy and this other person decides not to harm you — e.g. "you fat pig, you can barely move, I need to care for you" — that proves their intentions are good. That equates with a bond being forged with this other person. The greater the scope for the harm, the stronger the bond. In another thread, wolves were mentioned. When wolves fight for dominance, the defeated wolf lies on its back, which must surely be the most precarious position possible, and then exposes its neck and throat, as though daring the other wolf: “Kill me if you want!” That's the deal. You could kill me but you decided to spare me.

A sense of bond is necessary for all the pleasurable stuff that happens in the bedroom, even if in reality the partners are strangers. They might be strangers but deep inside they pretend to themselves they have a bond.

The need to submit is especially strong in (but not exclusive to) people who have elevated anxiety and seek some sort of a guardian — be it a "daddy" or a muscular girl.

The above holds true for many other paraphilias (kinks), such as people attracted to amputees, individuals with mental issues, destitute, addicted or otherwise impaired. In women it often assumes the shape of "nursing" or "helping" the partner. Theory has it, that intimacy can be achieved without these symbolic means.

[extra_m13]

mind is very complex, anything can be super weird looking from the outisde and anything can have a lot of reasons and none at the same time, just for being. personally i can understand why someone looks at me strange when i say i love fat girls and that seeing a girl overeat is the max enhancing so... probably talking openly about it can give you some hints. that is the main key in my opinion.