There's an intensity of desire to be "victimized" by fat acceptance-fat people in general for a similar reason. It's like FA's a wall and folks keep taking a long run at it hurling themselves hard, bouncing off and saying
"That wall hurt meeeeee!"
Still, certain things seem to irk FA detractors. One is calling those who've managed to acquire anorexia, or long term dieters, "freaks of nature". Yep, this (still) has boo boo traction.
I wouldn't describe those who sustain a diet long term as "freaks of nature". It's not rude, just off kilter. It makes me think of those at the extreme ends of the weight scale.
I'm sure many of us assume they have some clear genetic predisposition to be at the top of the scale but it doesn't appear to be so simple.
Looking from the perspective we've been trained in, getting overexcited about people who's BMI is greater than 25, you'd expect those double that or more to have a more distinct sign, pattern or marker of difference.
Although some interesting possibilities and differing susceptibilities definitely lend themselves to weight gain, for various reasons. There isn't consistent uniformity over and above a propensity to gain (in some cases lose) weight. A spread of traits and/or genes of certain types more likely to congregate at certain points-like for instance the deletion mentioned or at the other point duplication, though they don't seem wholly deterministic in themselves.
The most unusual thing about weight outliers-of all types, including those of least weight, is that they are where they are.
Whether they're "reduced obese" or at the lower/ higher end, the most remarkably distinct thing about them, is that they are and they actually aren't "freaky" enough to signal why they as opposed to others who may (or may not) share their traits aren't.
That's an underlying truth of many conditions. So many more people fit the criteria for the activated state, but it's somehow dormant or inactive. The the trigger or spark or lack of it, is the real mystery.
Inside and outside genes (those who have genetic susceptibility to be lower/higher weights and those who do not), probability plays out. Low rate of chance means a relative rarity, has occurred. Yet probability doesn't have intent and the multifaceted complex and reactively nuanced nature of human metabolism is the closest thing to that beyond the interplay of environment and DNA.