But the odds are that someone who is thin has a healthier lifestyle than an obese person.

A Google search for “Halloween costumes plus size” (using the quotes) returns 108,000 results. There’s clearly a demand and market for the product.
In fact, just Party City’s site has a wide variety of appropriately designed and scaled costumes for both plus size men and women. They’re just not Disney licensed. If a woman wants a “flirty” or “sexy” plus size Snow White costume, then she can get it there – along with the Queen of Hearts (in sexy or formal), Mad Hatter or Alice in Wonderland (naughty or nice). 

http://www.partycity.com/category/halloween+costumes/plus+size+costumes.do

Halloween Express chose to have 196 options (including a few unlicensed Disneys) for just plus size women.

http://www.halloweenexpress.com/plus-size-costumes-c-434.html

This is NOT a question of demand and cost. Demand exists. It simply isn’t being met by product.

This year, as much as it pains me, I may skip the Halloween costume entirely.

Never mind the “sexy peacock” costume I’ve also been seeing, which, inexplicably, is being worn by a woman. Clearly that costume was designed by a heterosexual male who knows nothing about peacocks, but presumably has a feather fetish (not that there’s anything wrong with that).

I can buy that a college student might want to dress up “sexy” for Halloween, but I cannot fathom that most 8 or 9 year olds would. I’m not sure what is driving this trend toward trashy Halloween costumes, but I don’t think it’s market demand. I think this is what the costumers are cranking out and people make do with the limited choices.

–FIRST:  general giant UGH to all of the “sexy (insert job description or character name here)” costumes.  Just ugh.  Also note that these kinds of costumes are 100% aimed at women (ie you can get a Sexy Darth Vadar costume for women, but no men’s version consisting of a mask and a black vynil marble bag).  Blah blah freedom of choice blah it’s OK for women to be sexy in public BLAH yeah I know. 

–NEXT YES to whomever pointed out that all of those premade costumes, sexy or not, run small for women.  So do clothes in general.  When I was lifting weights and working out 5x a week between jobs, I got my BMI down to 19 and I looked like freaking Wonder Woman with smaller boobs and a crewcut.  BUT my Big Ol’ Russian Jewish Ass still meant that I needed size 16 jeans, flat belly or not.  Finding ANY clothing, nevermind costumes, was and is a chore.  OTOH a good friend of mine is self-admittedly morbidly obese, and he can get a suit off the rack that fits him for around $100 in a multitude of places, no muss no fuss. 

–YES to fat chicks still being able to be sexy.  It’s just that right now, societal norms openly mock anyone over the “perfect” weight for WANTING to be sexy, so clothing/costume options are limited. 

–BUT a stunning number of men like women with some meat (and fat) on them.  Obviously, YMMV, but one thing I’ve heard from guys I’ve dated/had relationships with (friendship, lover, etc) is that they hate picky eaters and borderline anorexic women.  Yes, it’s obviously self-selecting (guys who want a supermodel ain’t gonna ask for my number) but still….

–Finally, I am all for creative costume designs that start at home.  You don’t have to know how to sew, just take an idea and run with it.  One of  my favorite costumes of all time consisted of a black suit–ie normal guy’s suit, for the office–white kid gloves, and a sign around the neck saying “-ly” .  He was going as an adverb.

I’m 5′ 4″ and when I was about 135 pounds, which meant I was starting to look almost chubby., my measurements were about 37″, 31″ and 39″  That’s one size smaller, a 12.

Healthy range for 5′ 4″ is generally considered to be between 108 and 145.

I’d guess I’d hit size 14 at about 140-145.  I would be a bit chunky.  I’d look slightly overweight.

(For the record, I’m not actually dressing up for Halloween, but I am annoyed by the lack of availability of a plus-size Ursula costume if I or others of my body shape DID want to dress up and not have to learn how to sew first.) (I’m spending Halloween with my widowed father, as this is his first Halloween since my mother died and it would’ve been their 42nd wedding anniversary. So, yeah, if I had time to sit and learn how to sew and make a fricking strapless gown with tentacles, I’d totally do it.) (Sorry I’m such a lazy, uncreative fuck.)

But! Ursula is sexy. Her breasts! Her butt! The way she moves! Her voice! I don’t honestly remember really… noticing this as a child, but it’s there and it’s largely treated as… normal. Ursula isn’t evil because she’s sexy, nor does she seem really to be evil because she’s fat. She’s just evil and fat and sexy, all in the same package, and I guess that’s kind of cool? I’m not sure.

Persons of all sizes, shapes, and ages can develop type-2 diabetes. The primary factor is genetics, with not-insignificant contributions from epigenetic influences.