A portmanteau of "infinity" and "fat" originating from the BBW (Big Beautiful Woman) community in 2017, initially referring to wearing size XXXXXXL or larger. It slowly enlarged to encompass the HAES, Body Positivity, and Fat Acceptance movements. It has increased its scope beyond women's clothing and has since ballooned into a large-scale intersectional movement.

As the term has grown wider in usage its breadth encompasses those in the CDC's highest level of weight: Class III Severe (Morbid) Obesity. Although Class III starts at a 40 BMI, infinifat's are typically closer to a 47-50+ BMI. For a 5'5" woman this equates to a weight surpassing 300 lbs.

Infinifats view lesser BMIs as small-fats, mid-fats, or superfats (coinciding with Class I, II, and the lower-end of Class III Obesity) as having "thin privilege". Examples cited: being able to buy ready-to-wear (RTW) clothing from typical "Plus-Sized" shops (usually limited to XXXXL) and the ability to use typical body weight scales (that work to only 300 lbs).

Infinifat is debated as "gatekeeping" causing tensions within the increased scope of its expanded community and slow migration into intersectionality.

Many infinifats, e.g. Tess Holiday, claim recovery from an Eating Disorder (ED), Anorexia. Those within the opposing "Pro-Ana" (Anorexia) ED-supportive community say such claims coming from "Fat Acceptance" advocates are farcical and reflect a different ED: Binge-eating Disorder (BED) or more accurately, Tessorexia.
Bertha: I had to purchase two seats on the airplane because of my weight.
Tessa: Getting to purchase a single ticket on an airplane is an example of thin privilege that is denied to members of the infinifat community.
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Olga: My doctor suggested I met the requirements for weight loss surgery due to my 40 BMI. I told her that I'm recovering from my anorexia and that suggestions of weight loss surgery are highly offensive and harmful to us infinifats.
Tessie: You're just "mid-fat", not "infinifat". You still have thin privilege like finding clothes in your size.
by SmurfberryDreams July 30, 2021
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The next stage in obesity after deathfat and superfat with an extremely high and very unhealthy BMI.
Unfortunately, Sandra is bed bound because she is an infinifat.
by OobieDoobie May 14, 2018
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A person who is size 34 or higher or wears size 6x and up. Most clothing lines do not offer these sizes and people who are this size have to shop online or require custom sizing.
People who are infinifat are more oppressed than small fats as clothing is not easily Accessible to them.
by Anabanana425 July 1, 2021
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