Well, they are a social construct. As is clothing in general. That doesn't mean you can go around town in your birthday suit, though!  Social constructs exist because we live in a society that calls for them. Don't like it? That's fine, you can move to a nudist colony!  Accessible, affordable healthcare is a social construct. Disability support is a social construct. The right to clean, safe water is a social construct. Living near places that sell food is a social construct. Our language is a social construct. Social media is a social construct. Sleeping with a roof over your head is a social construct. Engaging with your peers and having friends is a social construct. Getting paid to work is a social construct. Freedom of expression is a social construct. Criminalizing theft, kidnapping, rape, murder and fraud? Social construct. The right to defend yourself against the aforementioned crimes? Social construct.  Pants? Social construct. Among other things fatties (and the rest of us) rely on in our day to day lives.