Whew. Here goes. There are several different types of fats, but the type this "rule" applies to most broadly (pun not intended) is the self-hating ham in denial (I'll refer to them as SHHID from hereon out). SHHIDs are easily identified by their behavior and purchases. Unlike the proud hams, they aren't content with pretending they enjoy being fat. So they're always at the gym, buying workout clothing, posing with diet shakes on Instaham, talking about their "journey" through weight-loss and so forth. In spite of everything they purportedly do, they still remain exactly the same size, in some cases ballooning even bigger as time goes by. The SHHID isn't happy with being fat, but it's content with others merely seeing that it isn't. Essentially, it is the "A for effort" expectation.  The reasons for this behavior can vary, but a popular one can be somewhat likened to alcoholics that stay alcoholics but keep telling others they're going to get into a program, that this drink is the last one -- they just say it to get people off their backs. Like fats, they aren't happy being alcoholics, but pretending to give it up is easier than actually trying to quit. In the case of hams, there are way more ways to demonstrate you're trying to lose weight than there are quitting substance abuse. Telling a SHHID "You'd be pretty if you weren't fat" is fat sympathy because it reinforces the toxic rationalizing of the fat and encourages its pseudo weight-loss behavior. If the fat is interested in you romantically, it will expect you to enter a relationship with it. Why? Because it's in the process of not being fat, so if you get involved with it, you'll have the honor of watching it become prettier and prettier! It tells the fat that you're a safe person to date, because you will stay with it as long as it takes the easy route -- pretending to lose weight instead of actually doing it. Additionally, the SHHID lives for potential. Potential to get toned. Potential to be beautiful. Potential to lose those pounds and be desirable. Confirming that potential by telling it that you also see what it sees in itself is bad for obvious reasons. The moment it senses a decent non-fat agrees with it, it will pounce and try to get into a relationship -- and in some cases, it succeeds and remains a hamplanet, but with an enabler comforting it even further. The most shitlordy thing you can tell a SHHID is "give up." That's it. "Give it up, ham. You're a worthless tub of lard. You'll never lose that weight, you're an ugly sack of shit at every weight, give up and accept you'll always be this way. Don't waste your time and money, no reasonable human will ever want you." It takes away any notion of pretense it thought it had -- you're telling it that you see through the gym pictures, the sweaty selfies, the massive post "work-out" meals and so on. It isn't fooling anyone and you've called it out.