Depends, you ever been to strong man events? Or Gay Bear clubs? It also very much depends on what kind of fat you are. There’s fat but also muscly and strong, and there’s weak skinny fat with no redeeming physical qualities.
What I’ve noted about people, generally from the incel community who say this, is that they ignore the women who do match with them, who are in their league.
They really mean men are invisible to *attractive women*, they are visible to the ones who are on par with them, but they don’t count those women as for what ever reason (I think porn and social media), they think they are entitled to attractive women and grossly over estimate where they stand as equals in the sexual value market.
The only way to change this is for them to increase their sexual market value, but that tends to involve an awful lot of hard work, both mentally and physically, for any real gains. Much easier to be bitter and lazy.