Fat people aren’t very visible on American television, and when they appear, it tends to be in one of a few approved roles: comic props in blue-collar reality series, cautionary figures in exploitative medical shows, huffing and puffing contestants in weight-loss competitions.

Alexandra Lescaze’s documentary “All of Me: A Story of Love, Loss, and Last Resorts,” showing in PBS’s “Independent Lens” series on Monday night, is a welcome exception. Its examination of obesity is serious, intimate and not at all sensationalistic, despite some graphic images of weight-loss surgery and its consequences.

And Ms. Lescaze’s film confounds expectations in other, more significant ways. “All of Me” follows several women in Austin, Tex., who are or have been part of a group of “big beautiful women,” with social lives and in some cases livelihoods tied to their size and the attraction it holds for some men. Now they are having (or saving up for) weight-loss operations, and while they are eager to lose weight, their feelings about it are anything but straightforward.

Friendships and relationships shift and strain as a woman’s size and possibly her outlook on life change. Husbands feel threatened by a wife’s new look, or insecure about their own girth. Conversely, women who were hired as fetish models or courted online and at gatherings of the like-bodied worry that they will lose their desirability along with their pounds.