They Promoted Body Positivity. Then They Lost Weight.

Tianna James used to love looking at the photographs Dronme Davis posted of herself on Instagram. Ms. Davis, a plus-size model, included pictures from her modeling campaigns alongside selfies of her stretch-marked stomach with captions like “fat belly saggy tits Sunday.”

For Ms. James, 22, Ms. Davis’s feed was a revelation. “I wanted to feel comfortable in my body, and she was like me in so many ways, so it made it easier to be myself,” Ms. James said. “If I could find this person so beautiful, and she was bigger, I could find myself beautiful, too.”

Ms. Davis gained a following through posts that criticized diet culture as she built a career as a curve model — she wore up to a size 16 or XXL — most prominently for Dôen, a California fashion brand known for floral prairie dresses typically worn by more willowy women. Her feed was a running commentary on the unrealistic expectation to conform to a thin ideal: “A flat stomach won’t change your life” and “It’s so exhausting being afraid and ashamed of parts of ur body.”

Then, over just a few months, Ms. Davis shrank.

She still posted the artsy selfies Ms. James loved, but photos of soft belly rolls were replaced by sharp cheekbones and clavicles. She continued to write in her confessional style, sharing her feelings about everything from constipation to career insecurities. But Ms. Davis stopped posting her habitual rants against fatphobia, and she didn’t explain why or how she had lost so much weight.

To Ms. James, Ms. Davis’s silence felt like a betrayal.

“It made me feel like she was being dishonest with her community,” Ms. James said. “I don’t want to say it was owed to us, but it was such a drastic change.”

The body positive movement has recently faltered in a cultural moment where thin is back in (though some argue it never really left), thanks in part to the rise of new drugs like Ozempic that are being used for weight loss. Celebrities, models and influencers like Ms. Davis who once celebrated their curves are grappling with how to discuss their smaller bodies, while their followers feel as if they’ve abandoned the causes they used to champion: encouraging people to challenge weight stigma and to accept themselves as they are.