Story highlights Chris Sullivan wears a fat suit on "This Is Us"

Co-star says he was best for the job

(CNN) Chris Sullivan may be one of the first actors body-shamed for not being big enough.

The "This Is Us" star has faced criticism for wearing a fat suit on the show.

His co-star Chrissy Metz defended the decision Thursday night on Bravo's "Watch What Happens Live with Andy Cohen."

"We tested a lot of gentlemen who were bigger, and I get it, like people think the authenticity is kind of ruined by that," Metz said. "But Chris has been heavier, so I think he understands the plight of being overweight."

Metz and Sullivan play love interests Kate Pearson and Toby Damon on the popular NBC drama.

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