At passport control in Istanbul last month, I watched a border officer look at my passport, then at my face, then back at my passport. His eyebrows knit together. He called over a colleague. Then another. Within seconds, I had a small panel of Turkish officials studying the seven-year-old photo in my passport and comparing it to the person standing in front of them: me, but 88 pounds lighter than I’d been when the picture was taken.

My weight loss had been gradual, over three and a half years, and achieved without GLP-1 medication. But it was still enough to make me look like a different version of myself in that little blue booklet. The exchange lasted only a minute or two, but it left me wondering: If a slow transformation could raise questions, what happens when someone’s appearance changes faster?