Trinian Taylor, a 52-year-old car dealer, pushed his cart through the aisles of a supermarket as I pretended not to follow him. It was a bright August day in Northern California, and I had come to the store to meet Emily Auerbach, a relationship manager at Mattson, a food-innovation firm that creates products for the country’s largest food and beverage companies: McDonald’s and White Castle, PepsiCo and Hostess. Auerbach was trying to understand the shopping behaviour of Ozempic users, and Taylor was one of her case studies. She instructed me to stay as close as I could without influencing his route around the store. In her experience of shop-alongs, too much space, or taking photos, would be a red flag for the supermarket higher-ups, who might figure out we were not here to shop.

Auerbach watched in silence as Taylor, who was earning $US150 in exchange for being tailed, propelled his cart through snack aisles scattered with products from Mattson’s clients. He took us straight past the Doritos and the Hostess HoHos snack cakes, without a side glance at the Oreos or the Cheetos. We rushed past the Pop-Tarts and the Hershey’s Kisses, the Lucky Charms and the Lay’s – they all barely registered.