Once There Were It Girls. Now There Are Eat Girls.

Riotous hues are no longer expected just on the runway, but also on the plate. “I want it to look like the rainbow,” the English model and cook Tess Ward has said of her average meal.

Not because of the toddler dictum “eat your colors” appropriated by health-conscious grown-ups, but to render it fit for Instagram, where her feed has been filled of late with photographs of a red and yellow tomato salad; a luridly magenta beetroot curry; and an icy green cantaloupe melon with a snow-like dusting of feta. (Woe betide cozy old gray porridge which now must be gussied up with seeds and fruits and presented in wholesome “bowls.”)

“You don’t have to be perfect; you don’t have to be someone who only has green smoothies for breakfast,” Ms. Ward last year told a crowd of mostly female fans at an event for Sweaty Betty, the active-wear company. Privately she has referred to herself as Messy Tessie. “Give me the biscuits!”

“You are so refreshing,” the presenter said, “so refreshing.”

The fashion industry has long adopted artists and musicians but has been slower to warm to food personalities; Ms. Ward, 28, seems to satisfy its bottomless hunger for novelty and kinetic motion. She has been pictured in a protective crouch in the passenger seat of the heartthrob singer Harry Styles’s car, crossed the Atlantic to oversee dinners for brands like Chloé and Mulberry, and worked as “brand ambassador” for Dolce & Gabbana and Michael Kors — no cooking required.

This September Ms. Ward is sitting out the New York shows, traveling to among other places Lake Como, Italy, where she posed in underwear on her hotel bed (why not), and Greece. Toward fashion week’s rituals she is irreverent if not indifferent.

“All the people outside — it’s sort of weird,” she said of the street-style hordes. “It attracts a very strange crowd.” She doesn’t like fashion criticism either. “The element of reviewing someone’s creation! I think you can select the pieces that serve you well. I don’t think you have to critique them so much.”

Saucily named “The Naked Diet” and published in 2015, Ms. Ward’s first cookbook itself received mixed reviews. “I wanted to call it ‘The Natural Pantry,’” she said with some regret. “It was a playful way of saying you don’t really have to complicate your food to make it colorful and delicious.”

The sequel is tentatively titled “Filthy Healthy Cravings”: a compromise, perhaps, between recent salad–centric compendia and the permissive indulgence of Chrissy Teigen’s cookbooks.

Born in Tooting, South London, Ms. Ward has paid unusual attention to food since she was a baby, when at her christening party, she said, “I was passed around by the guests and only interested in the scones in their hands and the champagne in their glasses.” She studied art history at the University of Leeds and cooking at Le Cordon Bleu in Paris. “But the techniques they teach you are just dated and not very exciting. Very old-school French: way too much butter, quenelles and you make mushroom duxelles and you learn how to chop brunoise, julienne in everything, how to, like, sieve. Mousses. Oh my God, like, dealing with aspic. It feels like a lifetime ago now.”

She prefers the more casual approach of current British author-chefs like Yotam Ottolenghi and Nigel Slater. “He is very sensual in his writing, very inviting in the way he talks about food, and it’s very much about pleasure,” she said of Mr. Slater. “You feel very caressed when you read him.”

Yet Ms. Ward is ready to shed her come-hither nickname, the Yes Chef. “It started as a little bit of a joke because ‘yes, chef’ is what you say in a kitchen taking an order,” she said. “I’m actually trying to phase it out because it’s not really on point for what I’m doing. I’m Tess and I cook. That’s enough now, you know?”