The side of Vicki VanDeCarr’s tote bag reads, “Only kale can save us now.”

In Marshall, a growing number of residents believe that slogan is not far from the truth. Barbecue and chicken-fried steak are a way of life in this corner of East Texas; so are obesity, diabetes, cancer and heart disease. But because of the mayor, Marshall is becoming known as a stop on the national vegan speaking circuit and a small city where people who eschew animal products can order in restaurants.

Ms. VanDeCarr, 52, came to Marshall from nearby Beckville last weekend for the New Year, New You Health Fest, which promotes a vegan diet. In its third year, the event attracted more than 400 people from 17 states and three countries. The agenda included exercise classes, cooking demonstrations and lectures by vegan celebrities like the runner Scott Jurek and the cooking instructor and author Colleen Patrick-Goudreau.

One day last year, Ms. VanDeCarr’s Zumba instructor invited her for vegan snacks after class and sent her home with a copy of the 2011 film documentary “Forks Over Knives.”

“Before, I thought going vegan was like eating cardboard and hugging a tree,” Ms. VanDeCarr said. “After eating some of her food, I was like, ‘Man, it tastes really good.’ ” She watched the documentary, which helped convince her that a plant-based diet could help her avoid some of the health problems plaguing other members of her family. Since then, Ms. VanDeCarr has helped her daughter, son-in-law, mother, mother-in-law, father-in-law and four grandchildren convert to what she calls a plant-based, whole foods diet. Although the diet promoted in Marshall excludes animal products, most refer to it that way, avoiding the term vegan. “Vegan” calls to mind what you cannot eat, while “plant-based, whole foods” emphasizes what you can, said Shannon Johnson, the Zumba instructor who converted Ms. VanDeCarr.