Jessamyn Stanley just proved again why she's one of our favorite trainers and body-positive advocates. In a recent interview with Runway Riot, the Shorty Award-winning yoga teacher dismantled the belief that you have to be thin to be healthy."Basically, I'm the unicorn of health," Stanley told the website. "A healthy fat person is an oxymoron to most people. People don't realize that they can't tell anything about someone else's health by just looking at them."She's right — you can be overweight and healthy, just like you can be thin and unhealthy."If you’re overweight or slightly obese but fit and metabolically healthy — normal blood pressure, normal cholesterol levels, normal blood sugar — then it’s hard in that situation to show that being thinner would make you even healthier," Carl Lavie, MD, told us earlier this year.And while the body mass index (BMI) has long been used to judge health, it's not always considered the most accurate benchmark . Though it's used to classify people as being "normal" weight versus underweight, overweight, obese, and so on, it's "not the whole story for any individual,” said Mitchell Lazar , MD, PhD, at the University of Pennsylvania, back in May.Simply put: Your health has everything to do with how you treat your body, rather than the size of your body.As Stanley told Runway Riot, "We focus a lot on the outside. For so long, we've been fed this idea that how slender you are of a person lets people know how fit you are."