Well shit, my BMI is 35. And I've got a pair of stents in my ticker. OTOH I'm doing crossfit 3x/week. And can dead lift over 300# so I feel like I'm getting better. ALso, I'm built like a fireplug, so probably not fat as just big. BMI is a shitty measure.
Those scales use electrical resistance as a procy measure of water density, a proxy of muscle to fat ratio. It's a tenuous link and isn't all that accurate. If you can afford the $100, go get a DEX scan.