If I've read it correctly, being overweight is "healthier" for longevity. My understanding of science is that being overweight isn't unhealthy, quite the opposite, but its closeness to obesity is the true danger. So it is healthy to be "overweight" according to BMI, but it's close to being obese, which is very unhealthy, so if you don't watch yourself, you could hurt yourself. Aiming to be in the high "normal" BMI or low "overweight" BMI is probably the most reasonable approach. But it may be more difficult for people who build muscle to tell what that is for them.