A BMI of 25+ seems to be commonly accepted as overweight in most part of the world, at least in the medical sense. Whether it looks overweight or not is cultural. But you're right, very muscular persons are heavier and BMI isn't a good measure in that case, and it's not necessarily unhealthy if you don't have other risk factors.
> For people who are considered obese (BMI greater than or equal to 30) or those who are overweight (BMI of 25 to 29.9) and have two or more risk factors, it is recommended that you lose weight.
> For people who are considered obese (BMI greater than or equal to 30) or those who are overweight (BMI of 25 to 29.9) and have two or more risk factors, it is recommended that you lose weight.
https://www.nhlbi.nih.gov/health/educational/lose_wt/risk.ht...