I am considered overweight because a doctor calculated my BMI and said I'm two kilos over where I should be. BMI is a the ratio between weight and height. I think it's kind of stupid but it got me labeled as overweight.

It is my understanding that BMI is pretty much useless for the individual to know, but it is a valuable aggregate statistic. So it makes sense for the doctor to record your BMI for the national database, but you obviously have much better information and metrics to use on yourself.

My understanding was that BMI was pretty accurate for most people and only gets out of whack for more muscular people.

BMI is a standard that applies to both women and men, so if your body fat is < ~15% you are out of the norms and BMI no longer directly applies.

It also applies less as you pass 2 standard deviations of average height.

So, if you are 6'1 and have bulky shoulders and no belly, your bmi should actually be on the high side. Warning signs are when you see ribs or when you can pinch belly fat.