As many people have mentioned above BMI's not all that good.
What's far more important is truncal fat (ie a large waist is far more significant than having a big bum/thighs/arms etc.).
Being obese in this area is far more significant, because it's as a result of intra-abdominal fat (that is fat inside the belly). This fat is more metabolically active, and is therefore far more likely to contribute towards a huge number of conditions (namely type 2 diabetes).
More realistically, again as said above, most people know when they're overweight, and if/that something ought to be done. Most people have difficulty getting/keeping the motivation.
Well that's my excuse for a raised BMI, & I'm sticking to it
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