But weight by itself (and BMI) are fairly crude measures. You could be 6' tall, be a muscular 210 lbs with a body fat of 10% and be classed as obese. The next level of the "onion" is body composition (fancy scales do this, but not that well). Then you're getting dexa scans....and there are probably other levels after that. I think I'd rather know if my weight and body fat % are going up or down, rather than their absolute value.