That's just a nice way of saying that fat takes up a lot more space, pound for pound. :laughings Obese people can be strong too. They can exercise, get stronger, and still be obese. I am a proponent of BMI. I get the whole muscle weighs more/BMI isn't accurate rubbish. That argument only applies if you can see your six pack or are a competition level lifter. In other words, someone who obviously doesn't need to lose fat in the first place. BMI is very relevant and therefore weight is as well.