Fossa wrote:I really loathe the BMI system since muscle is so much denser than fat. My BMI has gone up steadily as I've gotten in better shape, and I still want to lose a little fat and gain a little muscle.
BMI has it's problems, and isn't one-size-fits-all, but remains a useful indicator for many people.
Among people who aren't exercising much, or whose exercise is skewed in particular directions (ie how much aerobic vs anaerobic), it's useful since proportional muscle gain is slight compared to weight loss. One way or another I average about 2-3 hours of exercise a day, but mostly flexibility & cardio so my BMI isn't too out of whack and I know that the difference dosn't really matter, very little fat but more muscle than "average" (dancers thighs
all slow twitch muscle). Conversely, if someone's focused on anaerobic then, assuming they're already reasonably fit, their BMI will be relatively high.
A well-balanced aero+anaerobic programme for someone overweight wanting to become fitter will result in them gaining muscle, but the weight-loss will be far more significant, so their BMI will go down. The limited awareness of the limitations of BMI causes problems though; I quite often see obviously unfit people exclaiming that their BMI is okay since a lot of it is muscle mass, which is obviously nonsense.
BMI is broken for the people who don't need it, but fine for most of those that do.