They don't work alone for a lot of people. With proper measurements and a consultant or dietitian, knowing your BMI could be very helpful when trying to loose weight. But calculating it alone does not give an accurate score of how 'fat' a person is.
I find knowing my BMI helpful, but only because I know how to use the information, and I also know all of my measurements. I am on a strict training program at the moment, so being frequently weighed for my BMI helps me (among a lot of other things) know what I am doing right and wrong in my training.
Yes and no. I think it can be a helpful guide. Its especially good for telling you if you are underweight. However, it doesnt take into account things like lean muscle mass. Therefore, it is often misleading, tellling people they are overweight or obese, when infact they have very little body fat and are very healthy. So I think its useful, but it should be used alongside other things, like body measurements, and fat percentage.
I'm not too sure. Obviously you're more cautious of the things you take in if your BMI is at an unhealthy level, but I don't think most people even know what their BMI is or what risks are unless it's calculated in some way for them and they are told about it. In most cases, knowing your weight and calorie intake would have more of an impact, in my opinion.
yes i just lost about 10% of my bmi and i liike that hahaha makes me feel healthy