what is the difference between bmi and body fat ratio

Well today I weigh in at 285.7. When I went to the seminar I was 317.5. Jan and Feb I lost 13 lbs each and March only 5.8 lbs. My bmi went down to 46 something and I think my body fat ratio was 49.9 percent. She said the body fat ratio should be less then the bmi and mine is very high. So what is the difference between them and why am I not losing any body fat ratio but losing weight (pounds) and bmi. This makes no sense to me. I see the pscyhologist today she has 2 things that she is worried about for me one is support and the other is exerise. She said that I don't need to go back to her unless I start stress eating again. So tomorrow I go see the phsyical therapist and on April 13 the dietician again.

A BMI is only the relationship between how much you weigh and how tall you are.  A very muscled body builder and a fat person can have the same BMI.  the body fat ratio measures athe amount of body fat.  So the muscle builder could have a lower body fat ratio than the fat person and still have the same BMI.  Daisy