I don't want to sound like 'that guy' but while BMI is important, it doesn't consider fat/muscle ratio, so I'd use body fat percentage as a good indicator, anything between 8-15% is great, while 15-20 is good.
In regards to the conversation above whether you can lose fat and gain muscle, yes, as long as you have a ~20% calorie deficit and get your required proteins, there is no reason for it not to, many MANY people do it.