The whole situation is unreal. My daughter is a swimmer too! She is like a brick wall because she is all muscle. Her BMI was normal on WiiFit. What I find to be a shame is how our schools calculate BMI. They base it on age and weight. They don't even look at height! They sent home a note telling me that my daughter was overweight. I started cracking up hysterically. I showed her the note, shared with her the evils of the improperly calculated stupidity of our school system. (I think a toothpick would have more width than she does.) Personally, we both had a great chuckle. (Darn, maybe I should have sued our school for stupidity! Another missed opportunity!)
If you have a lot of muscle mass due to hardcore sports like swimming or cross country, explain to people that the weight is based on the average couch potato!
That is all that it takes. If people are still feeling down about themselves then they should go see their doctor. People need to learn to have a sense of humor. All these charts are just statistics and people need to understand that there are exceptions to baseline statistics. In other words, statistics are not perfect so move on with your life.