Understanding Tanita: Why are there different readings for male compared with female?

Men are built differently from women. Genetically, men's bodies are adapted to develop and hold muscle tissue - they are designed to be hunters. A woman's body is designed to hold fat for child bearing. A man who is exactly the same height and weight as a woman will have more muscle and less fat than she does. (That is why men need more calories in their diet than women.) The calculation that the body fat monitor performs is adjusted to take account of this.