The idea is to throw the scale away. You know, the scale that you step on in the morning, after your workout, and before you go to bed all the while wondering, how you gained and lost weight throughout the day. Body weight is used in some calculations but it is not used as much as it was. Height and weight tables are useless for anyone, except insurance companies who don't have anything else to go on. Body composition or body fat has taken over as a better determination of risk and healthy lifestyle than body weight.
Body composition is the difference between fat mass and lean mass.
Some might say she needs to lose some weight. Some would say she's pretty slim and in good shape. The 170 lb female is a shot putter trying out for the Olympic team. It appears she's got a lot of muscle and lean tissue. Yes it is.