One of the primary reasons for such a difference has to do with the sex of the person being considered. Generally, the weight of a man would differ drastically from that of a woman since a man is made up of more muscle while the woman is made up of more fat. Muscle weighs more than fat, which accounts for why the average man is heavier than the average woman.
But in addition to the body composition of the different sexes, another factor that could complicate the ideal body weight quotation is a height difference. A tall woman, for example, could weigh over one hundred and fifty pounds and still be considered healthy; while a much shorter woman of the same weight would be considered overweight. The assumption that we use for healthy and overweight in this instance is the visual acceptance of a healthy-looking woman as opposed to a pudgy woman. The same would go for a man, and even more so when comparing the weight of a woman of one height against that of a man of equal height.
Because of such prejudice in the weighing system, the body mass index (BMI for short) was devised to establish a central ground common to both sexes as well as to take into account all the factors which would influence the outcome of an ideal weight count. The body mass index, while it establishes a relationship between one’s height and one’s weight, does not take into account the differences between a man’s ideal weight and a woman’s ideal weight. This, therefore, leaves us ideally with a separate set of values to work with for both the man and the woman. Generally, though, it is understood that allowances for both weights are so small that they are considered to be negligible, and therefore most people accept a general guideline that both the man and the woman can fall into.
The relationship between one’s height and one’s body weight does make the difference in how society views that person, as was established above. By using this said factor, therefore, the common ground for all persons was established as being a somewhat complicated relationship between the body mass in kilograms (which is the body weight divided by gravity; gravity equals ten) and the height in meters. Using this common ground, the ideal body weight is considered to range between 20 and 25 kilograms per square meter while the values on either of the two extremes are underweight and overweight respectively.