Body Weight. There is no simple answer to the question. People are different and so the ideal weight for one person may not be ideal for another. Reasons for differences may be: · Gender: Males and females have different body shapes and sizes and their ideal weights will, therefore, be different. · Racial: People from some races are generally of a smaller build than others. · Genetic: Some families consist of people with large builds, others with smaller ones. This may be due to inherited traits affecting skeletal structure and metabolic rates. · Age is not a very helpful factor because people do not grow at a steady rate. They have periods of rapid growth followed by plateaux. · Height is also not very useful because height and weight do not necessarily move in tandem. A measure, which gained much interest is the Body-Mass Index (BMI). This is calculated as the ratio of the mass (in kilograms) divided by square of the height (in metres) and was used to define underweight, ideal weight and overweight for a given height. However, in addition to the fact that all the issues mentioned above were largely ignored, the major flaw with the BMI is that it does not differentiate between muscular mass and fatty mass. Muscles are denser than fatty tissue so a fit person will have a higher BMI than a person who is carrying a lot of fat.