Each of these attributes will be examined in turn. Unless specifically stated, the range of the attribute is from 1 to 10. The value of Size ranges in humans from about 3 to 9. An average human male has a size of 6. Human females have an average size of 5.
Size is basically a measure of how much the character weighs.
It is a contributor to the major attribute of Strength. Fitness Fitness ranges from 1 to 10, with 5 an average value. Fitness is a measure of how strong the character is, based on size. An extremely obese person might have a large Size, but a low Fitness. Fitness contributes to Strength.