can anyone explain this to me?

[Jampot]

my friend and i have measured each other and she is overall about 30 inches bigger than me (using thighs,upper arms, waist, bist, hips) but only weighs a stone more than me. Another friend is much the same size as me but weighs 2 stone less than me!

muscle is heavier than fat...does that help?

Bone mass, muscle mass, fat percentage, bloating or constipation ect all cause some considerable variations in body weight. Your heavier friend may have a higher body fat than you so she is bigger for her weight as fat takes up more space.
Similarly you lighter friend could be less toned than you causing her to be lighter for her size than you.
You may also have denser bones so are heavier regardless of body fat ect.

ok thanks