Got a date tonight, she looks curvier in the pictures rather than fat but I don't know.
What is the difference between curvy and fat? 
A curvy woman still has a narrow waist ;-). But we need several dimensions to capture this distinction. My proposal is:
Dimension 1: Fat percentage
Dimension 2: Waist circumference
Dimension 3: Ass size and shape
Dimension 4: Boob size and shape ;-)
Dimension 5: Skin tautness (loose skin etc...)
Dimension 6: Shoulder width
Actually, to fully capture curvy vs fat, you need to consider the whole as a sum of the values of these dimensions ;-). Then we need definitions of "skinny fat", "curvy" fat etc...
NN