Custom User Fields perform calculation?

Hi there,

First of all I'm an XenForo convert from the dark side which is vBulletin :)

I would like to know if it would be possible to perform a calculation of two custom user fields? For example:

User Fields:
Starting Weight
Current Weight

Calculations I'd like to perform:
Lost so far: startingweight - currentweight
Weight to lose: goal - currentweight

Is this at all possible?