Pi

Mathematician: Pi is the ratio of the circumference of a circle to its diameter.
Engineer: Pi is about 22/7.
Physicist: Pi is 3.14159 plus or minus 0.000005
Computer Programmer: Pi is 3.141592653589 in double precision.
Nutritionist: You one track math-minded fellows, Pie is a healthy and delicious dessert!

I found this on Engineer, Physicist, Mathematician (EPM) jokes.

Whispers: Where are these nutritionist that believe with all their heart pie is healthy?