Dietary modifications help some patients in such cases. Your doc is the best judge of your situation. Whipple's procedure is a big surgery, as you already know. In some patients after removing gallbladder, the bile presented to gut acts as irritant and causes diarrhea. Such diarrhea due to gallbladder removal responds to medications such as Questran that is a bile salt binding resin.
Dietary modifications help some patients in such cases.
Your doc is the best judge of your situation.