Don't worry about the 3.5 weight gain; it sounds like a bit of water weight which will dissipate shortly. Many times hidden food allergies (like wheat, sugar, milk - all possible ingredients in the pumpkin pie) can cause that.
With regard to your trip to Japan, just stick with cooked fish, seaweeds, veggies and 1/2 cup rice per day. I wonder if you could simply take Body Protein in a large Ziploc?
I do all the time.
Good luck and Enjoy your trip. If you can at least take the Fat Flush Kit supplements with you, that would be great and keep you slim and trim with a level blood sugar
