One other possibility is to add a bit of ghee to your diet. You can buy it at an Indian grocery store or make it easily. Don't get the vegetable type, make sure it is cow butter.
Put a pound of unsalted butter in an uncovered pot and turn the heat to low. 1/4 of the way around the dial on the low side and let it very gradually heat up. The oil will float to the top and water and milk solids will settle to the bottom. When the oil turns a golden yellow (and smells wonderful BTW) it is ready. Turn the heat off and get a clean bottle, maybe a Mason Jar if you have one and pour it in. The crusty stuff at the top is delicious BTW. The oil part is the ghee. Do not use the watery stuff at the bottom of the pot as it will cause the ghee to go bad quickly. Some people filter it through a cheesecloth but I think that is overkill.
This will not increase your body weight unless you have a serious weight problem and will not affect your bad cholesterol levels. However limit the intake of ghee to say a couple of teaspoons a day if you have a serious weight or cholesterol issue or are just a worryer.
I agree with the other posters (Dewey, Seedy and Turbo) about the whey protein. I suspect that it acts like a sponge in your system, soaking up the water and drying out the GI tact. Soy products can tend to be a bit dry. You can make the whey by the way (pun intended) but it's a bit of work, like making bread. Get a recipe on making soy milk or tofu. However like Carbonddale said Beano, (although a bit of a pain, 1 tablet per bite) will help.
The ghee acts in a similar way to the water. It softens and lubricates the GI tract and aids in the digestion, assimilation of nutrients and helps it slide through.