Go to a sports store that sells camping gear and buy essential bottles such as Coleman's Coleman - Bagged Essentials Bottles. Since they are none spill you can carry your olive oil salad dressing in that.
Fermented dairy such as full fat yogurt and cheese is ok and actually seems to help prevent obesity. It's not sure why that's so but it may be due to being fortified with Vitamin D
Would I be putting a grain-feed cow on a fad diet if I took it out of the feedlot and put it on pasture eating the grass nature intended?