The original protocol by Dr. Simeons dictated to use to not use any oils, however, in very small amounts, I have not seem them to affect anything.
Keep in mind that there is a small amount of fat in the lean beef that is allowed on the diet and in chicken breast, so while we are definitely avoiding as much fat/oils as possible during the program (if you’re following one of the more traditional hCG protocols), a few drops of essential oils doesn’t seem to be much of an issue.
One hCGer told me they put 1-2 drops of essential oil to make their own P2 soda and they lost fine.
I also had a question about using essential oils in a diffuser which I answered as well.