I have also been on the diet for three weeks.
The first thing I noticed was a feeling akin to a new pair of eyeglasses — my head felt clearer. The second thing was increased energy. I have had three days in 3 weeks when I did not get tired during the day, an experience I have not had in 14 years! The last improvement has been in the quality of my sleep. I do not wake up as often and I no longer need nine hours a night. Seven and one-half or eight is enough.
I have stopped soy, dairy and gluten and am close to nine cups of veggies, though the sulfur category is a bit of a challenge. I am not entirely off sugar, though I am eating way less of it and substitute brown rice syrup when I can.
I feel great and am so happy with these changes. The biggest challenge will be maintaining the diet when traveling.