Hello Mr. Mel,
I, like you, seem to need to stay around 20 carbs a day to keep my weight coming off. In Atkins New Diet Rev. book, he says in Chpt 13 that you can safely do induction for 6 months or more and gives a case study of a patient who stuck to 20 carbs for almost 2 years to lose her weight. A lot depends on you and your body's metabolic resistance. For me, I am not on induction only foods, but I have found I must stay at no more than 20 carbs a day to keep losing weight and I want to be a good loser!
Good luck.
Marie