<<Disclaimer:  Verify this information before applying it to your situation.>>

As I remember the Aitken's diet, it would be virtually gluten free because it
required eating a high level of proteins and fats and virtually zero carbs.
 Your body goes into ketosis because you are "living off" fat and protein for
energy, something that is normally provided by carbs.  In fact, you were
supposed to buy keto sticks at a pharmacy to check your urine for ketones, an
indication that the "diet" was "working".  The drawback to the diet was that
the minute you went off of it, and started eating a normal diet, that
included carbs., you would gain the weight back.  In this day and age, with
all we know about fat, it's obviously not at all healthy...but I suppose it
was virtually free of gluten.