Many many years ago, Dr. Mike Eades had a plan called Fast so Thin. It was 3 shakes plus a small meal each day (mainly salad as I remember). Many folks lost really well on it but as with most strict diets, many people gained back what they had lost.
The interesting thing to me about the Newcastle plan is most folks kept off the weight. I imagine that is due to on-going support and monitoring.
I read Turtles "experiment" and he apparently went lower carb, and a sort of IF plan, which I think should have been better but apparently wasn't as he couldn't stay with it.
I know I'm probably the odd man out on this forum, but to me 60 - 70 grams of whole carb is low carb. That would equate to about 40 - 50 ECC. Definitely not ketogenic, but still low carb.

At any rate, it appears that a combination of restricting calories, carbs and combined with fasting is one of the keys to effectively manage insulin resistance.