Hi Steve and welcome! It's interesting that you're looking for the low-carb diet drop-out rate as I myself have been looking for the Weight Watchers' drop-out rate. It's of personal interest; so far, no luck but I'll keep trying.

I recalled reading a statistic in Gary Taubes' Good Calories, Bad Calories that said something along the lines of 1 in 2 will have success with restricted carb dieting in comparison to the 1 in 50 who will have success with low-cal dieting. I've been able to find the comment on p. 339-40 in the context of the experience of Bistrian & Blackburn [who are in Pagli ('85)]. B&B saw more success with patients on a restricted carb diet of fat and protein with calories restricted to 650-800 than when those same patients were given an extra 400 calories for carbohydrate. The oddest thing was, the low-carb 800 calories folk did not experience the hunger that the 1200 calories "balanced diet" folk did.

There are more citations leading up to this particular little passage. Starting on 337, a few are Hanssen ('36), B. Sjovill ('57), T. Silverstone ('63), L. Pena ('79), and R. Kemp ('63 & '73). GCBC contains 40+ pages of citations and a 50+ page bibliography; there's also chapters devoted to diabetes.

Taubes' credentials are degrees and advanced degrees in physics, engineering, and journalism from two Ivys and that lowly hillbilly place in Palo Alto (lol, I'm sure you know the story of how Leland Stanford Jr. University came into existence).

Good luck with your research!