you have said:

1. You don't trust the National Weight Registry because it relies on self report

2. ALL diet research relies on self report.

Now, all else being equal (all keto and calorie reduction research, including the National Weight Registry) which is easier:

Keto + ALL lo-carb research: which requires information regarding:

(a) amount of food you eat

(b) type of food you eat

(c) both "a" and "b" for all instances during each day, and if the research is long term, as you regularly advocate, then just one year of research involves self-reports of AT LEAST several thousand data points

OR

National Weight Registry:

(1) initial weight

(2) final weight

if you don't trust self report, the research you rely on for your claims is obviously far less reliable than the NWR research, which shows, in fact, that thousands of people DO succeed in losing weight based on caloric reduction and wise physical activity.

You can't have it both ways. Have you ever conducted research? I can tell you, the research I conducted requiring hundreds of data points was FAR more complex than that requiring only a few data points. And my research was far far simpler than any diet studies. .