FYI Virta Health trials are good proof of the pudding!
https://www.virtahealth.com/research Virta offered standard of care to US patients versus a low carb diet (both remotely and got better metabolic results all round at 1 and 3 years.
An RCT is the gold standard obviously but there are plenty of N of 1 experiments going on out there and I think these options could be more widely offered to Type 2 patients given that NICE guidelines suggest an individualised approach.
Some people prefer the simplicity of fasting, others might like the more drastic 800 kcals method (not really a similar concept IMO) and low carb is a very successful method for those looking for a permanent lifestyle solution without the need to count calories. It also works well for us type 1s! All of the above trump the current EatWell plate advice which I think is highly inappropriate for most type 2s (High Carb, Low Fat).