I had a look at it but it seemed rather extreme to me. Instead I tried cutting out snacks and a lot of carbs, and eating three meals a day in an 8 hour widow. I lost 2 lbs per week for a few months, then slowed down, but eventually my fasting blood sugar came down to normal without medication. I was never particularly hungry! I then stopped the calorie restriction by increasing fat and protein, and my weight did not rebound.
So, the NHS diet is not the only way, and I don't think it is the best, at least not for me.