Hi Colin, It is widely thought that any substantial weight loss whether achieved by (one of several) Bariatric Surgical procedures, or by (one of many) variations on Calorie restricted diets, or by (one of many) variations on Low Carb 'ways of Eating' , or by (one of several) types of Fasting can give good BG and BP results among other health benefits.
What is a substantial Weight Loss? This has been claimed (with some evidence) to be the greater of either 15KG, or 10% of starting body weight.
However there is some debate as to whether the key factor is the loss of weight or the reduction in intake of Carbs.
Michael Mosely's 800 Calorie 'Blood Sugar Diet' was one of 3 approaches that I considered. However because I was never (more than 2lbs overweight - a TOFI) I decided against any crash diet or any prolonged fasting. I felt (wrongly) that I didn't need to lose any weight.
I think I was lucky that being a TOFI encouraged me towards a Low Carb Way Of Eating (i.e. no calorie reduction).
I had a choice either to increase Protein or Carbs or both in order to maintain my total Calories and I did a little of both even though I describe it as LCHF.
However I continued eating 'real/minimally processed' food as I had done when I'd been persuaded to follow the government guidelines over 10 yrs earlier ( before my 3x Coronary Bypass).
What I found was that my body became 'fat adapted' and due to the higher nutrient and Calorie density of my food my stomach shrunk.
At that point I didn't always feel hungry/as hungry at some normal mealtimes. It was only then that I introduce an occasional 16:8 Intermittent Fasting (basically skipping Breakfast if not hungry). My body currently uses up my stored excess body on these occasions such that I haven't gone hungry even though I haven't had any breakfast for more than the last 5 weeks.
It is my strong belief that it is almost impossible to lose weight without reducing Insulin first, because Insulin causes high Glucose in the blood to be safely stored away as fat in fat cells so it's presence also inhibits the use of stored fat as energy. Think of a bear either bulking up ready for hibernation, or slimming down during hibernation - it makes no sense to be doing both!
There is strong evidence that crash diets reduce the Base Resting Metabolism so the body goes into starvation survival mode , when a raising of the Metabolism is what is desired in order to lose weight.
I have read that that disadvantage doesn't apply (metabolic rate doesn't drop) in fasts of several days at a time, but I have no experience of this.
So my advice to any T2D who is not morbidly obese, is to just go for a Low Carb 'Way Of Eating' until fat adapted and then experiment with whatever (fasting or calorie reduction) takes your fancy.
