To reiterate, long term studies on diets, show that they don't work.
I lost weight before and since my diagnosis with diabetes and since without going on a diet.
Using myself as an example, I have been low carbing since 2010, organic since 2012. My health has improved, my blood glucose control is much better, but despite not eating any cakes, biscuits, pasta, rice, pizza, puddings, other processed carbs and root veg I have gained around a kilo in weight since 2010 - not enough to need to buy bigger clothes.
But if I were in a study a kilo more than 2010 would put me in the failed diet category.
I don't believe in calorie restricted diets. My mother is a serial dieter even though currently size 8/10 and I've watched her on diet after diet my whole life and all it did for her was give her early onset osteoporosis and obsessions about calories and putting on even 2lbs. So she also would be considered a diet failure because her weight has been anywhere between 8 stones and 15 stones.
Most people, regardless of diabetes status, fail to maintain weight loss on or after diets. If your weight declines, your body tries to increase insulin levels to hang on to your fat. Before exogenous insulin, Type 1s always died, because no matter how many calories they were fed, they couldn't hold on to the fat.
I don't see low carbing as anything but a tool to reduce the type of food which my body has major problems in processing. I'm not restricting calories or non - starchy vegetables. Mine isn't a very high fat or very high protein interpretation of low carb, either.
I was reading a University of Sydney PhD thesis from 2014 yesterday, and though I've not finished reading it yet, it shows that the Type 2s studied were putting out 142% more insulin than people without diabetes, in response to protein + glucose meals.
Dr Jason Fung says that high blood glucose levels are a symptom of diabetes and controlling the BG is like treating a fever caused by infection, without treating the infection. At this point, I don't think we entirely know why the insulin goes haywire and produces Type 2 and weird levels. It could be due to a gene. Not all obese people get diabetes and not all Type 2s are obese.
Professor Taylor and Dr Fung can rave about the Newcastle Diet and Intermittent Fasting and short-term they may work. It can be shown that short-term low carb works better than low fat. Long term studies will come in and the sole one I've seen, showed that low carb was no better than low fat or calorie restriction.
So it doesn't matter how people lose weight, if they wish to lose it. We cannot trump the evolutionary survival process, long-term. Diets only seem to work, if they kick start lifestyle changes.