Hey, well done! That is a significant drop in HbA1c in just 4 weeks
The HbA1c reflects a 3 month average (a rough average) so if you keep going as you are, the improvement will be even more visible when you have been on it for the whole 3 months.
I try and suggest people to try low carbing first, before they do any low calories stuff too. There are several reasons - some (many?) people find that they gently and comfortably lose weight on Low Carb, without the hassle of counting calories too. And that can take time to kick in. At the same time, people often increase activity and sometimes gain muscle mass, which can disguise fat loss. Another reason is that people often find that their appetite reduces after a while on low carbs, which makes it much easier to lose effortlessly. I am all for effortless.
If they then add in low calorie too, then they will probably find it an easier transition than cold turkey on carbs, and a big calorie deficit at the same time.
So if you are happy that you have reached the stage where you are adjusted (appetite and happy on the reduced carbs) then it may be time to look at what you are eating. Have you really reduced the carbs enough to see maximum benefit? It can take a while to actually work out where hidden carbs are hiding. Have you increased the fats too much (it is VERY easy to overload on nuts, for example)?
Another thing to bear in mind is how
fast do you want to lose? I much prefer slow loss. I think it is far kinder on the body, and much more likely to stay off in the long run. Others want to diet quickly and then settle into maintenance. I stopped dieting like that a while back, mainly to avoid the excess baggy skin - but since that is also affected by age and hormones, as a man, you may not have to deal with that particular joy.
I think the key part of your original post is this:
So it sounds as if
something is happening. In your place I would give it more time to see exactly what that is, before you start changing what may turn out to be a winning combination.
We had one poster recently who had been losing well on LCHF, but who stalled for weeks. Got very demoralised with it. Then suddenly, for no apparent reason, the loss started again, at a rate of 1 pound a day, which went on for days and days. Obviously that isn't directly comparable to your situation, but it shows that the body can hold onto fluids and 'weight' then shed quickly, at times.
I think we often forget what a seismic shift it can be to fundamentally change our way of eating, and just need to give our bodies' time to catch up.
Hope that helps.