I have heard people say that keto gives you more energy, but would be so difficult to sustain for me. The issue I would have with maintaining that level of low carb is getting enough calories, not eating meat. A load of vegetables is nowhere near enough, I only just get enough calories now and that's with eating a lot of nuts. I also need to get my cholesterol down a bit and don't want statins so increasing saturated fat won't work.
I'm pretty sure now it's down to depletion of glycogen stores, I have read some about this. If you only eat enough carbs to just cope with every day activities you never build up stores so fatigue and muscle weakness. It improves when I eat more carbs so I think that is what I have to do, just try and find the minimum I can get away with. Thyroid was fine. Strangely my response to carbs seems to be improving 8 months in, I can have more than a few months ago and don't need to exercise every time. I thought that was impossible with T1, not complaining but odd, still no insulin or any medications.