A little bit confused.

I am not sure what options you have over there to find out your body composition (what % of you is fat and what % of you is muscle). Tape and caliper measurements are one option. DXA (or DEXA) scans are another. Bodypod and other methods are also available.

I regret not doing a DXA scan right away, but I only pay about half of what I see bodyscanuk charges : - )

Anyway: knowing your lean muscle mass would allow you to further dial in your caloric burn. And it would give you a starting point to strive to maintain.

As you lose weight you will lose fat and non fat mass. I would suspect the whole point is to maximize one and minimize the other!

And the strategy to minimize lean muscle mass loss is: less aggressive deficits, eat lots of protein (up to 0.8g per lb of your lean body mass), lift heavy, don't do excessive cardio.

Having said that, the more excess fat you have the easier it is to lose fat only.

And being in the 'enviable" position of having lots of it I haven't personally lifted anything heavy as of yet, so others will best advise you on that.

As you keep losing weight and as you discover that it is easier to move around and do things I am sure that your goals will adjust. Maybe you will decide to do different activities, or to target something other than pure weight loss as your end goal.

But, as you make various eating or exercise decisions ask yourself whether you are making choices that you can sustain over the next 10 or 15 years. Because if the answer is that you don't see yourself continuing to do whatever... then what happens when you stop doing it?

That's it for me for now in terms of sage advise : -)
I am almost asleep in my chair 'cause it is 2:40am... so good morning to you : - )