B12Beth said:

A sustained drop to 1,100 or 1,200 calories reliably under-delivers a predictable set: B12, vitamin D, iron, folate, zinc and magnesium.

Vitamin D levels and micronutrients: an often-overlooked connection. Obese individuals store vitamin D in adipose tissue, making it less bioavailable. As you lose fat, vitamin D can actually increase WITHOUT supplementation.

My trajectory: Baseline 18 ng/mL → Month 6 (with supplement) 42 ng/mL → Month 12 48 ng/mL. Target is 40-60 ng/mL. Adequate vitamin D supports immune function, bone health, and mood — all relevant during weight loss.

A narrower follow-up, since the general answer is now clear:

Was that from a primary source or from a summary of one?

jason_paloalto said:

Vitamin D levels and micronutrients: an often-overlooked connection.

Coming at jason_paloalto’s question from a different direction. Start from the measurement rather than the conclusion. Almost every disagreement here turns out to be two people measuring different things and comparing the numbers anyway.

OP back with an update, since a thread like this is useless without one.

Late follow-up. I did not do what was suggested, I did something adjacent, and it worked; posting the difference in case it matters to somebody.

LindaRN_retired said:

Start from the measurement rather than the conclusion.

No disagreement, though it depends on where somebody is starting from, and this thread has been assuming a starting point nobody stated.