Read the primary source rather than the write-up and the two do not agree, so here is what is actually in it.
A sustained drop to 1,100 or 1,200 calories reliably under-delivers a predictable set: B12, vitamin D, iron, folate, zinc and magnesium. Two of those are worth testing rather than guessing because the tests are cheap and the symptoms overlap with everything else — ferritin and B12. The rest a decent multivitamin covers, and there is no benefit in megadosing any of them.
Where I think it is weakest: the comparator does most of the work in how this gets reported, and it is not the comparator most people think they are citing.
The bit I cannot resolve on my own is which deficiencies actually show up when intake drops this far, and which are worth testing rather than supplementing blind. Tell me what I have not thought of.
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.
TomTeleRx 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.
Blood count monitoring for micronutrients: my doctor noticed my MCV (mean corpuscular volume) trending up at month 6: 91 → 96 fL. This flagged potential B12 or folate deficiency.
Sure enough, B12 had dropped from 620 to 340 pg/mL. Started B12 injections monthly and MCV normalized within 2 months. GLP-1 agonists can impair B12 absorption — this is a real clinical concern that deserves routine monitoring.
TomTeleRx 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 and mineral labs to check while on micronutrients — my doctor orders these quarterly:
- B12: Can drop due to reduced GI absorption. Mine went from 650 to 380 — now supplementing.
- Iron/Ferritin: Reduced food intake = reduced iron. Ferritin dropped from 71 to 28. Supplementing.
- Vitamin D: Was already low (22 ng/mL), now taking 5000 IU daily.
- Folate: Stable, no issues.
- Zinc: Slightly low, added a multivitamin with zinc.
Nutritional deficiencies are a real risk when you're eating significantly less. Don't skip your labs!
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View ResultsDr.SurgeonPGH said:Vitamin and mineral labs to check while on micronutrients — my doctor orders these quarterly: B12: Can drop due to reduced GI absorption.
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.