Short answer first, then the reasoning. 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.

Dr.SportsMedIN 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.

Agreed, with the caveat that iron should be tested before supplementing, not after. Supplementing iron into normal stores is unpleasant at best and harmful in haemochromatosis.

adam_van said:

Six weeks of shedding, no bald patches, and a GP who told me to come back in three months.

Mine went the same way, slower. I had assumed I was the exception until I read this.

Adding the clinical framing, because it changes how the question reads.

Hair loss update related to hair shedding: I experienced noticeable shedding starting around month 3. My dermatologist confirmed it's telogen effluvium — a stress response to rapid weight loss, NOT the medication directly.

What's helping:

• Biotin 5000mcg daily
• Adequate protein (130g+/day)
• Iron and ferritin levels checked and supplemented
• Collagen peptides 20g daily
• Minoxidil 5% topical (prescribed)

The shedding slowed after 2 months and my hair is now growing back. Temporary but definitely stressful.