GLP-1 Nutrient Deficiency: The Hidden Cost of Weight Loss Drugs in the UK
The UK is in the middle of the largest pharmaceutical adoption event since the contraceptive pill. By the end of 2026, somewhere between 500,000 and 1 million UK adults will be on a GLP-1 drug for weight loss — Mounjaro, Wegovy, Ozempic.
The drugs work. They also create a silent secondary problem that the prescribing services aren't telling you about: nutrient deficiency.
This isn't a reason to stop the drug. It's a reason to do the one thing your prescriber should have told you to do: supplement properly.
What the research shows
A 2024 analysis published via Harvard Health documented sharp increases in nutrient deficiency among GLP-1 users at 12 months:
- Vitamin D — 49% higher risk of deficiency
- Vitamin B12 — significantly elevated risk
- Iron — elevated risk, especially in women
- Calcium — elevated risk
Observational data points to additional risks in B6, magnesium, zinc and selenium — secondary nutrients that show up most in calorie-restricted diets.
Why this is happening
GLP-1 drugs work by suppressing appetite and slowing gastric emptying. People typically eat 25–35% less food. That's by design — that's how the weight comes off.
But your body's daily nutrient requirement doesn't drop by 30%. Your minimum daily vitamin D doesn't go down because you ate less lunch. The deficiency is mathematical.
Three compounding factors:
- Less food in total — fewer nutrients in absolute terms.
- Less variety — GI side effects push people toward plainer, blander foods. Oily fish, leafy greens, lentils — often first things to go.
- Possible absorption issues — slowed gastric emptying may reduce nutrient extraction. Research here is still developing.
What the prescribing services aren't telling you
Mounjaro is being prescribed privately in the UK at scale through Numan, Voy, Juniper, Manual, Boots, Phlo and others. These services have done an excellent job at safe, accessible prescribing.
What they have not done — and aren't really set up to do — is the nutritional follow-up. Most people on private GLP-1 prescriptions don't get a 25(OH)D test in their first year. Most aren't told about the iron risk. None are sent a supplement plan with their first month's pen.
This isn't malice. It's a gap in how the drug is delivered.
What to do about it
1. Get tested at 3 months
Ask your GP — or your private prescriber if you have follow-ups — for:
- 25(OH)D (vitamin D)
- Serum B12
- Ferritin and full iron panel
- Magnesium (if available)
2. Supplement the documented deficiencies — not everything
Avoid the temptation to take a 20-ingredient multi. Most of what's in those is in there for marketing. You need the specific nutrients that show up depleted in the GLP-1 research, in clinically meaningful doses.
3. Eat protein-first when you can stomach food
When appetite is low, protein protects muscle mass and delivers B vitamins. Eggs, Greek yogurt, fish if it sits well, lean meats. Cake, biscuits and toast don't earn their place.
4. Take supplements with food, not first thing
Most fat-soluble vitamins (including D and K2) absorb better with a meal containing some fat. Take them with breakfast or lunch, not on an empty stomach with your morning coffee.
Where Solmate fits
We built Solmate for indoor Brits — people who don't get enough sun and need a serious daily stack rather than a marketing-led gummy. The formula was designed before GLP-1s went mainstream, but it happens to cover most of the documented deficiencies:
- Vitamin D3 — 1,000 IU
- Vitamin K2 (MK-7) — for calcium routing
- B2, B6, B12 — energy and mood
- Magnesium — sleep and cramps
- Zinc and selenium — immunity
- Saffron extract — for mood
The one thing we don't cover is iron. Iron supplementation should always be dose-matched to a blood test result, so we leave it out by design.
See Solmate's full ingredient breakdown →
This article is for information only. Solmate is a food supplement, not a treatment for nutrient deficiency. If you're on a GLP-1 or any other prescribed medication, please talk to your GP or prescriber before adding supplements.
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