What vitamins should I take on Wegovy — and why it matters

Step 1 (understand why eating less can mean absorbing less

The first thing worth knowing is that Wegovy's mechanism) slowing gastric emptying and reducing appetite through GLP-1 receptor activation, is exactly what makes nutritional gaps possible. You eat less, which is the point. But micronutrients don't come in supplement form in your natural diet; they arrive bundled with the calories you're now consuming in smaller amounts.

Fat-soluble vitamins like D and K need dietary fat to absorb properly. B vitamins, including B12 and folate, are spread across animal proteins, leafy greens and fortified foods, all things that can shrink in portion size. This isn't a crisis. It's a known pattern worth managing proactively, and the NHS medicines information for semaglutide notes that treatment should sit alongside a reduced-calorie diet and increased activity, ideally with dietary support.

If you're wondering whether Wegovy is the right treatment option for you in the first place, our overview of who Wegovy suits covers the eligibility picture.

Step 2 (the vitamins most worth prioritising

There is no universal vitamin protocol endorsed for Wegovy specifically) the evidence base here is more developed for post-bariatric-surgery patients. That said, clinicians in UK weight-management practice tend to focus on a consistent short list.

Vitamin D. The UK population is broadly deficient anyway, particularly through winter. PHE has for years recommended that adults consider 10 micrograms (400 IU) daily. On Wegovy, with reduced dietary fat intake, maintaining adequate D status is sensible. Your GP can check your serum level with a simple blood test.

Vitamin B12. Found mainly in meat, fish, eggs and dairy. If your portions of these shrink markedly, B12 intake can fall. Deficiency develops slowly (months rather than weeks) but the consequences (nerve function, energy, mood) are meaningful. Worth monitoring, especially if you already eat a low-meat or plant-based diet.

Folate (B9). Leafy greens, legumes and fortified foods are the main sources. Important for everyone; especially so if there is any possibility of pregnancy, since Wegovy is not recommended in pregnancy and a conversation about contraception and preconception planning should happen with your prescriber before you stop treatment.

Iron. Less commonly discussed but worth noting for people who menstruate or who significantly reduce red meat intake. Fatigue attributed to GLP-1 side effects is sometimes iron-related.

A standard supermarket multivitamin covers this ground adequately for most people and costs very little. It is not a substitute for a clinical review of your bloods, but it is a reasonable precaution while you arrange one.

Step 3, protein, hydration and what sits alongside the vitamins

This comes up often enough with our prescribers that it belongs here. When you're losing weight on semaglutide, a portion of that loss can be lean muscle mass, particularly if protein intake is low and resistance exercise is absent. Protecting muscle matters for metabolic health, strength and long-term weight maintenance.

UK dietary reference values suggest roughly 0.75g of protein per kilogram of body weight per day for the general adult population. Many clinicians working in weight management suggest aiming closer to 1–1.2g per kilogram during active weight loss. Spreading that across meals is easier when appetite is suppressed.

Hydration is the other practical factor. Nausea and reduced thirst on semaglutide can mean people drink less; dehydration compounds fatigue and can make side effects feel worse. Aiming for around 1.5–2 litres of fluid per day is a reasonable baseline, plain water, herbal teas, low-calorie drinks all count.

For a fuller look at what nutritional support looks like in practice, this guide to vitamins when on Wegovy goes deeper on individual nutrients. And if you want to compare the evidence on vitamin needs across different weight-loss medicines, our Wegovy and vitamins page covers the broader context.

Step 4, getting your nutritional needs properly assessed

The honest position is this: the best way to know which vitamins you personally need on semaglutide is a blood test. A full metabolic panel from your GP (including vitamin D, B12, folate, ferritin and a full blood count) takes one appointment and gives you actual numbers rather than educated guesses.

If your GP is not yet aware you're on Wegovy, telling them is worthwhile. UK guidance on weight-management injections supports GP notification, and a clinician who knows your treatment can give much more targeted advice on supplementation. The NHS England guidance on weight-management injections covers the wraparound support that should sit alongside treatment, including dietary and physical activity advice.

It's entirely reasonable to feel a bit overwhelmed by this at the start, you're managing a new injection routine, adjusting to side effects, and now someone is suggesting you audit your micronutrients too. One thing at a time. A daily multivitamin is an easy first step; a conversation with your GP about blood tests is the proper one.

If sleep is another thing you're managing alongside treatment, some people on semaglutide report disrupted rest, our page on Wegovy and insomnia looks at what's known. For a broader picture of the treatment itself, the semaglutide overview covers mechanism, licensing and the clinical evidence in full.

Private treatment costs are a fair question too. This breakdown of Wegovy pricing in the UK explains what the market looks like honestly.

If you'd like your nutritional needs considered alongside your clinical suitability for treatment, speak to our prescribers, the consultation is free and reviewed the same day by a real clinician.