Supplements worth considering if you're using semaglutide for weight loss

Three weeks in: the nutrients that quietly drop when you eat less

Picture yourself a few weeks into treatment. The pen arrives in a plain box, tracked by DPD, and the weekly routine has already begun to feel ordinary. What's less obvious is what's happening to your micronutrient intake. A typical adult eating 1,200–1,500 kcal a day while on semaglutide will likely fall short of iron, vitamin D, vitamin B12, folate, calcium and magnesium without trying. These aren't theoretical concerns, they're the nutrients most commonly flagged in structured weight-loss programmes.

Vitamin D deserves particular attention in the UK, where dietary sources are limited and sunlight is unreliable for most of the year. NHS guidance on healthy weight already recommends a daily 10mcg vitamin D supplement for most adults; that advice doesn't change when you add semaglutide, but the reduced food volume makes it more important to actually follow. B12 deficiency can develop slowly and is easy to miss early, so if you've been eating significantly less meat or dairy, it's worth mentioning to your prescribing team. A practical starting point if you're thinking about what supplements to take while on Wegovy is to review the core list with those gaps in mind.

Calcium and magnesium often travel together in combined supplements, which keeps things simple. Magnesium is involved in hundreds of enzymatic processes and is frequently low in people following a calorie-restricted diet; muscle cramps sometimes flag this before a blood test does. None of this is alarming, it's just the practical consequence of eating less, and it's manageable with a little structure.

Protein: the supplement question most people forget to ask

Protein isn't glamorous, but it's arguably the most clinically significant gap for people using semaglutide for weight loss. Rapid weight loss, if protein intake is too low, draws on muscle as well as fat, and muscle loss affects metabolism, strength and long-term weight maintenance. Most adults need around 1.2–1.6g of protein per kilogram of body weight per day to preserve muscle during active weight loss; many people find hitting that target difficult when their appetite is suppressed to a fraction of its usual level.

Whole-food sources (eggs, fish, Greek yoghurt, legumes) are the first choice, partly because they come with other nutrients and partly because ultra-processed protein products are not a substitute for a balanced diet. When appetite makes whole foods hard, a simple whey or plant-based protein powder added to a smoothie or porridge can bridge the gap without requiring a large meal. This isn't a medical recommendation for any individual; your prescriber and, ideally, a registered dietitian can advise on targets that suit your starting weight and rate of loss. The supplements typically recommended alongside Wegovy often include protein support for exactly this reason.

Strength-based exercise alongside treatment helps preserve muscle too. The two (adequate protein and resistance activity) work together in a way that neither does alone. Worth knowing before you spend money on anything else.

What to be cautious about: supplements that may need timing attention

Most supplements are safe to take alongside semaglutide injection without special timing concerns. Two exceptions are worth knowing. First, high-dose iron supplements can cause GI discomfort at the best of times, and the nausea that sometimes accompanies semaglutide (particularly around dose increases) can make iron tablets genuinely unpleasant. Smaller, more frequent doses, or switching to a gentler form such as ferrous bisglycinate, often helps; there's more detail on iron and Wegovy if that's your specific question.

Second, fibre supplements (psyllium husk, for example) taken at the same time as other oral medicines can theoretically slow their absorption. This matters less for the weekly semaglutide injection, but if you're also taking oral medicines for other conditions, spacing fibre supplements away from those tablets by an hour or two is a sensible precaution. Your prescriber will flag any specific interactions during your clinical review.

A useful parallel resource is the overview of supplements to approach carefully on semaglutide, which covers this ground in more detail. As for supplements marketed with bold weight-loss claims (fat burners, thermogenics, appetite suppressants) there is no good evidence they add anything meaningful when you're already on a licensed GLP-1 medicine, and some contain stimulants that may increase heart rate or blood pressure. The money is usually better spent on protein-rich food. For context on what treatment itself costs, the Wegovy cost page sets out what's included in a private prescription route.

Making sense of it all: a practical framework

A sensible supplement approach for most people on semaglutide comes down to four things: a daily multivitamin covering the common gaps (vitamin D, B12, folate, iron, magnesium), adequate protein from food or supplement, iron reviewed against your most recent blood tests, and nothing else unless a prescriber or dietitian has a specific reason to recommend it. This is not the same as a personalised plan, blood tests before and during treatment give a much clearer picture than any general list.

The NHS medicines page for semaglutide is a reliable reference for what the treatment itself does and its common side effects. If you have questions about your specific supplement needs, the prescribers at our clinical team can discuss them as part of your ongoing care. And if you're still at the stage of deciding whether semaglutide is right for you, the Wegovy overview is a straightforward place to start.

Check your eligibility for a prescription with us, it takes a few minutes and there's no obligation to proceed.