The Best Supplements to Take While on Wegovy

Why appetite suppression changes your nutritional picture

The STEP 1 trial, published in the New England Journal of Medicine, showed semaglutide 2.4mg produced around 15% average body-weight reduction over 68 weeks alongside a reduced-calorie diet. That reduction is driven almost entirely by eating less. The problem is that eating less means fewer vitamins and minerals arriving each day, and the deficit is rarely distributed evenly across all nutrients, some fall further than others depending on which foods the nausea pushes you away from first.

Protein is the most clinically important target. During significant weight loss, the body draws on both fat and muscle for energy; adequate protein intake, combined with resistance activity, is the main lever for preserving lean mass. Most dietitians working alongside GLP-1 prescribers suggest aiming for at least 1.2–1.6 g of protein per kilogram of body weight per day, though a personalised target is better set with your clinical team. High-quality sources (eggs, fish, Greek yoghurt, legumes, poultry) should anchor every meal you do manage to eat. A protein supplement (whey, plant-based, or otherwise) can be a practical top-up if eating enough whole food feels hard on a given day.

Understanding what supports your nutrition as a semaglutide user more broadly is worth doing early, before gaps become symptoms.

Vitamin D, B12, and magnesium: the three most frequently flagged micronutrients

Vitamin D deficiency is already widespread in the UK, the NHS semaglutide guidance sits within a broader NHS recommendation that most UK adults consider a daily 10 micrograms (400 IU) supplement through autumn and winter at minimum. On Wegovy, where dairy, oily fish and fortified cereals may be eaten in smaller quantities, a year-round supplement is often sensible. A daily 1,000–2,000 IU D3 tablet costs pennies and takes three seconds. Worth doing.

Vitamin B12 matters because its richest dietary sources are animal products (meat, fish, eggs, dairy) and when portions of these shrink, intake can drop quietly. B12 deficiency takes months to show in blood tests and longer still to produce symptoms, which is why waiting until you feel off is not a good strategy. A daily B-complex or standalone methylcobalamin supplement is low-risk and inexpensive. If you have any reason to suspect absorption issues (previous gastric surgery, for example), ask for a baseline blood test.

Magnesium often goes unnoticed until the GI side effects of Wegovy arrive. Nausea, reduced food variety, and occasional diarrhoea all reduce magnesium intake and absorption simultaneously. Low magnesium shows up as muscle cramps, disrupted sleep, and fatigue, symptoms that can otherwise be misattributed to the medicine itself. Magnesium glycinate or citrate are generally better tolerated than oxide. Take it in the evening, away from other supplements if possible, as high doses can affect absorption of some minerals.

For a closer look at one specific area, the page on Wegovy and iron supplements covers the iron question in detail, particularly relevant if you eat little red meat or have heavy periods.

How gastric slowing affects when and how you take supplements

Semaglutide slows gastric emptying, which is part of how it reduces appetite. The practical consequence for supplements is that anything requiring stomach-acid activation for absorption (iron, certain B vitamins) may behave differently than it did before you started treatment. Timing matters more than it used to.

Iron is the clearest example. Take it on an empty stomach (or as close to one as nausea allows) with a small amount of vitamin C-rich drink, and keep it well away from calcium supplements, antacids, and tea, all of which block absorption. The detail of how semaglutide specifically interacts with iron absorption is covered on the iron and Wegovy page, but the general principle is: space supplements out, check the timing instructions on the packet, and flag any persistent fatigue to your prescriber so they can run bloods rather than guess.

One quick habit worth building: before adding a new supplement, flip the bottle and check the label for calcium content, and if you want a broader guide to what works well alongside the medicine, the page on supplements to take with Wegovy is a good place to start. Many multivitamins and bone-health formulas contain enough calcium to interfere with iron absorption if taken at the same time. That check takes under a minute and has a real effect on whether the iron you take actually reaches your bloodstream.

For a fuller overview of what to avoid alongside semaglutide, the page on supplements not to take with semaglutide covers interactions and red-flag combinations. And if you're weighing up cost and access questions around treatment, the Wegovy cost guide explains what a legitimate private prescription actually includes.

Wegovy is a prescription-only medicine. If you'd like a prescriber to assess your suitability for treatment (and talk through your nutritional baseline as part of that) the team at nume offers a free consultation, reviewed by a GPhC-registered clinician the same day. Speak to our prescribers, and get the supplement conversation right from the start.