Vitamins for Wegovy: what your body needs when appetite drops

Your appetite has fallen, and your nutrient intake may have followed it

Picture this: three weeks into Wegovy, you finish half a plate and feel full. That's the treatment working. But protein, iron, folate, vitamin B12 and vitamin D don't announce their absence, deficiencies tend to creep in quietly over weeks or months before tiredness, brittle nails or low mood give the game away.

Semaglutide slows gastric emptying and reduces hunger signals from the brain; meals shrink before nutrient density does. The practical risk isn't dramatic malnutrition, it's the kind of low-grade insufficiency that blunts energy and recovery. People who were already borderline deficient (vitamin D in the UK is an obvious example, given our limited sunshine) can tip further when food volume drops.

Protein deserves a particular mention. It isn't a vitamin, but preserving muscle during weight loss depends on eating enough of it relative to total calories. On a sharply reduced appetite, protein is often the first thing squeezed out because carbohydrates and fats tend to be more immediately satisfying in small amounts. The NHS healthy weight guidance recommends prioritising protein and fibre at each meal, advice that applies with extra force when those meals are smaller.

This is why the meal structure that works alongside Wegovy matters from day one, not as an afterthought once deficiency symptoms appear.

The vitamins most commonly flagged on GLP-1 treatment

Four micronutrients come up most frequently in clinical practice for people on weight-loss medicines.

Vitamin D. The UK has a population-wide insufficiency problem regardless of treatment, Public Health England has recommended a 10 mcg daily supplement for everyone through autumn and winter for years. On a calorie-restricted diet, dietary sources (oily fish, eggs, fortified foods) often fall further. A simple blood test at your GP surgery establishes your baseline.

Vitamin B12. Found almost exclusively in animal products. Vegetarians and vegans were already at higher risk; smaller portions of meat, fish or dairy tighten that margin. B12 deficiency develops slowly and the neurological symptoms (tingling, fatigue, memory fog) are easy to attribute to other causes.

Iron. Particularly relevant for premenopausal women. Smaller meals often mean less red meat and fewer fortified cereals, and plant-based iron (non-haem) is absorbed less efficiently than the haem iron in meat. Pairing plant iron sources with vitamin C-rich food helps absorption.

Folate. Essential for cell repair and red blood cell production; found in leafy greens, pulses and fortified foods, foods that sometimes reduce on an appetite-suppressed diet. Anyone considering pregnancy should already be taking 400 mcg folic acid daily; that requirement doesn't change on semaglutide.

Calcium and magnesium are worth a mention for people who cut back significantly on dairy. A prescriber who knows your full diet history can judge which of these, if any, require supplementation for you specifically.

What about a standard daily multivitamin, does that cover it?

A multivitamin won't hurt, but it isn't a substitute for knowing what you actually need. Most over-the-counter products contain modest doses that won't correct an established deficiency, and some formulations include nutrients that are genuinely hard to over-consume alongside others (fat-soluble vitamins A, D, E and K) where long-term excess matters. Taking an iron supplement when your ferritin is fine, for instance, adds no benefit.

The better approach: if you are starting Wegovy or have been on it for a few months, ask your GP or prescriber for a standard blood panel including full blood count, ferritin, vitamin D, B12 and folate. Results give you a precise picture rather than a guess. That conversation also matters for anyone reading up on the practical side of life on Wegovy, where nutrition questions come up repeatedly.

Keep your supplement routine simple enough to actually do. If you take a tablet, mornings are easiest, put it where you'll see it, whether that's next to your coffee mug or tucked in your bag alongside everything else in the morning rush. Consistency matters more than the brand on the bottle.

How nume fits into this conversation

This is where a clinician-led service makes a real difference. At nume, every repeat prescription involves a clinical review by a GPhC-registered prescriber, not an automated approval. That means concerns about fatigue, diet quality or suspected deficiency symptoms have a route into a real clinical conversation rather than a forum thread.

nume doesn't prescribe supplements, that sits with your GP or a registered dietitian. What our prescribers can do is flag concerns, note patterns and encourage you to get the blood tests that answer the question properly. If you're weighing up your options or want to understand what clinical oversight on a Wegovy prescription actually involves, a free consultation is the right starting point. There's no obligation; it's an assessment, not a sign-up.

For context on how Wegovy compares to other treatments and what suits different people, the Wegovy comparison pages are a useful read before your consultation. If you have questions about cost, the Wegovy pricing guide explains what's included in a private prescription. When you're ready, start your free consultation with our prescribers. If you are also unsure whether you meet the criteria to begin treatment, the guidance on who qualifies for Wegovy by age is worth reviewing before you book.