On a GLP-1 (semaglutide — Ozempic/Wegovy — or tirzepatide — Mounjaro/Zepbound), the nutrition risk comes from eating less, not from the drug stripping out a nutrient. Pick your appetite change and diet to see which nutrients matter most for you — protein, vitamin D, B12, magnesium, electrolytes, fibre — each ranked by cost per dose.
Updated July 2026 · a cost comparison, not medical advice
Medication
Ozempic / Wegovy / Rybelsus
Appetite reduction
Diet
Nutrients that come up most for your profile, roughly in order — each links to the cheapest option by cost per dose. This reflects eating less, not a claim that the medication depletes anything. It is not medical advice.
Rapid weight loss on a GLP-1 comes partly from lean muscle, and reduced appetite makes it hard to hit a protein target. Adequate protein (with resistance training) is the most consistently raised nutrition point for people on these medications.
The deficiency most often reported in GLP-1 users — a 2026 review found roughly 14% were vitamin D deficient at a year. It is also one of the cheapest supplements per dose. Confirm your level with a blood test rather than guessing a dose.
Constipation is one of the most common GLP-1 side effects as gut transit slows. Soluble fibre with plenty of water is the usual first step, and psyllium is the cheapest per dose.
Lower total food intake reduces B12 from meat, dairy and eggs; the risk is higher on a plant-based diet or if you also take metformin. B12 has no upper limit, so it is a low-risk one to keep adequate.
Intake drops with smaller meals, and the early nausea, vomiting or diarrhoea some people get can add losses. Glycinate or citrate are gentler on the stomach than oxide.
GI symptoms plus eating less can lower electrolytes, especially in the first weeks. Supplemental potassium is capped by law (~99 mg/pill), so food (and rehydration) does most of the work — talk to a clinician if you feel weak or lightheaded.
Alongside protein and resistance training, creatine is studied for helping preserve muscle and strength during weight loss. ~5 g/day of plain monohydrate is the well-established dose and the cheapest form.
Some people use them for the nausea and bowel changes that come with slowed digestion. The evidence is modest, so this is an optional, try-and-see one rather than a must.
Eating less lowers iron intake, which matters most if you are plant-based or menstruating. Only supplement iron if a test shows you are low — excess iron is harmful.
Priorities shift with how much your appetite has dropped and whether you eat animal products; the medication choice is for context — the nutrition points are broadly the same across GLP-1s. Always confirm changes with the clinician who prescribed your medication, and never stop or change a medication because of a supplement.
Not in the sense of a drug chemically stripping out a vitamin. GLP-1 medications (semaglutide, tirzepatide) work by reducing appetite, so the real issue is eating less — which can mean less protein and fewer vitamins and minerals overall — plus early GI side effects like nausea or diarrhoea that add losses. The practical response is to prioritise the nutrients hardest to get on a smaller appetite, which the calculator above lists for your profile. Not medical advice — talk to your prescriber.
The ones that come up most are protein (to help preserve muscle during fast weight loss), vitamin D (the deficiency most often reported in GLP-1 users — about 14% within a year in a 2026 review), vitamin B12, magnesium, electrolytes such as potassium, and fibre for constipation. Which matter most depends on how much your appetite has dropped and whether you eat animal products. This tool ranks each by cost per dose; it does not tell you to start anything — confirm with your clinician.
There is no GLP-1-specific number, but preserving muscle during rapid weight loss is the reason protein is raised so often, and appetite loss makes a target hard to hit. General guidance many clinicians use is on the order of 1.2–1.6 g of protein per kg of body weight per day, paired with resistance training. Your prescriber or a dietitian can set the right target for you. Not medical advice.
No — never stop or change a prescribed medication because of a supplement or a website. If you have side effects, that is a conversation with the clinician who prescribed it. This page only compares the cost per dose of nutrients people commonly ask about; it is not a substitute for medical care.