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Supplements on GLP-1 Medicines (Wegovy, Ozempic, Zepbound, Mounjaro): What's Studied and What to Skip

On GLP-1 medicines such as semaglutide and tirzepatide, the best-supported add-ons are habits, not pills: in trials, a quarter to a third of the weight lost was lean mass, and exercise alongside the drug kept more fat loss and bone (grade B). Enough protein (grade C), fiber for constipation (grade B) and fluids help. Check B12 only if you are low or take metformin. Skip berberine, which duplicates the drug, and biotin for hair loss.

Published Updated How we grade evidenceEditorial policy

The short version

  • Muscle loss is real: a quarter to a third of the weight lost on these drugs was lean mass, much as with diet alone. Grade A (Eisa 2026; Look 2025).
  • Exercise with the drug: more fat lost and bone kept than with the drug alone, in one 1-year trial. Grade B (Lundgren 2021; Jensen 2024).
  • Protein: experts advise enough of it to protect muscle; no trial has tested a protein target on these drugs. Grade C (Arslan 2026; Mozaffarian 2025).
  • Fiber for constipation: helped adults with chronic constipation, psyllium most. Grade B (van der Schoot 2022).
  • Berberine: BMI about 0.4 lower in placebo-controlled trials, a result that didn't hold without the weakest trials, and never tested with these drugs. Grade C (Liu 2025).
  • Biotin for hair loss: no evidence in people who aren't deficient. Grade D (Patel 2017).

GLP-1 medicines, such as semaglutide (sold as Wegovy and Ozempic) and tirzepatide (Zepbound and Mounjaro), cut appetite and slow the stomach. In trials of adults without diabetes, weight fell by up to 13.9% with semaglutide and 17.8% with tirzepatide against placebo (Moiz 2025). Eating much less brings three problems that supplements are sold for: losing muscle along with fat, gut side effects, and running short of nutrients (Mozaffarian 2025). This guide covers what has been studied for each. It gives no drug doses.

How much muscle do you lose on a GLP-1 drug?

Grade A. In a 2026 meta-analysis of 20 randomized trials (15,782 people), lean mass made up 35.2% of the weight lost on semaglutide, 25.4% on tirzepatide and 26.8% on liraglutide, about the same share as with diet and exercise programs (26.2%). Programs that added resistance (strength) training had the smallest share, 17.5% (Eisa 2026). In a scan substudy of 160 people in a large tirzepatide trial, about 75% of the weight lost was fat and 25% lean mass, on drug and placebo alike (Look 2025). Lean mass includes muscle, water and organs, and no trial has yet measured whether strength or function falls (Batsis 2026).

Does exercise help on a GLP-1 drug?

Grade B. In a 1-year Danish trial, 195 adults who had already lost weight on a low-calorie diet took liraglutide, an exercise program, both, or neither. The combination cut body-fat percentage by 3.9 points, about twice as much as either one alone, and only the combination improved fitness and blood sugar control (Lundgren 2021). In the same trial, bone density at the hip and spine held steady with the combination, compared with placebo (Jensen 2024). Liraglutide is an older, weaker drug, so the result may not carry over exactly to semaglutide or tirzepatide. Expert groups advise resistance training for everyone on these drugs (Mozaffarian 2025).

How much protein do you need?

Grade C. No trial has tested a protein target in people on GLP-1 drugs. A 2026 review proposes a daily protein floor of 1.2 g per kilogram of body weight, rising to 1.6 g for adults with healthy kidneys, spread across meals, plus progressive resistance training (Arslan 2026). Another review suggests protein shakes only to reach that amount when appetite is low (Johnson 2025). Food comes first; a whey protein shake is a convenience, not a requirement. With kidney disease, check with your doctor before eating more protein.

What helps the nausea and constipation?

Grade B for fiber, on indirect evidence. Gut side effects are the main problem with these drugs: in trials, 47% to 84% of people on them had one, most often nausea, vomiting, diarrhea or constipation, against 13% to 63% on placebo (Moiz 2025). No trial has tested fiber supplements in GLP-1 users. Pooling 16 constipation trials in adults (1,251 people), 66% responded to a fiber supplement against 41% on control. Psyllium and pectin stood out, higher doses (over 10 g daily) and courses of 4 weeks or more did better, and gas was more common (van der Schoot 2022). Raise fiber slowly and drink with it. For nausea, expert advice is smaller meals, stopping when full, and less fatty food; there is no supplement trial (Mozaffarian 2025).

Do you need electrolytes or extra fluids?

Fluids matter; electrolyte products are untested. Vomiting and diarrhea can dry you out, and the semaglutide label warns of kidney injury from fluid loss in people with those side effects (DailyMed). We found no trial of electrolyte supplements on these drugs. Drink regularly, and call your prescriber if you can't keep fluids down.

Should you take vitamin B12 or a multivitamin?

Grade B for checking B12 if you also take metformin, a diabetes drug often prescribed alongside: across 4 trials, metformin lowered B12 by 57 pmol/L within 3 months (Chapman 2016). Grade C for the GLP-1 drugs themselves: observational studies of these drugs found vitamin D deficiency in 13.6% of users at a year, iron stores about a quarter lower than on another diabetes drug, and low intake of calcium and iron in most users, but cause and effect weren't shown (Urbina 2026). Take vitamin B12 if a blood test shows you are low, not by default. A basic multivitamin is a reasonable backstop when you eat very little, as reviews suggest, but it hasn't been tested on these drugs (Johnson 2025).

Is berberine "nature's Ozempic"?

Grade C for a small, uncertain weight effect: in 8 placebo-controlled trials of berberine alone, BMI was about 0.4 lower, and not significantly once the 2 weakest trials were left out (Liu 2025), a sliver of what the drugs do. It also lowers blood sugar: in 37 trials in type 2 diabetes, HbA1c (a 3-month blood sugar average) fell by 0.63 points (Xie 2022).

On a GLP-1 drug it duplicates the job and adds risk. No trial has tested the two together. Berberine's own common side effects are constipation and diarrhea (Li 2023), on top of the drug's. It blocks the liver enzymes CYP3A4 and CYP2D6, which clear many common medicines (Bathaei 2025), and adding another glucose-lowering agent matters most if you also take insulin or a sulfonylurea, the drugs the semaglutide label flags for low blood sugar (DailyMed).

Will a supplement stop hair loss?

Grade C that the drugs raise hair loss. A 2026 review of 24 studies found more hair loss with semaglutide and tirzepatide than with older drugs in this class, often telogen effluvium, a temporary shedding that follows rapid weight loss or other shocks to the body, and more often in women (Gupta 2026).

Grade D for biotin. A review found 18 published case reports of biotin improving hair or nails, and every one involved an underlying condition or deficiency; there is no good evidence for healthy people (Patel 2017). High-dose biotin can also throw off blood tests, including thyroid tests and troponin, the test for a heart attack (Moerman 2022). Eating enough protein and having iron and thyroid levels checked if shedding persists is more useful.

What we'd skip

  • Berberine on top of a GLP-1 drug. It adds little or no weight loss (BMI about 0.4 lower in placebo-controlled trials, not robust), stacks gut side effects and blocks drug-clearing liver enzymes (Liu 2025; Bathaei 2025).
  • Biotin for drug-related hair loss. No evidence without a deficiency, and it can skew lab tests (Patel 2017; Moerman 2022).
  • B12 shots or high-dose B12 "for energy" without a blood test. The case for B12 rests on low levels, mainly with metformin (Chapman 2016).
  • "GLP-1 support" blends. We found no trial of any blend in people on these drugs.

Safety and interactions

  • Thiamine (vitamin B1): six case reports describe Wernicke encephalopathy, a brain emergency from thiamine shortage, in people on semaglutide with long-lasting vomiting and fast weight loss; some were left with lasting memory damage or died (Bidesie 2026). Persistent vomiting is a reason to call, not to push through.
  • Oral medicines: the drugs slow the stomach and can change how well pills are absorbed (DailyMed). Tirzepatide lowered blood levels of an oral contraceptive in a trial (Skelley 2024); ask whether you need a backup method.
  • Berberine in pregnancy or breastfeeding: berberine can harm newborns, and NCCIH says not to use goldenseal, a berberine herb, then (NCCIH).
  • Protein: with kidney disease, high protein needs your doctor's OK (Arslan 2026).
  • Fiber: more gas and bloating at first (van der Schoot 2022). Take other medicines a couple of hours apart from a fiber dose, and start low.
  • No interaction studies were found between these drugs and whey protein, psyllium or multivitamins.

When to see a doctor

  • Right away: severe belly pain that won't go away, with or without vomiting (pancreatitis), pain under the right ribs, fever or yellow skin (gallbladder), or signs of dehydration such as dizziness and very little urine (DailyMed).
  • Vomiting for more than a day or two, or new confusion or trouble with eye movements: these can signal dehydration or thiamine deficiency (Bidesie 2026).
  • Shakiness, sweating or confusion if you also take insulin or a sulfonylurea: low blood sugar.
  • Before surgery or sedation: tell the team you take a GLP-1 drug (DailyMed).

What to ask your prescriber

  • Which supplements I take, including berberine or other blood sugar products, and whether any clash.
  • Whether I need B12, vitamin D or iron checked, and when.
  • What protein target and exercise plan suit my health, especially with kidney disease.
  • Whether my birth control pill still works on my drug.
  • What to do if I can't keep food or fluids down.

Don't stop or change a prescribed medicine on your own; ask the prescriber or pharmacist. If you are pregnant, planning a pregnancy or breastfeeding, talk to your doctor or midwife: the semaglutide label says to stop it at least 2 months before a planned pregnancy (DailyMed).

FAQ

What supplements should I take on a GLP-1 medicine? Most people need habits more than pills: strength training (grade B), enough protein (grade C) and fiber if constipated (grade B). Add B12, vitamin D or iron only if a blood test shows you are low.

Can I take berberine with semaglutide or tirzepatide? We'd skip it. It has never been tested with these drugs, adds little or no weight loss, and stacks gut side effects and drug interactions.

Does biotin stop hair loss on a GLP-1 drug? There is no good evidence it helps without a deficiency (grade D), and it can distort blood tests.

How do I keep muscle on a GLP-1 drug? Resistance training plus enough protein. In trials, programs with strength training lost the smallest share of lean mass.

Sources

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