Supplements alongside GLP-1 medicines: what has evidence

GLP-1 medicines such as semaglutide (Wegovy, Ozempic), tirzepatide (Mounjaro, Zepbound) and liraglutide (Saxenda) work partly by cutting appetite. Eating much less for months raises fair questions: is there enough protein to hold on to muscle, enough fiber and fluid to stay regular, and enough vitamins and minerals? Supplement makers have noticed, and "GLP-1 support" products are now a category of their own.

This guide sets out which supplements have a reasonable case, which do not, and where the research is thinner than the marketing suggests. It does not replace advice from the person prescribing your medicine.

The short answer: food comes first, and the nutrition basics with the best support are enough protein, resistance exercise, fluids and fiber. A protein shake, a fiber supplement or a vitamin D, calcium, B12 or multivitamin tablet can help fill a specific gap. Supplements sold as natural GLP-1 boosters have no good evidence behind them, and one has drawn a US regulator's warning over safety.

What the evidence says

Grades used here: Strong (consistent results from several good-quality human trials), Moderate (good trials, but few or with mixed results), Limited (small or low-quality human studies, or good studies in other groups of people), Insufficient (too little human research to judge) and Evidence of harm. Only one of the supplement questions below has been studied directly in people taking GLP-1 medicines, so most grades rely on research in other groups.

Protein to protect muscle: Limited

Some of the weight lost on any diet or medicine is lean tissue. A 2025 joint Advisory from four US obesity and nutrition organizations notes that higher protein targets of 1.2 to 1.6 g per kilogram of body weight a day have been proposed during active weight loss, against a general adult reference of 0.8 g/kg. Because it is unclear which body weight to use for people with obesity, it also offers a simpler target of 80 to 120 g of protein a day. Protein-rich foods come first; the Advisory says some people meet the target with high-protein shakes, bars and fortified products, and stresses that more protein alone is unlikely to be enough without strength training.

How much protein people on GLP-1 medicines actually need has not been settled by trials. A 2026 systematic review of 16 randomized trials with 7,096 participants found lean mass was generally preserved in proportion to the weight lost, and concluded that evidence on the best nutrition approach remains limited and that protein requirements need further trials.

Creatine with resistance training: Limited

Creatine has not been studied in people taking GLP-1 medicines. In a 2017 meta-analysis of 22 randomized trials in 721 adults with an average age of 57 to 70, creatine taken during resistance training two or three days a week produced 1.37 kg more lean tissue than placebo, with small extra gains in strength. The benefit came alongside training, not instead of it. Whether it changes muscle or function on a GLP-1 medicine is unknown.

Fiber for constipation: Moderate

Constipation is one of the most common side effects. In the trials summarized by the joint Advisory it affected 17% to 24% of people on semaglutide or tirzepatide. A 2022 meta-analysis of 16 randomized trials with 1,251 adults with chronic constipation, not specifically GLP-1 users, found fiber supplements improved symptoms, with psyllium, doses above 10 g a day and courses of at least four weeks working best. Flatulence was more common with fiber. The Advisory adds that fiber from food and adequate fluids should be encouraged, but that fatty or high-fiber foods may be worth limiting in the first few days of treatment while nausea settles. Take fiber supplements with plenty of water, and ask a pharmacist how to space them around other medicines.

Vitamins and minerals: Limited

A 2026 review of six studies with 480,825 adults on GLP-1 medicines found vitamin D deficiency in 7.5% at six months and 13.6% at 12 months, ferritin (an iron store marker) 26% to 30% lower than in people on another type of diabetes medicine, and more than 60% of users eating less calcium and iron than they need. These were mainly observational data, and the authors say they cannot show the medicine caused the shortfalls. The 2026 review of randomized trials found no clinically relevant deficiencies reported, though few trials looked closely.

The joint Advisory's position is practical: supplements can be considered for at-risk nutrients such as vitamin D, calcium and vitamin B12, or a multivitamin and mineral tablet, at appropriate doses and tailored to the person. It lists fatigue beyond what you would expect, heavy hair loss, flaky or itchy skin, muscle weakness, poor wound healing and unusual bruising as signs that may point to a deficiency and are worth raising with a clinician.

"GLP-1 booster" supplements: Insufficient, and one with safety concerns

Products named after GLP-1 imply they copy the medicine. None has trial evidence of that. A 2026 review of supplements for people stopping GLP-1 medicines listed ingredients such as fiber, protein, berberine, chromium and cinnamon, but its author notes the data were extrapolated from people who were not taking GLP-1 medicines.

In August 2026 the US Food and Drug Administration warned one company that its "Evolv GLP-1 Biomimetic" supplement was adulterated. The product contained a yeast-derived peptide that FDA classed as a new dietary ingredient. The company had submitted two safety notifications, FDA concluded both lacked adequate information to show the product would reasonably be expected to be safe, citing potential toxicity, and the company marketed it anyway.

Who wrote the reviews matters

The most detailed review recommending a broad supplement plan during GLP-1 treatment, published in Obesity Pillars in 2025, was written by authors who are all employed by GNC, a supplement retailer. Its suggestions, including multivitamins, protein, creatine, HMB, fiber and probiotics, draw largely on studies outside GLP-1 users. That does not make it wrong, but it is a reason to give more weight to the joint Advisory and the systematic reviews.

A practical checklist

• Aim for protein at every meal, and use a shake or fortified food if appetite makes that hard.
• Do some resistance exercise most weeks; creatine is an optional extra alongside it, not a substitute.
• Drink enough fluid, especially if you have nausea, vomiting or diarrhea, because dehydration can strain the kidneys.
• Add fiber gradually, from food first; psyllium is the best-studied supplement if you need one.
• Ask whether a blood test for vitamin D, iron or B12 makes sense, rather than taking high doses of everything.
• Skip products that claim to boost or replace GLP-1.

US rules and safety

FDA does not approve dietary supplements before they are marketed. A company using a new dietary ingredient must notify FDA at least 75 days before sale with the safety information it relies on, which is the step at issue in the BioDrive letter. A product sold as a supplement but represented as treating or preventing a disease is regulated as a drug. Compounded GLP-1 drugs are a separate issue: in March 2026 FDA sent warning letters to 30 telehealth companies over false or misleading claims about compounded GLP-1 products on their websites, and its advice is to get a prescription from your doctor and fill it at a state-licensed pharmacy.

Tell your prescriber or pharmacist about any supplement you take. Report a suspected side effect from a medicine to FDA MedWatch, and a problem with a supplement through FDA's Safety Reporting Portal. If you have severe stomach pain that does not go away, are vomiting repeatedly or cannot keep fluids down, get medical care promptly, and call 911 in an emergency.

FAQ

Do I need a multivitamin on Zepbound or Wegovy?

Not automatically. A multivitamin and mineral tablet is a reasonable option if your diet has become very limited, and your doctor can check vitamin D, iron or B12 if you have symptoms.

How much protein should I eat on a GLP-1 medicine?

A joint Advisory from four US organizations suggests 80 to 120 g a day as a simple target, or 1.2 to 1.6 g per kilogram during active weight loss. Ask your clinician if you have kidney disease.

Does psyllium help with constipation on GLP-1 medicines?

It has not been studied in GLP-1 users specifically, but it is the best-supported fiber supplement for chronic constipation. Start low and drink plenty of water.

Do "natural GLP-1" supplements work?

There is no good evidence that any supplement copies the effect of a GLP-1 medicine.