If you've started a GLP-1 or similar weight loss medication, you're far from the only one. More people are using them than ever, and one of the first things you'll probably notice is how much smaller your appetite is.

That's a big part of why they work, but it also means you're getting less protein, fewer vitamins and minerals, less fibre and often less water than you used to. At Nutritional Performance Labs (NPL), we think it's worth focusing on nutrition during this time, even when it feels like the medication is doing all the work.

Below, we go through the supplements worth taking while using GLP-1 medication, why each one matters and which of ours can help.

Why Do You Still Need Supplements on GLP-1 Medication?

Because you’re eating much less, it’s harder to get enough protein, vitamins and minerals from food alone. Supplements help make up the difference, and protein in particular contributes to the maintenance of muscle mass while you lose fat.

This is important because not all the weight you lose on a GLP-1 is fat. In the STEP 1 trial of semaglutide, people lost an average of 13.6 kg, and body scans on a group of participants showed that about 38% of that was lean mass. Muscle makes up roughly half of lean mass, so around a fifth of the weight lost was muscle.

Muscle matters for how you look and how you feel. Holding on to it means you look leaner and fitter as the weight comes off, and it’s what keeps you feeling strong day to day. It also takes a lot longer to build back than it does to lose, so it’s worth protecting from the start.

How Much Protein Do You Need on GLP-1s?

A 2025 joint advisory on nutrition for GLP-1 therapy, put together by four US obesity and nutrition organisations, points to 1.2 to 1.6 g of protein per kilogram of body weight a day while you're actively losing weight. If you'd prefer a simpler number, the same advisory also gives a daily target of 80 to 120 g.

Reaching that target can be difficult when you feel full quickly. Eat the protein on your plate first, before the fats and carbs, and use a protein shake to make up the rest. GLP-1s also slow down how fast your stomach empties, so a lighter, faster-digesting protein is usually more comfortable than a thick, heavy shake.

• Halo Pro blends hydrolysed whey (whey that’s already partly broken down) with whey isolate and DigeZyme® digestive enzymes, for 20 g of protein per serving. It’s a good choice if your stomach feels sensitive. 
• 100% Whey Isolate is made with whey isolate, for 19.9 g of protein per serving with only 0.4 g of fat. It’s a good choice if you want a light, low-fat shake.
• Plant Protein blends pea protein isolate with rice, hemp, chickpea and pumpkin seed protein for 22 g of protein per serving. It’s a good choice if you avoid dairy, since it’s vegan and gluten-free.
• Whey Slim combines whey with collagen and digestive enzymes, for 22.8 g of protein per serving. It’s a good choice if you want a low-carb shake.

We disclose all ingredients and the exact dosage per serving for all our supplements as part of our Full Label Transparency standard, so you know exactly what you’re getting. 

Which Vitamins Should You Take When You’re Eating Less?

The same advisory flags vitamin D, calcium and vitamin B12 as nutrients people on GLP-1s can easily run low on and suggests a multivitamin to make up for what you're not getting from food.

• Vita Pack is a daily pack of seven capsules with the full B-vitamin range, including B12, plus 750 mg of vitamin C, 250 mg of magnesium, 15 mg of zinc and 1,000 mg of fish oil, providing 375 mg of omega-3.
•  Vita Women is an option if you’d prefer a multivitamin made for women. Two capsules a day give you a range of vitamins and minerals, including vitamin D3, iron and folic acid.

How Can You Look After Your Gut Health? 

Because food sits in your stomach for longer, nausea, bloating and constipation are some of the most common GLP-1 side effects. Smaller portions also mean less fibre, which can make constipation worse. Start by eating smaller meals slowly and getting enough fibre and water.

• Digestive Enzymes gives you ten enzymes, including protease for protein, lipase for fat and amylase for carbohydrates, plus 1 billion CFU of probiotics and inulin fibre in two capsules taken with a meal.
•  Zero Bloat pairs a digestive enzyme blend with ginger, peppermint, fennel and slippery elm to support everyday digestion. We recommend taking Zero Bloat two hours before any other medication, so check with your doctor or pharmacist about how to fit it around your GLP-1 dose.

How Can You Stay Hydrated and Keep Your Energy Up?

A lot of your daily water comes from food, so eating less means you take in less fluid without noticing. If you experience nausea or vomiting in the first few weeks of GLP-1 treatment, it’s easy to become dehydrated. Keep a water bottle with you and add an electrolyte sachet to replace the sodium and potassium that plain water doesn’t.

Hydrolytes Sugar Free Electrolytes gives you 500 mg of sodium, 250 mg of potassium and 50 mg of magnesium per sachet, with zero sugar or carbohydrates. 

Can Creatine Help You Keep Your Muscle?

Creatine is one of the most popular supplements for strength and muscle. It increases the energy stores your muscles draw on for short, intense efforts like lifting weights, which can help you maintain your strength in the gym while you’re eating less. It works best when you’re lifting weights regularly.

Creatine Monohydrate gives you 5 g of micronised creatine per scoop with zero kilojoules. We go into more detail on why creatine belongs in your fat loss stack.

The Bottom Line on Supplements While Using GLP-1 

Your GLP-1 medication takes care of your appetite. What you eat and how you train play a role in how much of the weight you lose is fat rather than muscle. Reach your protein target, cover your vitamins, look after your gut, stay hydrated and keep up your strength training, with creatine to support your sessions. Speak to your doctor or a registered dietitian before adding supplements to your treatment plan.

If you're deciding where to begin, start with protein and find the shake that suits you in our full protein range.

Frequently Asked Questions

Can I take supplements while on GLP-1 medication?

Yes, and many people do, since eating less makes it harder to get enough protein, vitamins and fluids from food. Check with your doctor or pharmacist first, especially if you take other medication.

When should I start taking supplements on GLP-1 medication?

Ideally from the week you start treatment. It's much easier to get enough protein and vitamins from day one than to try to make up for months of eating very little.

When is the best time to have a protein shake on GLP-1s?

Whenever it feels easiest to drink. Some people prefer a shake in the morning, while others split one serving into two smaller drinks between meals. Having it every day matters more than the exact time.

Do protein shakes interfere with GLP-1 medication?

No. A protein shake is food in liquid form, so it doesn't change how your GLP-1 medication works. If you have a medical condition or take other medication, check any new supplement with your doctor or pharmacist.

Should I do strength training while on GLP-1 medication?

Yes, if you can. The 2025 GLP-1 nutrition advisory recommends resistance training, such as lifting weights, alongside a good diet to help protect your muscle while you lose weight. Protein and creatine give your muscles what they need, but training is what signals your body to keep them.

Will creatine make me gain weight on GLP-1s?

Creatine draws water into your muscles, so the scale can go up slightly in the first few weeks. That's water stored in the muscle, not fat.

This article is for information only and isn't medical advice.