GLP-1 Weight Loss Medications: What to Eat, How to Protect Muscle and What to Know Before You Start

If it feels like everyone you know is either on a GLP-1 medication, thinking about one or arguing about them at dinner, you're not imagining it. Experts surveyed by U.S. News named GLP-1 drugs the most impactful health trend of 2026, and market researchers call weight loss and GLP-1s the most talked-about corner of wellness right now.

This guide won't tell you whether you should take one. That's a decision for you and your doctor. What it will do is explain how these medicines work, what the common side effects are, and the everyday habits that make a huge difference to how you feel on them: eating enough protein, lifting something heavy and planning for the long run.

What are GLP-1 medications?

GLP-1 stands for glucagon-like peptide-1, a hormone your gut releases after you eat. It tells your pancreas to release insulin, slows down how fast your stomach empties and sends "I'm full" signals to your brain.

GLP-1 medications copy that hormone and make it last much longer. The best-known ones are:

• Semaglutide: sold as Ozempic (approved for type 2 diabetes) and Wegovy (approved for weight management)
• Tirzepatide: sold as Mounjaro (type 2 diabetes) and Zepbound (weight management). It acts on GLP-1 and a second hormone, GIP.
• Liraglutide: an older daily injection sold as Victoza and Saxenda

Most are weekly injections. All of them need a prescription.

Who can take GLP-1 medications for weight loss?

In the US, GLP-1 medications approved for weight management are generally prescribed to adults with:

• A body mass index (BMI) of 30 or higher, or
• A BMI of 27 or higher plus at least one weight-related health condition, such as high blood pressure, type 2 diabetes or high cholesterol

Some are also approved for teenagers aged 12 and over with obesity. Your doctor will look at your full medical history, current medicines and personal goals, not just a number on a chart. Insurance coverage varies a lot, so it's worth asking about cost early on.

They're not a good fit for everyone. People who are pregnant or trying to become pregnant, people with certain thyroid cancers in their family, and people with a history of pancreatitis usually need a different approach.

How much weight do people lose on GLP-1s?

In the large clinical trials, people taking semaglutide for weight management lost around 15% of their body weight on average over about 68 weeks, and people on the highest dose of tirzepatide lost around 20%. Those are averages from trials that also included diet and activity advice. Some people lose much more, some much less.

These medicines can also bring benefits beyond the scale. Semaglutide is approved to lower the risk of heart attack and stroke in adults with heart disease and overweight or obesity, based on a large trial called SELECT. Research is ongoing in areas like kidney disease, sleep apnea and liver disease.

Common side effects of GLP-1 medications

Most side effects involve the digestive system, and they're usually worst when you start or move up a dose:

• Nausea
• Vomiting
• Diarrhea or constipation
• Bloating, burping and heartburn
• Feeling full very quickly
• Tiredness

Less common but more serious risks include pancreatitis, gallbladder problems, low blood sugar (mainly with other diabetes medicines) and dehydration that can affect the kidneys. The medicines carry a warning about a type of thyroid tumor seen in rodents, so they aren't prescribed to people with a personal or family history of medullary thyroid cancer or a condition called MEN2.

Call your doctor straight away for severe stomach pain that won't go away, persistent vomiting, signs of dehydration or a lump in your neck.

What to eat on GLP-1 medications

When your appetite drops, it's easy to eat too little of the stuff your body needs most. The goal shifts from eating less to eating well in smaller amounts.

Put protein first

Aim to eat the protein on your plate before anything else. Many dietitians suggest people losing weight on GLP-1s aim for roughly 1.2 to 1.6 grams of protein per kilogram of body weight a day, but your needs depend on your size, kidney health and goals, so ask your care team for your number.

Easy protein sources when you're not very hungry:

• Greek yogurt or skyr
• Eggs
• Cottage cheese
• Fish, chicken or tofu
• Lentils and beans (also great for fiber)
• Milk or a protein shake when solid food feels like too much

Eat smaller meals, more slowly

Your stomach empties more slowly on these medicines. Big plates are a recipe for nausea. Try smaller portions, eat slowly and stop as soon as you feel satisfied rather than full.

Go easy on greasy, fried and very sweet foods

Rich, fatty meals tend to make nausea and reflux worse. Many people find plainer, lighter meals easier.

Get enough fiber and fluids

Constipation is common. Fiber from vegetables, fruit, whole grains and beans helps, as long as you drink enough with it. Dehydration is a real risk if you're eating and drinking less, especially if you're also dealing with vomiting or diarrhea. Our guide to how much water you need is a good starting point.

Watch alcohol

Alcohol can worsen stomach side effects and low blood sugar, and many people say their desire to drink drops anyway. If you drink, keep it light.

Muscle loss on GLP-1s: why strength training matters

Here's the part that doesn't get talked about enough. When you lose weight fast, not all of it is fat. In some GLP-1 trials that measured body composition, lean mass made up roughly a quarter to more than a third of the weight lost. Lean mass includes muscle, and muscle is what keeps you strong, steady on your feet and able to do everyday things as you age.

You can't completely prevent some lean mass loss during weight loss, but two habits help a lot:

1. Strength training at least twice a week. Squats, push-ups, rows, lifting weights or resistance bands. Our strength training for beginners plan works at home.
2. Eating enough protein, spread across the day.

Think of it like this: the medication helps with the "less" side of the equation, and strength training plus protein protect the "keep what matters" side.

What happens when you stop taking a GLP-1?

This is the big question, and the honest answer is that for many people, weight comes back. In an extension of one major semaglutide trial, people who stopped the medication regained about two-thirds of the weight they'd lost within a year, and improvements in blood pressure and blood sugar faded too.

That's not a moral failing. Obesity is a chronic condition, and these medicines treat it while you take them, a bit like blood pressure medicine works while you take it. If you're considering stopping, plan it with your doctor. The habits you build while on the medication (strength training, protein, fiber, sleep, regular activity) are your best protection.

Compounded and online GLP-1s: be careful

When brand-name GLP-1s were in short supply, many compounding pharmacies and online clinics sold their own versions. The FDA has since declared those shortages over and has warned about dosing errors and unapproved products, including some sold online that weren't what they claimed to be.

If you're getting a GLP-1, make sure it's prescribed by a licensed clinician who has seen your medical history, and that it comes from a licensed pharmacy. Never buy "research peptides" or products from social media sellers.

Questions to ask your doctor before starting a GLP-1

• Am I a good candidate, and which medicine fits my health history?
• How will we handle side effects as the dose goes up?
• How much protein should I aim for?
• Should I see a dietitian or a physical therapist?
• Will it interact with my other medicines?
• What's the plan if I want to stop, or if I'm planning a pregnancy? (Wegovy's label, for example, advises stopping at least two months before a planned pregnancy.)
• How will we know it's working beyond the scale?

Frequently asked questions about GLP-1 medications

Is Ozempic the same as Wegovy?

They contain the same active ingredient, semaglutide, but they're approved for different uses and come in different doses. Ozempic is approved for type 2 diabetes. Wegovy is approved for weight management and for reducing heart risk in certain adults.

Can you build muscle on a GLP-1?

Many people can maintain or even build some muscle with regular strength training and enough protein, especially if they're new to lifting. It takes deliberate effort because you're eating less.

Why do I feel tired on a GLP-1?

Eating much less, dehydration and low protein can all leave you drained. Check that you're drinking enough and getting protein at every meal, and tell your doctor if it doesn't improve.

Do I still need to exercise on a GLP-1?

Yes. Exercise protects muscle and bone, supports your heart and mood, and is one of the strongest predictors of keeping weight off if you stop the medicine later.

Weight is only one part of your health. Find out how all 8 dimensions of your wellness are doing with our free wellness wheel quiz.