If you're losing weight on a GLP-1, there's a question worth asking that the number on the scale can't answer: what are you actually losing? Because not all weight loss is created equal — and on a GLP-1, a meaningful share of what comes off can be muscle rather than fat. The good news is that this is largely preventable, and the two levers that protect your muscle are simple and well-established.
Why muscle is at risk on a GLP-1
Whenever the body loses weight in a calorie deficit, some of that loss comes from lean mass (muscle) alongside fat — this isn't unique to GLP-1 medications, it's how rapid weight loss works. Research on GLP-1 therapies has found that roughly 25–40% of total weight lost can come from lean body mass when no steps are taken to protect it. On a GLP-1 the effect can be pronounced, largely because appetite drops so sharply that protein intake often falls well below what the body needs to hold onto muscle.
Muscle isn't just about strength or aesthetics. It's metabolically active tissue — it helps you maintain the results you're working for, supports everyday energy and function, and is far easier to keep than it is to rebuild later. Protecting it during the loss is much smarter than trying to recover it afterwards.
Lever one: hit your protein target
Protein is the single most important nutrient for maintaining muscle during weight loss. The general evidence-based range for preserving lean mass in a deficit is roughly 1.2–2.0 grams of protein per kilogram of body weight per day, spread across the day rather than crammed into one meal. That's a challenge on a GLP-1, because a smaller appetite means you're eating far less overall — so protein has to become the priority in the food you do eat.
Aiming for something like 25–40g of protein per meal is a practical way to get there. When whole-food protein is hard to stomach — which is common when nausea or early fullness is part of your experience — a clean protein supplement makes the target realistic. Proco's Whey Protein Isolate delivers 23g of complete protein per scoop with no proprietary blends, so a single shake can cover a large chunk of your daily target on the days eating is hard.
Lever two: resistance training
Protein gives your body the raw material; resistance training gives it the reason to keep the muscle. The two together are consistently more effective than either alone. You don't need to become a bodybuilder — the research supports something in the range of 2–4 resistance sessions per week covering the major muscle groups. Bodyweight work, resistance bands, or weights all count.
How much difference does this combination make? One 2025 study of adults combining GLP-1 therapy with resistance training and adequate protein found participants lost about 13% of their body weight while losing only around 3% of their muscle — a dramatically better ratio than weight loss with no muscle-protection strategy. The tools work when you use them.
Where creatine fits
Creatine monohydrate is one of the most studied supplements in sports science, and it's particularly relevant during weight loss: it supports strength and training performance, which helps you get more out of every resistance session. A standard 3–5g daily dose is the well-researched amount. Proco's Creatine Monohydrate is dosed to that range and third-party tested every batch.
Putting it together
Protecting your muscle on a GLP-1 comes down to three things done consistently: eat enough protein, train with resistance a few times a week, and cover the gaps on the days your appetite makes whole food difficult. If you'd rather not assemble the pieces yourself, our Performance Stack brings the protein and creatine together in one place — dosed to the ranges used in research, and tested every batch.
Lose the fat. Keep the muscle. That's the whole point.
This article is for general education and isn't medical advice. Supplements support your nutrition and training — they don't diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider about your individual needs, especially while on a prescription medication.