The supplement nobody mentions at the clinic

When you start a GLP-1, the conversation is almost always about food. Protein targets, nausea, portion sizes, the meals that suddenly feel like too much. That's the right conversation to be having. But there's a quiet, well-studied compound that gets left out of it, mostly because it has nothing to do with appetite and everything to do with what your muscle is made of: creatine.

Creatine has an image problem. It lives in gym bags and pre-workout tubs, associated with people trying to get bigger. On a GLP-1, you are trying to get smaller, so the whole category feels like it belongs to someone else. That instinct is worth questioning. The thing creatine does best — helping muscle do repeated hard work — is exactly the thing that becomes harder to do when you're eating less than your body wants.

What creatine actually is, mechanically

Forget the marketing for a moment. Creatine is a small molecule your body already makes, mostly in the liver, and that you also get from meat and fish. Around 95% of it sits inside your skeletal muscle, where it exists as phosphocreatine — creatine with a phosphate group attached.

That phosphate is the whole point. Your muscles run on a molecule called ATP, which releases energy when it loses a phosphate and becomes ADP. During the first few seconds of any intense effort — a heavy set, a flight of stairs taken fast, standing up from the floor with effort — your muscle burns through its small ATP supply almost immediately. Phosphocreatine is the backup battery. It donates its phosphate to ADP, regenerating ATP on the spot so the effort can continue. More phosphocreatine in the tank means you can sustain hard contractions slightly longer before fatigue forces you to stop.

Supplementing creatine raises the amount your muscles hold in storage, typically by 10 to 40 percent depending on how much your diet already supplied. This is one of the most replicated findings in sports science. It is not a fringe claim or a hopeful extrapolation.

Why this matters more when you're eating less

Here is the connection most people miss. On a GLP-1, your appetite drops, your intake drops, and your body starts looking for energy and amino acids wherever it can find them — including, if you let it, your own muscle. The single most protective thing you can do is keep giving that muscle a reason to stay: regular resistance training that signals "this tissue is still needed."

But training in a calorie deficit is harder. You have less fuel, your recovery is slower, and the quality of each session quietly declines. You manage one fewer rep, then two, then you start skipping the last set because you're tired. Those lost reps are not trivial. The total amount of work your muscles do is one of the strongest signals telling your body to hold onto them.

This is the gap creatine fills. By topping up the phosphocreatine battery, it helps you maintain training quality on days when your fuel is low — squeezing out the reps that would otherwise slip away. It doesn't build muscle out of thin air. It protects your ability to do the work that protects your muscle. On a GLP-1, where preserving the work is the entire challenge, that's a meaningful lever.

There's a second, smaller benefit worth naming honestly. Creatine pulls water into muscle cells, which is part of why it supports performance. This means a few pounds of intracellular water weight, usually one to four, often show up in the first couple of weeks. On a scale-watching journey, that can read as a stall or a regain. It isn't fat. It's water inside the exact tissue you're trying to keep, and it's the reason creatine should be judged by the mirror, the tape measure, and your lifts — not the morning weigh-in.

The form, the dose, and the noise around both

The supplement aisle sells creatine in a dozen "advanced" forms — hydrochloride, buffered, ethyl ester, liquid — usually at a premium and usually with claims of better absorption or no water retention. The evidence does not support paying for any of them. Creatine monohydrate is the form used in the overwhelming majority of studies, it works, and it's cheap. Plain monohydrate powder is the entire recommendation.

Dosing is simpler than the internet makes it. The maintenance dose is about three to five grams a day, taken whenever is convenient. Some people do a "loading phase" — roughly 20 grams a day split into four doses for five to seven days — to saturate their muscles faster. Loading isn't necessary; it just gets you to full stores in a week instead of three to four. If loading upsets your stomach, and on a GLP-1 your stomach may already be sensitive, skip it. Take five grams a day and let saturation build on its own.

Timing barely matters. The old debate about before versus after training is mostly noise; what matters is taking it consistently, because the benefit comes from keeping your muscles saturated over weeks, not from any single dose. Mix it into water, coffee, a protein shake — whatever you'll actually remember.

What it won't do, said plainly

Creatine will not curb your appetite, settle nausea, or accelerate fat loss. It is not a weight-loss aid, and anyone selling it as one is misleading you. It also isn't a substitute for protein — protein supplies the amino acids your muscle is literally built from, and creatine supplies energy for contraction. They solve different problems, and on a GLP-1 you need both solved.

One practical caution worth flagging: creatine works by holding water in muscle, which means staying hydrated matters more, not less, while you take it. GLP-1s already slow digestion and make it easy to under-drink. If you're frequently dehydrated, sort that out first. And if you have kidney disease, clear creatine with your doctor — in healthy kidneys it's been studied extensively and found safe, but pre-existing kidney problems change that calculus.

The honest version of the pitch

Creatine is unglamorous. It's a few grams of white powder that does one narrow thing well: it keeps a backup energy system topped up so your muscles can keep doing hard work when the rest of your body is running lean. On a GLP-1, where the central risk is losing muscle alongside fat and where every training session is fought uphill against a low appetite, that narrow thing turns out to be exactly the right thing.

It is not a shortcut and it won't move the scale in the direction you're hoping. What it does is quieter and more durable: it helps the strength work stick, so that when you reach your goal weight, more of what's left is the muscle you trained to keep.

That's the logic Lean is built around — treating the muscle you keep as the real outcome, not a side effect. It tracks your protein against a target tuned to your weight, logs your lifts so you can see whether you're holding strength or quietly bleeding it, and keeps the small habits like creatine from slipping through the cracks during the months your appetite is working against you. If you want the part of your GLP-1 results that lasts after you stop, Lean is built to protect it: https://lean.lumenlabs.works