Every climber dreams about it. Drop the weight, watch your watts per kilo climb, float up the hills.
GLP-1 medications like Ozempic and Wegovy seem to hand you that for free. Lighter body, same engine, better numbers.
Except the engine doesn’t always stay the same. The watts you need might leave with the kilos.
The Watts Per Kilo Math Has a Catch
Power-to-weight is simple arithmetic. It’s watts divided by kilos, which is why riders treat every pound shed as free speed up the climb.
But the equation cuts both ways. If the kilos you lose take watts with them, the number barely moves.
Picture an 80kg recreational rider pushing 240 watts at threshold. That’s 3.0 W/kg. They lose 8kg on a GLP-1 medication and the scale looks glorious.
But the body doesn’t only burn fat when it sheds weight this way. Studies on these drugs keep finding that a quarter to nearly half of the weight lost is muscle, not fat.
So some of that 8kg is the very tissue that turns the pedals. Drop a little power along with it, say from 240 watts to 230, and the sums change. 72kg at 230 watts is about 3.19 W/kg. A real gain, but a small one, and if more muscle goes than that, the gain can vanish completely.
Worth knowing too: nobody has actually tested these drugs on fit, healthy cyclists. Every study so far was run on people losing weight for medical reasons, not athletes chasing watts. And what we do know suggests the drugs make you lighter without making your engine any bigger. Lighter is not the same as fitter.
Why The Muscle Loss Matters More Than You Think
Lean mass isn’t dead weight you’re glad to be rid of. It’s the leg muscle that makes your watts.
Lose a chunk of it and you lose power directly. The weight you drop includes fat-free mass, in other words muscle, and that can account for up to a third of the loss, says Professor David Stensel, exercise physiologist at Loughborough University.
And here’s the bit that should give riders our age pause. In the big weight-loss studies, the muscle people gave up over a year roughly matched twenty years of normal age-related decline.
If you’re in your 50s or 60s, you already feel that slow drip of strength leaving year by year. This can pack twenty years of it into a single season, while the scale cheerfully tells you it’s all going great.
It isn’t inevitable, though. The riders who keep their muscle are the ones lifting weights a couple of times a week and not skimping on protein. That’s what the research keeps landing on. We’re not handing you a training plan, just telling you what it shows.
The Problem Shows Up On Your Long Weekend Ride
Your watts per kilo number is a snapshot, a single hour on a good day. The real test is the back half of a four-hour ride.
GLP-1 medications slow gastric emptying, which is a polite way of saying food sits in your stomach. Getting carbs down mid-ride gets genuinely hard, and your glycogen runs short when you need it most.
The pattern shows up again and again from riders themselves. Fine on the weekday hour. Then a hard, miserable bonk somewhere past the two-hour mark on the weekend club run.
Some report lower heart rate variability and slower recovery between rides too. Think of a fuel tank that empties early, no matter how good the number looked at the trailhead.
The Fair Questions Worth Sitting With
Plenty of riders take these medications for real reasons. Obesity, type 2 diabetes, heart risk. For them this is a different conversation entirely, a legitimate one, and there’s no room here for sneering or talk of cheating.
There’s one point worth raising, though, and it’s a fair one. When people who don’t really need these drugs buy them up, the ones who genuinely do can struggle to get them.
⚠️ None of this is medical advice, and whether a medication fits your life is a conversation for you and your doctor, not a cycling blog. We’re only here for the riding side of it.
And on the riding side, the lesson is simple. The scale is the easiest number to move. The watts are the one that actually drops you on the climb. Chase the wrong one and you can end up lighter, slower, and wondering why.
Frequently Asked Questions
Is Ozempic banned in cycling?
No, not at time of writing. The sport’s anti-doping authorities have not banned these drugs, and riders do not need any special exemption to use them.
For now they sit on a watch list, where officials track their use without penalizing it. That could change.
The head of science at the World Anti-Doping Agency has hinted the rules might be revisited before the 2028 Los Angeles Olympics.
How much muscle do you actually lose on these drugs?
Roughly a quarter to nearly half of the total weight lost is muscle rather than fat. In the largest weight-loss study, people shed about 17kg on average, and close to 7kg of that was lean tissue, much of it the kind of muscle that produces power.
The exact split varies from person to person, and it depends a lot on whether you keep lifting weights.
Can you protect your muscle while losing weight this way?
You can’t switch it off entirely, but you can blunt it. The combination that keeps showing up in the research is strength training two or three times a week plus a solid protein intake.
Some people following that approach have even held onto, or added, muscle while still dropping fat. That’s what the evidence suggests, not a prescription from us.
Would diet and training give better results than the drug?
For most recreational riders without a medical need, the evidence leans yes. Hard, structured training tends to lift your watts per kilo more than weight loss alone does, because it builds power instead of stripping it away.
Do both together, the slow sensible weight loss and the training, and you do better still. The drug is the shortcut that skips the part that actually makes you stronger.
For anyone with a genuine medical reason to be on one, that’s a different conversation entirely.
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