For an endurance athlete, losing muscle directly threatens your watts, your recovery, and your overall stamina. If you want to drop weight without sacrificing your pedal power, you need to make sure your muscles are protected.
What the latest research shows
Research shows that the weight people lose on GLP-1 drugs comes from 60%–75% fat and 25%–40% muscle. This is concerning if you want to maintain your power on the bike while losing weight. One of the effects at play here is less activity overall.
A large study analysing Fitbit activity data from adults taking GLP-1 medications revealed that participants moved less as they started losing weight. On average, their daily step counts dropped from 5,047 to 4,487, and their time spent doing moderate-to-vigorous exercise decreased by about 6 minutes daily.
“While many assume that weight loss leads naturally to increased physical activity, our study suggests otherwise. The findings in our study reinforce that exercise cannot be optional for people taking these medications,” explained lead researcher Dr Sajana Maharjan.
When you eat fewer calories due to appetite suppression, your body naturally tries to conserve energy, leading to subtle drops in daily movement. That can accelerate muscle loss. But losing muscle on a GLP-1 isn’t inevitable. By pairing your medication with a targeted approach to training and nutrition, you can reduce the muscle lost to almost zero.
Treat resistance training as non-negotiable
You cannot rely on cycling alone to save your muscle. While pedalling builds heart health and endurance, it doesn’t provide the heavy resistance needed to tell your body to hold onto upper-body, core, and leg strength. Aim for two 30-minute strength sessions per week. Focus on foundational compound movements like squats, lunges, deadlifts, and planks.
Prioritise protein at every meal
When your appetite is low, it’s easy to pick at small meals that lack substance. To preserve muscle tissue, protein must take centre stage. Aim for a consistent intake of protein spread evenly throughout the day, targeting at least 1,6 g (ideally up to 2 g) of protein per kg of body weight. Lean meats, eggs, yoghurt, tofu, and high-quality whey or plant protein powders are your best friends here.
Monitor your power
Track your performance on familiar segments when taking a GLP-1. Pay especially close attention to your watts per kilogram. A slight dip in overall power is normal when eating at a calorie deficit and losing weight. But when your power-to-weight ratio starts going down, you need to make a change.
The big picture
Dropping weight shouldn’t mean dropping power. GLP-1 medications can be a double-edged sword, helping you lose weight while robbing you of muscle. You need to make a deliberate effort to keep your leg strength intact. By lifting weights and keeping your protein intake high, you can protect your hard-earned muscle, maintain or even improve your watts per kilo, and enjoy flying up the hills.