Cycling on GLP-1s: The complete fueling guide

Semaglutide, tirzepatide, and their siblings slow gastric emptying and blunt the hunger signal. Great for weight loss. Rough for endurance athletes, because cycling — especially at threshold or above — runs on carbohydrate, and carbohydrate has to be eaten. When appetite goes to zero, so does your fueling. Threshold power drops in weeks. Recovery drags. You blame the drug. Often, it's actually underfueling.

The fix isn't heroic willpower. It's a system: small, frequent, planned inputs that work with the suppressed appetite instead of trying to override it.

• Pre-ride (90–30 min out): 30–60g carbs in a form you tolerate. Real food if you can — banana, oat bar, rice cake. Liquid if solids feel heavy. This is where most GLP-1 riders undereat. Set an alarm.
• On-bike: 60–90g carbs per hour for anything above endurance pace. Split across two bottles + a gel every 20–30 min. If you'd normally do 30g/hr, double it. GLP-1s do not reduce your carb oxidation ceiling — they just make you forget to eat.
• Post-ride (0–60 min): 20–30g protein + 40–60g carbs. This is the window that saves you. Skipping it is the #1 cause of stalled recovery on a GLP-1.

The single biggest fueling mistake on GLP-1s is protein collapse. Appetite drops, portions drop, protein drops with them, and lean mass follows. For an active cyclist, target 1.6–2.0 g/kg body weight per day. For a 75kg rider, that's 120–150g. Every day. Non-negotiable.

Practical tactics that work when nothing sounds appetizing:

• Greek yogurt with berries in the morning (25g protein, easy to get down).
• Protein shake at 3pm as a scheduled input, not a "if I'm hungry" thing.
• Chicken/eggs/tofu portion first at dinner. Sides second.
• Cottage cheese before bed. High-protein, low volume, medication-friendly.

Match carbs to work, not to hunger. On a ride day with 90+ minutes at endurance or higher, add 5–8 g/kg total carbs across the day. On rest days, coast at 3–4 g/kg. The appetite signal won't guide you here — you have to plan it.

Expect a 5–10% dip in threshold in the first 2–3 weeks of a new dose. This is fueling, not fitness. If it doesn't recover once your intake stabilizes, that's a signal to check your protein and carb totals — not to blame the medication.

FuelOS is a fueling and training companion. It is not medical advice. If you're losing weight faster than 1% of body weight per week, feeling dizzy on the bike, seeing significant HR drift on easy rides, or getting nauseous with fueling — that's a conversation with the clinician who prescribed the GLP-1, not an app.