Wearable data on a GLP-1: why your resting heart rate goes up and your scores dip

People who wear a ring or watch often notice something within weeks of starting a GLP-1 receptor agonist: resting heart rate creeps up, HRV drifts down, and readiness or recovery scores look worse even though they feel fine or better. This is expected, it is in the prescribing information, and it is worth understanding before it causes worry.

What the labels say about heart rate

The Wegovy and Saxenda labels tell prescribers to monitor heart rate at regular intervals, tell patients to report palpitations or a racing heartbeat at rest, and say to stop the drug if a sustained increase in resting heart rate occurs. That instruction is a good reason to keep a resting heart rate trend: a wearable makes "sustained increase" something you can show, not just describe.

What happens to HRV

The most detailed trial on this used 24-hour Holter ECG monitoring.

Put together: weight loss itself tends to move HRV up, while the GLP-1 receptor agonist itself appears to push heart rate up and HRV down, at least for liraglutide in that trial. The authors suggested the drug may affect sympathovagal balance. On a wearable, the drug effect may show first, while weight-related changes build over months. The trial population was small and had heart disease and diabetes, so the size of the effect may differ in other people and with other drugs.

What that does to your scores

• Readiness and Recovery dip. Oura's resting heart rate and HRV balance contributors and WHOOP's Recovery all compare you with your own recent baseline. A drug-related rise in resting heart rate looks like poorer recovery until the baseline window catches up.
• Dose steps can repeat it. Each step up the titration ladder can produce a smaller version of the same shift.
• Sleep can move either way. Nausea or reflux in the days after an injection can disturb sleep. Over months, weight loss improves obstructive sleep apnoea, and in December 2024 the FDA approved tirzepatide (Zepbound) for moderate to severe obstructive sleep apnoea in adults with obesity; see the sleep apnoea trial.
• Calories and activity. Lower food intake can mean less energy for training, which shows up in Strain and activity balance. Muscle loss is a risk without resistance training; see GLP-1 and muscle loss.
• VO2 max may rise. It is expressed per kilogram, so losing weight lifts the number even if absolute fitness is unchanged.

When to tell your prescriber

• A resting heart rate that rises well above your pre-treatment baseline and stays there for more than a week or two.
• Palpitations, a racing heart at rest, dizziness or fainting.
• A resting heart rate regularly above 100 bpm. On Saxenda, at least one resting reading above 100 bpm was recorded in 6 percent of patients vs 4 percent on placebo.

Your prescriber sets the dose and decides what to do; the wearable trend is evidence for that conversation.

A practical approach

Record two weeks of baseline data before the first dose if you can. Note each dose change. Expect a step up in resting heart rate in the first weeks and after each dose increase. Read HRV and readiness against the new baseline rather than the old one. Watch the slower trends, weight, waist, lab results, over months. The reading wearable trends page explains baselines, and the side effects page covers the rest of what to expect.

Logging it

Peptide AI puts each injection from the dose log, weight, side effects and lab results on one timeline with resting heart rate, HRV and sleep from wearable integrations. A shift after a dose step is visible at a glance and easy to share with the prescriber.