They raise resting heart rate Resting heart rate How many times your heart beats per minute while you are fully at rest. For adults it is usually 60 to 100 beats per minute, and lower in well-trained athletes. More about Resting heart rate , and a faster heart tends to go with lower heart rate variability (HRV). A 2026 meta-analysis of 12 randomised trials in people with overweight or obesity and no diabetes found that GLP-1 drugs raised heart rate by 3.5 beats a minute on average against placebo: 3.4 for semaglutide injections (Ozempic, Wegovy), 4.5 for oral semaglutide, 2.1 for tirzepatide (Mounjaro, Zepbound) and 7.3 for orforglipron (Zhang and colleagues, 2026). The meta-analysis did not pool HRV. One small crossover trial of liraglutide in 27 people with type 2 diabetes and coronary disease found that SDNN SDNN The standard deviation of all NN intervals in a recording, in milliseconds. It measures overall variability, and its value depends strongly on how long the recording lasts. More about SDNN fell by 34 ms and RMSSD RMSSD Root mean square of successive differences: an HRV metric built from how much each heartbeat interval differs from the next, in milliseconds. It mainly reflects vagal activity. More about RMSSD fell too, while mean heart rate Mean RR The average time between heartbeats in a recording, in milliseconds. Heart rate is the same number upside down: 60,000 divided by the mean RR. More about Mean RR rose by 8 beats a minute (Kumarathurai and colleagues, 2017). The pooled trials of semaglutide and tirzepatide did not report HRV, so the size of any change in your number is unknown. This page is not medical advice, and no wearable reading is a reason to change a dose.
What the trials show
The meta-analysis pooled trials of liraglutide, semaglutide, tirzepatide, orforglipron and retatrutide. Every drug raised heart rate compared with placebo. In the network analysis that ranks doses against each other, orforglipron 36 mg had the largest rise (about 9 beats a minute) and tirzepatide 5 mg the smallest (about half a beat, not clearly different from placebo). The rise is modest on average, but an average hides a spread, and prescribing information asks doctors to watch resting heart rate.
The mechanism is not fully settled. GLP-1 receptors sit in the heart’s sinus node Sinus node The heart's natural pacemaker, a small patch of cells that starts every normal heartbeat. Left alone it fires about 100 times a minute; the vagus nerve holds it lower at rest. More about Sinus node and in the brainstem, but isolated heart tissue does not speed up when exposed to the drugs, so the review puts the rise down at least partly to more sympathetic Sympathetic nervous system The "fight or flight" branch of the autonomic nervous system. It speeds up the heart and makes it pump harder, but it acts too slowly to drive beat-to-beat HRV. More about Sympathetic nervous system drive or less vagal input.
What that means for HRV
Heart rate and HRV are tied together in two ways, as a 2014 review by Jerzy Sacha explains (Sacha, 2014). The same nervous system steers both, and there is simple arithmetic: the gap between beats is 60,000 ms divided by heart rate, so the same small wobble in rate makes a smaller gap in milliseconds when the heart is faster. A few extra beats a minute at rest will tend to shave a little off RMSSD even if the nervous system has not changed much. In the liraglutide trial, the fall in SDNN stayed significant after adjusting for the change in heart rate, which points to a nervous system effect on top of the arithmetic. How much the newer drugs move HRV is unknown without trials that measure it.
Two things pull the other way. Weight loss raised vagal HRV in most of the 12 studies gathered by a 2022 review (Mattos and colleagues, 2022), and these drugs produce large weight loss over months. Blood sugar, blood pressure and sleep apnoea often improve as well. So the first weeks and the first year may look different: a quick heart rate effect, then a slow gain from the weight that comes off. The liraglutide trial is a caution: HRV fell over 12 weeks despite significant weight loss, and whether the larger weight loss on the newer drugs tips the balance has not been tested. See does losing weight raise HRV?
The first weeks also bring nausea, smaller meals, sometimes dehydration and broken sleep, each of which moves the number on its own.
How to read your own data
- Tag the start and every dose step. Doses usually rise every four weeks. Compare each step with the weeks before it rather than with the months before the drug.
- Read heart rate and HRV together. A resting heart rate a few beats higher with a slightly lower HRV fits the trials. See HRV vs resting heart rate.
- Judge the weight effect over months. A slow rise in the monthly average as weight falls is the pattern to look for.
- Keep the reading routine fixed. Nausea and smaller meals may change when you eat and sleep; keep the measurement at the same point of your day.
For other medicines, read do medications affect HRV? If you have diabetes, see does diabetes affect HRV?
When to talk to a doctor
Never stop, skip or change a GLP-1 dose because of your HRV or heart rate reading. Tell your prescriber if your resting heart rate stays well above its usual level, or if you have palpitations, chest pain, fainting, severe stomach pain or vomiting that does not settle. HRV cannot diagnose anything.