Biohacker Bryan Johnson revealed he was ‘microdosing’ weight-loss drugs but stopped when his sleep ‘degraded’ and he began experiencing heart issues.

The 48-year-old individual, who asserts that his biological age is over ten years younger than his chronological age, shared on X this week that he began administering 0.5 milligrams daily of tirzepatide. This is the active compound found in the weight-loss medications Mounjaro and Zepbound. 

The exact duration for which he was on the medication is uncertain. The typical dosing protocol for the drug generally begins at 2.5mg per week, with gradual increments to a maximum of 15mg per week.

Although he claims to maintain a body fat percentage under 10, Johnson mentioned that he also experimented with liraglutide, marketed as Victoza and Saxenda, as well as semaglutide, more commonly known as Ozempic and Wegovy. 

The drugs are all GLP-1 agonists, meaning they mimic the effects of the hormone glucagon-like peptide-1 (GLP-1) and increase satiety or fullness. 

Johnson did not specify any details regarding weight loss, but he reported that tirzepatide increased his resting heart rate by three beats per minute and reduced his heart rate variability (HRV) by seven. 

HRV refers to the slight fluctuations in the intervals between heartbeats. These fluctuations are typical, and higher HRV is considered by health specialists as an indicator of the body’s improved capacity to handle stress without causing a spike in resting heart rate, thus avoiding undue stress on the heart. 

Conversely, an elevated resting heart rate can make it challenging for the heart to effectively circulate blood throughout the body, raising the likelihood of a heart attack or stroke. 

Biohacker Bryan Johnson, pictured here, revealed he has been ‘microdosing’ GLP-1 medications like tirzapatide

Johnson wrote: ‘GLP-1s raise your resting rate, which can degrade sleep quality and lower HRV.

‘Good to know in case you’re wondering why your heart rate is higher or your sleep a bit worse.’ 

Johnson claimed microdosing liraglutide raised his resting heart rate by six to 10 bpm. Semaglutide increased it by two to four bpm.  

Johnson has previously claimed on his Blueprint blog that his resting heart rate is between 40 and 49 beats per minute (bpm). A resting heart rate below 60 is considered bradycardia, or a low heart rate typically caused by aging, certain medications like beta blockers and intense physical activity.

If the heart beats too slowly, it may not be able to pump enough blood to vital organs and tissues, increasing the risk of heart attack and stroke. 

The biohacker said an increased resting heart rate ‘can degrade sleep quality. 

While a healthy range during the day is 60 to 100 bpm, the average adult’s resting heart rate should be between 40 and 60 bpm while sleeping. 

During sleep, the body’s parasympathetic nervous system signals a need for rest and repair, which lowers heart rate. Palpitations, however, may disrupt sleep, but the increases Johnson noted still put him within a healthy range for sleeping. 

It’s unclear what Johnson’s exact heart rate variability was before or after microdosing GLP-1s, but a healthy range for adults is 20 to 100 milliseconds. 

Resting heart rates change based on what a person is doing. Rest or relaxation generally lowers it, while exercise or stress increases it. HRV measures the amount resting heart rate shifts based on the situation.  

According to the Cleveland Clinic, a higher HRV shows that the nervous system is better able to adapt to stress and new situations than a lower HRV, so a higher HRV is seen as ideal. 

Johnson said microdosing weight-loss drugs increased his resting heart rate and heart rate variability

Though GLP-1 medications are primarily meant to help users lose weight, Wegovy, Victoza and Trulicity (which uses dulaglutide) are all also approved to reduce the risk of cardiovascular risks like heart attacks in people with heart disease. 

The drugs have been shown to lower glucose (blood sugar) and reduce inflammation around the heart, lowering the risk of heart attack and stroke. 

A study presented earlier this year by researchers at Mass General Brigham in Boston found using tirzepatide reduced the risk of people with heart conditions being hospitalized by up to 58 percent. 

And those specifically taking semaglutide, used in Ozempic and Wegovy, were 42 percent less likely to wind up in the hospital compared to patients taking a placebo. 

A 2023 study also found semaglutide was three times more effective than existing heart failure treatments in reversing signs of the disease. 

Johnson claimed he was taking a 0.5-milligram dose of tirzepatide, far less than the initial 2.5 milligram dose once per week that can eventually increase to five, 10 and 15 milligrams weekly. 

However, taking GLP-1 agonists can lead to gastrointestinal symptoms ranging from vomiting and diarrhea to stomach paralysis, as well as low blood sugar, especially in people who do not have diabetes or obesity.