[Mounjaro Report] ⑤ The Day I Worried About Hair Loss: A Story of Side Effects

Mounjaro Experience of a 93kg Reporter (Weeks 9-11)
Fear of Potential Hair Loss
Other Side Effects Like Pancreatitis and Depression Also Require Caution

Editor's NoteThe path to treating obesity, once a major challenge in the medical field, is opening up. This is thanks to the emergence of GLP-1 (glucagon-like peptide-1) class treatments, which influence satiety and appetite suppression. The recently launched 'Mounjaro' in Korea is a dual-acting agent targeting both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1, demonstrating greater weight loss effects and evolving as a treatment for complex metabolic diseases such as diabetes and MASH (metabolic dysfunction-associated steatotic liver disease) compared to existing therapies. However, there is a need to be wary of the social climate where such treatments are misused for simple cosmetic purposes or misunderstood as a 'miracle weight loss injection.' This series was planned as a total of six installments (over 12 weeks), with a reporter diagnosed with severe obesity personally experiencing the administration process, recording the effects, side effects, and lifestyle changes, to reflect on the proper use of obesity medications and healthy living. The effects experienced by the reporter may not be the same for everyone. Readers considering the use of obesity medications, which can be accompanied by side effects, should always consult a physician.

At week 9 of Mounjaro administration, for the first time in my life, the word 'hair loss' crossed my mind as I looked at the drain after a shower. As I shook my hair during the process of washing and drying, strands of hair fell out. I had heard countless times that dieting could lead to hair loss, but actually seeing my own hair fall out felt surreal. Common side effects like nausea or constipation seemed manageable if I just endured them, but hair loss was a different story. From the moment I could feel the change in my appearance, not only the drug's effects but also its 'cost' became apparent.

Hair that falls out during the process of drying hair after a shower. When body weight decreases rapidly, the body recalculates where to prioritize the distribution of energy and protein, and in this process, areas that are 'not directly related to survival,' such as hair, may be deprioritized.

When weight drops rapidly over a short period, the body recalculates where to prioritize the distribution of energy and protein. In this process, areas that are not directly related to survival, such as hair, may be deprioritized. It is explained that if stress, lack of sleep, and nutritional imbalance overlap, these signals can become more pronounced. Park Kyungmin, director of Seongsu Melting Clinic and advisor for the Mounjaro report, says, "When weight decreases rapidly and protein intake becomes insufficient, it can result in muscle loss and deterioration in hair condition." This means it is not the drug itself causing hair to fall out, but rather the decrease in nutritional intake and lifestyle changes induced by the medication that can alter the body's metabolic priorities.

The effect of diet medications, which reduce appetite and promote relatively rapid weight loss, comes with side effects. Although there are significant individual differences, being aware of potential side effects is one of the conditions for using weight loss medications in a healthy way. The most frequent side effects that occur as weight drops rapidly are gastrointestinal symptoms. The most common are digestive discomforts such as nausea and diarrhea. However, Director Park explains, "Compared to Wegovy, Mounjaro has a lower frequency and severity of heartburn and nausea," adding, "GIP (glucose-dependent insulinotropic polypeptide) helps reduce nausea somewhat."

From a physician’s perspective, the most concerning side effect is pancreatitis. Director Park notes, "The incidence is extremely low, but it is not easy to detect in advance, so it is difficult to prevent." He adds, "People who lose a lot of weight may develop gallstones, and if those stones block the entrance to the pancreas, pancreatitis can occur." In other words, it is not simply that 'the drug is bad for the pancreas,' but that changes accompanying weight loss (such as gallstones) can become warning signs. In actual diabetes clinical data, acute pancreatitis was very rare but reported several times. In the Mounjaro group, when patients were observed for '100 patient-years,' about 0.23 cases were reported, compared to 0.11 cases in the control group. In simple terms, when hundreds or thousands of people were observed over a long period, pancreatitis was seen as a rare adverse reaction, but if symptoms are suspected, it is necessary to discontinue immediately.

Depression is another concern. Director Park says, "No one dies from dieting, but depression can lead to death," and adds, "Dieting itself can cause depression." He explains that people who once enjoyed life may experience mental instability when suddenly cutting out 'delicious foods,' and those with a history or risk of depression should be especially cautious. Therefore, he recommends, "People who relieve stress only through eating should find another hobby in advance."

As the planned 12 weeks of Mounjaro administration neared its end, clear changes in body composition (weeks 1-11) were observed. From September 7, weight dropped from 93.1 kg to 87.3 kg on November 23, a reduction of 5.8 kg, and body fat mass decreased from 33.8 kg to 30.1 kg, a loss of 3.7 kg. Body fat percentage also fell from 36.3% to 34.0%. Skeletal muscle mass decreased from 33.6 kg to 32.3 kg, a reduction of 1.3 kg.