"I Can't Live as This Kind of Father"... Anxiety Strikes, Muscle Loss Appears After One Week [Maunza Report]①

Maunza Experience of a 93kg Reporter (First Dose to Week 1)
A Light Dizziness an Hour After the Injection
Weight Loss Achieved, but
Body Fat Increased and Muscle Loss Occurred in One Week

Editor's NoteThe path to treating obesity, a long-standing challenge in the medical field, is opening up. This is thanks to the emergence of GLP-1 (glucagon-like peptide-1) class medications, which affect satiety and appetite suppression. The recently launched "Maunza" in Korea is a dual-acting agent on both GIP (gastric inhibitory polypeptide) and GLP-1, showing 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, caution is needed against the social trend of misusing these medications for cosmetic purposes or mistaking them for a "miracle diet injection." This series was planned as a total of six installments (over 12 weeks), documenting the process as a reporter diagnosed with severe obesity personally experiences the administration, effects, side effects, and lifestyle changes, with the aim of reflecting on the proper use of obesity medications and a healthy life. Not everyone will experience the same effects from Maunza as the reporter did. Readers considering obesity medications, which may come with side effects, should always consult a doctor.

Photo of the reporter just before medication on September 7.

Body weight: 93.1 kg, height: 172.5 cm, body mass index (BMI): 31.3 kg/m². After starting my professional career, frequent company dinners and lack of exercise quickly led my body into "laziness." Over the past decade since joining the company, I gained more than 20 kg and became severely obese. As I approached my forties, anxiety set in as my weight surpassed a critical threshold. The decisive moment for starting a diet was the birth of my daughter. Determined to "live as a healthy father," I received my first injection of the lowest dose (2.5 mg) of the obesity medication "Maunza" in my abdomen on the afternoon of September 7.

After the launch of the 2.5 mg and 5 mg doses of Maunza in August, a high-dose 7.5 mg product was recently introduced in Korea. Following medical advice that starting with a high dose could cause strong side effects or adverse reactions, I began with the lowest dose. It is important to note that Maunza is an obesity medication that can only be prescribed to patients with a BMI of 30 or higher, or those with a BMI of 27 or higher who also have comorbidities such as hypertension or diabetes.

Maunza is administered by injecting it directly into the abdomen, thigh, or the back of the upper arm using a disposable pen. Place the pen horizontally against the skin, unlock it by turning the ring, and then press the top button. The injection starts automatically with the first "click" sound, and after 3-4 seconds, a second "click" signals the end. The pain is similar to a light pinch. After the injection, do not rub the area; let the medication absorb naturally. Since the drug is absorbed slowly into the subcutaneous layer, rubbing the skin may push the medication toward the surface or cause leakage, resulting in an incomplete dose.

While the product should generally be refrigerated, it can be used for up to 21 days at room temperature. It is best to fix the day and time of administration to maintain a consistent interval. If you miss a scheduled dose, a delay of about a day is acceptable, but further adjustments should be made according to your doctor's instructions. Consuming alcohol or caffeine, or injecting right after binge eating, may interfere with the perceived effectiveness of the medication.

About an hour after the injection, I felt a light dizziness, similar to having had a drink. By evening, I felt queasy and bloated. The next morning, my eating speed noticeably slowed down. My appetite was not completely gone, but the bloating made me think, "Eating will make me feel uncomfortable," so I chewed my food longer. For breakfast, I ate a chickpea salad and rye bread; for a combined lunch and dinner around 5-6 p.m., I had chicken breast and soybean sprout bibimbap. My hunger was less intense, and the feeling of fullness lasted longer. The first week was more about "controlling eating speed" and "reducing meal size" rather than a dramatic change in satiety or appetite.

Since the launch of the lowest dosage product of Maunza, 2.5 mg, in August, it has been difficult to obtain. Some pharmacies required prepayment or assigned waiting numbers. The reporter was able to get it only after a week from the prescription. Even now, the low-dose product is said to be hard to find.

Maunza acts on GLP-1 receptors to promote insulin secretion and suppress glucagon secretion when blood sugar is high, thereby controlling blood glucose, reducing appetite, and delaying gastric emptying to induce early and prolonged satiety. In addition, it acts on GIP (gastric inhibitory polypeptide) receptors to assist insulin secretion and regulate fat metabolism, improving the efficiency of energy use in the body. Thanks to this "dual action mechanism" that stimulates both hormones simultaneously, Maunza demonstrates greater weight loss effects than GLP-1-only medications.

In a head-to-head clinical trial comparing Maunza and Wegovy over 72 weeks (about 18 months), the Maunza group saw an average weight reduction of about -20.2%, while the Wegovy group saw a reduction of -13.7%. The proportion of participants who lost more than 10% or 20% of their body weight was also higher in the Maunza group than in the Wegovy group. However, experts consistently point out that these results do not occur equally for all patients, and there are individual differences in response speed and effectiveness.

Park Kyungmin, Director of Seongsu Melting Clinic (specialist in family medicine), who served as an advisor for this series, said, "Maunza is structured so that GIP and GLP-1 are combined with a single peptide (a short protein fragment), with roughly two-thirds GIP binding and one-third GLP-1 binding. However, stimulating both receptors does not mean it is 'unconditionally better than Wegovy,' as the timing and perception of the response differ from person to person."

Body Composition Change Chart for the First Week of Medication. This series will document and show changes in body composition measured using a home InBody device. The effect cannot be confirmed solely by the changes in the first week. However, while body weight decreased by 1.7 kg, changes were observed such as a decrease in body fat mass and skeletal muscle mass.

Within just one week of medication, my body composition reacted sensitively. As of September 7, my weight was 93.1 kg, skeletal muscle mass was 33.6 kg, and body fat mass was 33.8 kg. After one week, on September 14, these changed to 91.4 kg, 32.4 kg, and 34.0 kg, respectively. While my weight decreased by 1.7 kg, I lost 1.2 kg of muscle, and my body fat actually increased by 0.2 kg. Director Park explained, "GLP-1 medications can cause both fluid and muscle loss in the early stages. If you maintain protein intake and add light strength training, the 'quality of loss' will be different." He added, "Responses vary individually, and on average, it is reasonable to discuss weight loss rates on a monthly basis. In the early stages, it is important to slow down your eating speed and increase daily exercise for weight loss, establishing your own lifestyle rhythm."