[Mounjaro Report] ④ Regaining Diet Rhythm Through Exercise

Mounjaro Experience of a 93kg Reporter (Weeks 7-8)
Combining Strength and Cardio: Fat Loss Without Muscle Loss
"Gradually Increase Intensity After Three Months of Low-Intensity Exercise"

Editor's NoteA new path is opening for the treatment of obesity, which has long been a challenging issue in the medical community. This is thanks to the emergence of GLP-1 (glucagon-like peptide-1) class medications, which influence satiety and appetite suppression. The recently launched 'Mounjaro' in Korea is a dual agonist of GIP (glucose-dependent insulinotropic polypeptide) and GLP-1, demonstrating greater weight loss effects than previous treatments and evolving as a therapy for complex metabolic diseases such as diabetes and MASH (metabolic dysfunction-associated steatotic liver disease). However, there is a need to be cautious about the social climate that leads to misuse of these medications for mere cosmetic purposes or misperceptions of them as a 'miracle weight loss injection.' This series was planned as a six-part (over 12 weeks) feature, in which a reporter diagnosed with severe obesity personally experiences the injection process, records its effects, side effects, and lifestyle changes, and explores the proper use of obesity medications and the pursuit of a healthy life. Not everyone will experience the same effects from Mounjaro as the reporter did. Readers considering the use of obesity medications, which can come with side effects, should always consult a physician.

The reason I was able to regain my disrupted diet rhythm during the Chuseok holiday and business trips was thanks to exercise. My baby, who used to wake up several times each night, suddenly started sleeping through the night, giving me some free time in the evenings. Previously, just getting through the day left me exhausted and collapsing into bed, but with uninterrupted sleep, I was able to spend one or two hours at the gym in the evening. If Mounjaro helped lower the volume of my appetite, exercise was the tool that helped put my disrupted daily rhythm back in order.

The first routine I chose was the most basic full-body workout. I worked my lower body with the leg press, pulled my back with the lat pulldown, stimulated the front of my upper body with the chest press, and held my core with planks. After strength training, I added 20 to 30 minutes of cardio on the treadmill or stationary bike. Rather than setting an ambitious goal of 'transforming my body,' my priority was to create a minimum set I could manage even on tired days. What mattered most was not the quality of the workout, but establishing a pattern of consistently moving my body for one to two hours every evening.

Dr. Park Kyungmin, director of Seongsu Melting Clinic and advisor to the 'Mounjaro Report,' explained the exercise principles for patients on obesity medication: "I recommend exercising three to five times a week, for about 30 minutes each session. For the first one to two months, walking and stationary cycling are best to prevent knee injuries." This means that in the initial phase of Mounjaro treatment, the priority should be to consistently accumulate low-intensity cardio that is just enough to get you slightly out of breath, while minimizing joint strain. He added, "From the third month, I recommend focusing on high-intensity exercise, such as stair climbing, brisk walking, and, among strength exercises, lifting dumbbells, gradually increasing the intensity by about 10% each week." In other words, start with walking and cycling to establish a rhythm, and then gradually increase the proportion of high-intensity cardio and strength training, such as stair climbing, brisk walking, and lifting dumbbells.

Changes in body composition during weeks 7 and 8 show the process of regaining a disrupted rhythm through consistent exercise. My weight, which was 93.1 kg in early September, fluctuated between 90 and 91 kg during the Chuseok holiday and business trips, then dropped again to the high 89 kg range and down to 88.5 kg in late October to early November (weeks 7 and 8). Body fat mass also decreased from the low-to-mid 33 kg range to the low 31 kg range. Although there were minor day-to-day fluctuations depending on hydration and fasting status, the trend line clearly shows a 'secondary drop.' In contrast, skeletal muscle mass remained stable, fluctuating between 31 and 33 kg with no significant loss.

Dr. Park stated, "To my knowledge, there are no studies combining Mounjaro with high-intensity exercise. Based on clinical experience, I believe exercise can induce an additional 1-2% weight loss. Mounjaro alone leads to about 15-20% weight loss over a year; with exercise, this increases to about 17-22% per year." While the numbers may not seem dramatically different, in terms of actual body weight, the difference is significant. More importantly, much of this additional weight loss comes from fat, making an even bigger difference in terms of body composition.

Regarding the impact of exercise on weight loss during obesity medication, Dr. Park explained, "GIP (glucose-dependent insulinotropic polypeptide) promotes fat breakdown in adipose tissue while relatively preserving muscle protein synthesis, and selectively improves insulin sensitivity in skeletal muscle. This leads to faster weight loss and better body composition." As for actual clinical data, he noted, "About 60-65% of the weight loss from Mounjaro is from fat mass, while for Wegovy, about 50-60% is from fat mass. Both drugs cause muscle loss, but the relative proportions differ." While the medication itself works to remove more fat, muscle loss is still unavoidable. Dr. Park added, "Since both drugs inevitably cause muscle loss, strength training and sufficient protein intake (1.2-1.5g per kg of body weight) are essential."