As reports pile up of weight rebounding after injections of the obesity drugs Mounjaro and Wegovy, climbing mountains instead of taking shots is emerging as an alternative — a play on words Koreans call "Mountain-jaro."
Mounjaro topped 1.5 million cumulative prescriptions in the 10 months after its domestic launch in August 2025, according to the Health Insurance Review and Assessment Service on the 13th. Adding Wegovy's 1.04 million cumulative prescriptions, the two drugs have already surpassed 2.5 million.
In clinical trials, Mounjaro produced weight loss of up to 22.5%, while Wegovy showed reductions of around 15% at most, earning the drugs the nickname "miracle shots."
The problem is that stopping treatment brings the weight back. Patients who halted injections at week 36 regained weight, and side effects including pancreatitis, gallstones and cholecystitis have been reported. Monthly costs run from 290,000 won to 600,000 won depending on the dose, a considerable financial burden.
That backdrop is not unrelated to the growing number of people choosing mountains over injections. Hiking, once considered the preserve of people in their 40s and 50s, is drawing attention as a diet workout among those in their 20s and 30s. Celebrities have publicly cited hiking as their weight-loss secret, further stoking interest among younger people.
The core reasons hiking is gaining attention are effectiveness and sustainability. Walking a moderately steep trail burns roughly 430 to 550 kilocalories an hour, comparable to what a 70-kilogram adult burns in an hour of swimming.
Hiking burns twice the calories of ordinary walking and works the whole body, combining aerobic and anaerobic exercise. It also improves insulin sensitivity, making blood sugar easier to control, and as muscle mass grows, glucose uptake and consumption improve, helping prevent diabetes.
When Mounjaro stops, the weight comes back; when hiking stops, the muscle remains. Running has the edge for short-term weight loss and rapid calorie burn, but for sustained effort that builds lower-body muscle while also managing stamina and mental health, hiking is the better option, experts say.
Weight lost through medication returns once the medication stops, but the muscle and stamina built climbing mountains do not disappear easily. This autumn, that is reason enough to reach for hiking boots instead of a prescription.
