The irony of Wegovy and Mounjaro: High-risk patients are alienated from weight-loss drugs

“There is no clinical data for people with a body mass index (BMI) below 30 kg/m² who have no underlying medical conditions. We are ‘bravely’ using a new drug with no long-term safety data, in a way that differs from the licensure criteria.”

Wegovy, the drug that sparked the obesity treatment craze, is approved for weight loss and weight management in obese patients with a BMI of 30 kg/m² or higher, or in overweight patients with a BMI between 27 and 30 kg/m² who have weight-related comorbidities such as dysglycemia (pre-diabetes or type 2 diabetes), hypertension, dyslipidemia, obstructive sleep apnea, or cardiovascular disease.

However, despite these regulatory approvals, Wegovy is increasingly being used to fulfill aesthetic desires. In this environment, overweight patients with serious comorbidities—including diabetes and cardiovascular disease—who genuinely need the medication often cannot access it due to its high cost.

Korea Biomedical Review interviewed Professor Kim Sin-gon of the Department of Endocrinology and Metabolism at Korea University Anam Hospital to discuss the ideal prescribing environment for new obesity drugs and the unmet medical needs in obesity treatment.

Question: BMI is widely used as a standard for judging obesity, but it seems there are limitations to measuring obesity using only weight and height. What are some other measures of obesity besides BMI?

Answer: BMI is the most widely used measure of obesity, but since it’s calculated from weight and height alone, it cannot distinguish between body fat and muscle mass. For example, individuals with high muscle mass -- including athletes -- may be classified as obese based on their BMI, even though they are healthy.

To overcome these limitations, our research team developed the Weight-adjusted Waist Index (WWI), which adjusts waist circumference in relation to body weight to provide a more accurate picture of fat-dominant obesity. It is highly predictive of mortality and metabolic disease, especially in older adults and patients with reduced muscle mass.

Q: The GLP-1 class of drugs, such as Wegovy and Mounjaro, has received much attention for obesity treatment. However, Wegovy is often prescribed outside the approved BMI criteria. Do you see misuse in clinical settings?

A: The GLP-1 class is truly revolutionary. But these drugs are often overprescribed to individuals who are not obese, including those seeking to improve their body shape. In fact, they are frequently prescribed to people with a BMI below 25 -- and sometimes even to individuals with a BMI of 21.

The concern is that these drugs are not intended for short-term use. Like diabetes treatments, they need to be continued long-term to maintain their effects. Many patients regain weight within six months of stopping the medication. In addition to the high cost, side effects must also be considered.

Q: Do patients with normal BMIs request Wegovy prescriptions at university hospitals, too?

A: I had a female patient in her early 30s who requested a prescription for Wegovy after gaining three kilograms. Her BMI was 21, and she could afford the expensive treatment. However, clinical trials for this drug were primarily designed for individuals with a BMI of 27 or higher with underlying medical conditions such as diabetes. Its safety and effectiveness have not been demonstrated in patients with lower BMIs. Prescribing without clinical data should be approached with extreme caution.

Q: What are the known side effects or safety concerns with these medications?

A: Gastrointestinal side effects are common with GLP-1 drugs. There have also been discussions about risks such as retinopathy, sarcopenia, and even suicidal ideation. Although these effects were not observed in the randomized clinical trials (RCTs) that supported approval, in real-world practice, some patients have discontinued the drug due to mood swings caused by appetite suppression.

In particular, regularly stopping and restarting the medication may carry risks of central nervous system (CNS) effects. Since long-term safety data is not yet available, close monitoring for adverse events in real-world settings is essential.

Q: Then who are the patients who most need Wegovy and Mounjaro?

A: Severely obese patients with limited financial resources struggle to access these treatments. Wegovy is expensive—costing about 8 million won ($5,773) for a year’s supply. The paradox is that patients with comorbidities such as diabetes and cardiovascular disease—those who most need the medication—have the least access. Meanwhile, those who want to lose a few kilos for aesthetic reasons, and can afford to pay, have easier access.

Q: How do we resolve this ironic situation?

A: We need clearly defined insurance coverage criteria. The patients in greatest need should be prioritized. In Korea, bariatric surgery is covered by health insurance for patients with a BMI of 35 or higher or those with metabolic diseases. Similar criteria could be applied to GLP-1 drugs.

Another option is conditional reimbursement for patients with a BMI of 30 or higher and comorbidities such as diabetes or hypertension. These conditions could include requirements like achieving a certain level of weight loss or HbA1c reduction. A “conditional payment” model—where reimbursement is withdrawn if the patient fails to respond—could improve access while safeguarding the health insurance system's financial sustainability.

We understand that reimbursement is being considered for Mounjaro, which is not yet available in Korea. Lilly Korea should carefully define reimbursement criteria to ensure appropriate use.

At the same time, access should be restricted for those who use the drug without meeting the criteria. Prescription and follow-up should be limited to specialists. Right now, any physician or clinic can prescribe these drugs, which opens the door to misuse.

Q: What do you think is needed to prevent misuse?

A: As with propofol, we need a monitoring system that goes beyond basic guidelines. A voluntary tracking system involving pharmaceutical companies and the Ministry of Food and Drug Safety (MFDS) could be a practical approach.

Q: Korean companies are also developing alternatives to GLP-1 drugs. What strategies could address the unmet medical needs associated with Wegovy and Mounjaro?

A: While current GLP-1 drugs are effective for weight loss, they also cause muscle loss. Future therapies should focus on preserving muscle mass and maintaining quality of life, even if that means slightly less weight reduction. For example, combining GLP-1 and GLP-2 could improve both gut health and muscle maintenance.

Convenience of dosing, long-term safety, and affordability are also key. It may be difficult to exceed the weight-loss efficacy of Wegovy and Mounjaro, so a viable strategy is to match their effectiveness while minimizing side effects and offering a lower price. This is where Korean companies can be competitive—developing safe, cost-effective alternatives that support reimbursement and patient access.

Q: What are some promising targets or mechanisms for obesity drugs beyond GLP-1?

A: In 2006, Sanofi developed Rimonabant, a drug that blocked the cannabinoid receptor-1. It was approved in Europe but later withdrawn due to side effects such as mood disorders and suicidal ideation.

Recently, Novo Nordisk has revisited this pathway with a compound called monlunabant. The goal is to create a drug that does not cross the blood-brain barrier, thereby avoiding central nervous system side effects.