Why Some Patients See No Weight Loss Despite Spending $700 on Wegovy

"Didn't you start Wegovy?"

A graduate school classmate who had boldly declared at the start of the year that she would lose exactly 5 kilograms showed up still sporting a generous belly, prompting comments from everyone. She said she had been taking Wegovy—the weight-loss secret credited to celebrities like Tesla CEO Elon Musk—for about two months. "I burned through nearly 1 million won on medication, but I haven't lost a single kilogram," she said with a deflated sigh. While others say they feel nauseous just smelling food after the injections, she drew a round of laughter when she revealed that eating pork belly made her mild nausea disappear completely.

Covering the medical field, I hear these bittersweet stories quite often. Shindong, a member of K-pop group Super Junior, also made headlines when he revealed on a variety show that he had "officially been declared to have beaten Wegovy" by his doctor, despite receiving high-dose injections.

GLP-1 receptor agonist obesity treatments such as Novo Nordisk's Wegovy and Eli Lilly's Mounjaro work by reducing obsessive thoughts about food, commonly known as "food noise." Originally developed as diabetes medications that stimulate GLP-1 hormone receptors secreted by the small intestine during eating to promote insulin release, research later revealed their effect on the brain's satiety center, leading to obesity treatment approvals. Surveys of Wegovy users showed many reported reduced food noise—the constant thoughts about food throughout the day.

Mounjaro is a dual agonist that simultaneously stimulates both GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) hormones, reportedly producing greater effects on blood sugar control and weight loss. Acting on GIP receptors enhances metabolic regulation functions including appetite suppression, insulin secretion promotion, and delayed gastric emptying. Clinical trials conducted by Lilly showed Mounjaro achieved approximately 47% greater weight loss on average than Wegovy.

Both medications attract significant consumer interest, and since national health insurance doesn't cover them, prices vary widely among hospitals and pharmacies. Mounjaro is generally slightly more expensive than Wegovy, perhaps because it's known to be more potent. Anecdotally, some people whose appetite was unaffected even by high-dose Wegovy report dramatic appetite reduction after switching to Mounjaro.

According to the STEP 1 study, the landmark clinical trial demonstrating Wegovy's efficacy, approximately 14-15% of patients in the Wegovy group achieved less than 5% weight loss. The medical community classifies patients who fail to achieve at least 5% reduction from initial body weight within 12 weeks of GLP-1 obesity treatment as "non-responders." Some reports indicate the non-responder rate reaches 31% among obese patients with type 2 diabetes.

Reasons cited for non-response to GLP-1 medications include genetic variations, the body's homeostatic resistance, and differences in appetite regulation mechanisms. Mutations in genes determining GLP-1 receptors can reduce drug-receptor binding efficiency, preventing proper signal transmission to the brain. When weight decreases, the body lowers metabolic rate and increases secretion of ghrelin, a hormone that triggers hunger—and some people have particularly strong defensive mechanisms.

As a result of the brain's powerful survival-driven reward mechanisms, food cravings can overwhelm the satiety signals from medication. While GLP-1 receptor agonists can reduce biological hunger, they cannot completely block the brain's dopamine circuits that seek food for pleasure—another factor reducing drug response.

When patients show no response even at higher Wegovy doses, physicians typically attempt switching to Mounjaro. Some reports indicate that certain patients who don't respond to GLP-1 medications show greater weight loss effects with combination psychotropic appetite suppressants like Qsymia.

However, there is no cure-all. No medication—whether Wegovy, Mounjaro, or any other—can solve obesity without improvements in lifestyle habits including diet and exercise.