New light shed on who benefits most from weight-loss jabs

New light shed on who benefits most from weight-loss jabs

A recent study indicates that individuals with specific genetic variations may achieve greater weight loss when using medications like Wegovy and Mounjaro for obesity treatment. Researchers from the University of Copenhagen, publishing in the Nature journal, found that certain gene differences connected to appetite and digestion could influence the effectiveness of these drugs. This discovery might explain why some patients experience significant weight reduction while others see minimal results or face severe side effects such as nausea and vomiting.

Weight-loss drugs work by mimicking natural gut hormones that suppress hunger, making users feel satiated. While genetic factors might contribute to individual responses, experts note that other elements—like sex, age, and ethnicity—also play a role. For instance, the study revealed that people of European descent are more likely to carry a particular variant associated with weight loss, with 64% having one copy and 16% possessing two. In contrast, only 7% of African Americans were found to carry the same gene variation.

“The study found a genetic variant associated with weight loss, which was also linked to nausea. People lose more weight if they have this variant,” said Professor Ruth Loos. She added that individuals with two copies of the genes could double their weight loss, averaging about 0.76kg (1.6 lbs) on top of the general effect. However, the findings require further validation through independent research.

Additionally, the research identified another genetic marker tied to severe side effects, particularly vomiting, when taking tirzepatide (Mounjaro). This could mean up to 1% of users experience vomiting 15 times worse than typical. Despite these insights, Professor Naveed Sattar from the University of Glasgow emphasized that the results are still preliminary. “These findings are scientifically interesting, but they are a long way from changing clinical practice,” he noted.

Dr. Marie Spreckley of the University of Cambridge highlighted that genetics is just one component of a broader equation. She pointed out that lifestyle choices, medical history, and treatment specifics—including dosage and duration—also significantly impact outcomes. For example, women are more than twice as likely to lose 15% of their body weight on Mounjaro compared to men, according to prior research. Younger individuals, those of white or Asian ethnicity, and others with certain characteristics also tend to benefit more, though the exact reasons remain unclear.

The study, based on data from 15,000 participants who used weight-loss medications, showed an average of 11.7% body weight reduction over eight months. Some patients lost up to 30%, while others saw little to no change. This variation was analyzed using genetic information collected by 23andMe, which allowed researchers to connect specific variants with drug efficacy. In the future, combining genetic and clinical data could support personalized treatment decisions, a concept known as precision medicine.

Currently, most weight-loss drugs are purchased privately through online pharmacies, with over 1.6 million people in the UK trying them in the past year. The NHS only provides Wegovy and Mounjaro to a small group with obesity and related health conditions. While the study offers promising insights, more rigorous trials are needed to confirm the balance of benefits and risks, as highlighted by Professor Sattar. “We really need more robust trial data to better define the impact of these and other newer therapies,” he stated.