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 suggests that individuals with specific genetic variations related to hunger and digestion may achieve greater weight loss when using drugs like Wegovy and Mounjaro. Published in the Nature journal, the research could clarify why some people experience significant weight reduction while others see minimal results, or why certain side effects, such as nausea and vomiting, are more pronounced in some users.
These medications work by reducing hunger signals, mimicking the action of a natural gut hormone that promotes satiety. Although genetic factors may play a minor role in determining drug efficacy, experts highlight that other elements—like sex, age, and geographic origin—also influence outcomes. The study analyzed data from 15,000 people taking weight-loss drugs, with participants having previously consented to gene testing via 23andMe. This allowed researchers to examine the relationship between genetic markers and treatment responses.
Genetic Insights and Side Effects
By reviewing millions of genetic variations, scientists discovered a pattern linking certain genes to both weight loss and adverse reactions. Professor Ruth Loos, from the University of Copenhagen, noted that “a genetic variant tied to weight loss was also connected to nausea.” Those with this variant lost an average of 0.76kg (1.6 lbs) more than others, and individuals carrying two copies of the gene could see double that benefit.
“The study found a genetic variant associated with weight loss, which was also associated with nausea. People lose more weight if they have this variant,” said Prof Loos. “If you carry the variant, you will lose more weight.”
The variant is more common among people of European descent, with 64% carrying one copy and 16% having two. In contrast, only 7% of African Americans possess a copy. The research also identified another variant that may heighten the risk of severe vomiting when taking tirzepatide (Mounjaro), potentially affecting up to 1% of users with side effects 15 times stronger than usual.
Prof Loos emphasized that while the genetic effect is modest, it “is similar to other factors and not trivial.” However, she acknowledged that further validation through independent studies is still required.
Complex Influences Beyond Genetics
Dr. Marie Spreckley, from the University of Cambridge, stressed that genetics is just one component of a broader picture. She outlined that “behavioural, clinical, and treatment-related factors” are the main determinants of outcomes. These include exercise routines, dietary habits, and the presence of other health conditions. The study also noted that women are more than twice as likely as men to lose 15% of their body weight on Mounjaro, though the reasons remain unclear.
Demographic factors, such as being younger, white, or Asian, are also associated with greater weight loss, although the exact mechanisms are not fully understood. The type of medication, dosage, and duration of treatment further contribute to varying results.
Future of Precision Medicine
Combining genetic and clinical data might one day enable tailored approaches to weight-loss therapies, a concept known as precision medicine. However, Professor Naveed Sattar, a metabolic health expert from the University of Glasgow, cautioned that “these findings are scientifically interesting, but they are a long way from changing clinical practice.” He emphasized the need for more comprehensive trial data to better assess the risks and rewards of these medications.
