Clinical trials have shown that people using weight-loss jabs, such as Wegovy and Mounjaro, lose anywhere between 16% and 21% of their body weight. But the drugs don’t work for everyone.
In those trials, a group of participants lost less than 5% of their body weight (weight loss of 5% or more is considered to be “clinically meaningful”). These so-called non-responders made up 10% to 15% of participants. Anecdotal evidence, provided by obesity experts to Associated Press, suggests that outside the highly controlled confines of clinical trials, as many as 20% of people don’t respond well to the drugs. Why might this be?
First, it’s important to recognise that the causes of obesity are multifaceted. Our understanding of the genetic basis for obesity has grown significantly over the past decade, revealing that for many people, genetic variations have a significant effect on their weight. For example, a 2021 study found that 0.3% of the UK population (equivalent to over 200,000 people) carry a genetic mutation in part of the brain circuitry that regulates appetite, leading to an average 17kg of additional weight by age 18.
