A leading scientist from the University of Cambridge has pinpointed a genetic reason why shedding pounds can feel like an impossible battle for many people, linking it to a specific mutation that sabotages feelings of fullness.
The Genetic Hand in Our Hunger
Professor Sadaf Farooqi, a consultant endocrinologist who leads the Genetics of Obesity Study, treats patients with severe obesity. She explains that our body weight is heavily influenced by genes that control the brain pathways regulating hunger. Variants in these genes, commonly found in people with obesity, cause them to feel hungrier and less satisfied after eating.
Professor Farooqi highlighted one gene in particular: the MC4R gene. A mutation in this gene promotes overeating and reduces sensations of fullness. It is estimated that this specific genetic variant is carried by roughly one-fifth of the global population, offering a scientific explanation for the uneven struggle with weight management.
Metabolism and the Modern Environment
The expert further detailed that other genes affect an individual's metabolism—the rate at which they burn energy. This means two people eating the identical meal may store fat and gain weight very differently. While thousands of genes are thought to influence weight, scientists currently understand the detailed role of only about 30 to 40 of them.
This genetic predisposition interacts powerfully with today's environment. With over 60% of UK adults now classified as overweight or obese, according to a 2025 analysis by the Health Foundation, factors like the aggressive marketing of fast food, ubiquitous ultra-processed foods, and limited physical activity opportunities create a perfect storm. Professor Farooqi notes that as a population, "we have become more obese," and those with a higher genetic risk "have done so."
Why New Medications Are a Game-Changer
This complex interplay of genetics and environment is precisely why Professor Farooqi champions the new generation of weight-loss medications. "This is why the weight loss drugs coming on to the market are so effective and so important – they help to combat this," she stated. These drugs work by targeting the very brain pathways that the mutated genes disrupt, helping to regulate appetite and satiety signals.
The revelation underscores that obesity is not simply a matter of willpower but often a chronic biological condition. For the millions carrying genetic variants that amplify hunger, the path to weight loss is fundamentally harder, making medical interventions a crucial tool in addressing the UK's escalating public health crisis.
