Dr Andrew Jenkinson, a consultant in bariatric surgery at University College London Hospital, argues that the conventional approach to weight loss—counting calories and exercising—is fundamentally flawed. In an interview, he explains that the real culprit behind obesity is hormonal disruption, particularly involving leptin, the hormone responsible for regulating appetite and metabolism.
According to Jenkinson, obesity levels are soaring in the Western world, with a third of Americans and a quarter of Europeans now morbidly obese. This has led to a rise in related health issues such as type 2 diabetes, high blood pressure, and even declining life expectancy. While new medical treatments exist, they are costly and risk creating dependency.
Jenkinson explains that leptin, produced by fat cells, should signal the brain’s hypothalamus to reduce appetite and increase metabolism. However, modern diets high in sugar, refined carbohydrates and processed foods raise insulin levels, which in turn block leptin signals. This hormonal interference tricks the brain into believing the body is underweight, causing it to increase hunger and slow metabolism.
He also challenges the emphasis on calorie counting. While calories are a measure of energy, the body can adjust its basal metabolism—how much energy it burns at rest—by as much as 700 kilocalories a day. This means that the body can compensate for low-calorie diets or intense exercise by slowing down metabolism or increasing hunger, making sustained weight loss difficult.
Jenkinson introduces the concept of a “weight set point”, a genetically influenced level at which the brain tries to maintain body weight. For many, this set point is in the overweight or obese range due to genetic predispositions and exposure to Western diets.
To genuinely lose weight, Jenkinson advises avoiding sugar, refined carbohydrates, and vegetable oils. Instead, he recommends home-cooked meals and whole foods, which help reset the weight set point. Exercise, while beneficial for overall health, has limited impact on weight loss unless combined with significant calorie restriction—an approach that is difficult to maintain.
Ultimately, Jenkinson advocates for a shift in mindset: understanding food as a hormonal influencer rather than just a source of calories. This, he believes, is the key to sustainable weight loss.
