WEIGHT-LOSS surgery is successful because it permanently changes hormone levels, boosting the "I am full" hormone and reducing the "I am hungry" hormone. Now researchers are attempting to mimic this altered hormone balance without having to resort to surgery.
A session at the Festival of Science under way in Liverpool has heard how hormones play a central role in whether we will become overweight or obese and why weight-loss or "bariatric" surgery has proven the only reliable method to ensure long-term weight reduction.
Dr Rachel Batterham of University College London and Dr Carel Le Roux of Imperial College London described studies which explained how the surgery altered levels of three key hormones - the satiety hormone Peptide YY, Ghrelin, the hunger hormone, and CGP-1, which helps to regulate glucose. They also discussed new discoveries about how the satiety hormone affects the "reward/ pleasure" areas of the brain.
"Until last year we believed this hormone only acted on the primitive areas of the brain, but we now know it works on the reward area of the brain," Dr Batterham said.
Two-thirds of the British population were classed as either overweight or obese, something that could be attributed to a conflict between our genes and our environment, she added. "Obesity is actually a normal response to an abnormal environment."
Dr Batterham said our metabolisms evolved when food was scarce and periods of starvation were common. We ate a great deal when food was available and our bodies learned to store the surplus as fat to sustain us during famine. This had represented a "survival advantage" but was a danger to us now that food was always available, making it difficult to diet.
"What you are doing with dieting is fighting the biology we have developed to fight starvation," Dr Batterham said.
Weight-loss surgery alters the hormone mix, allowing the body to reduce excess weight. Dr Batterham is seeking ways to achieve this mix without surgery. It was a challenge given that it involved hormones and these had to be injected, like the hormone insulin.
Dr Le Roux discussed the benefits of bariatric surgery, not just for the patient but for society in general. He argued there should be a tenfold increase in the numbers of people qualifying for weight-loss surgery, which he preferred to call "metabolic surgery".
He said excess weight was a risk factor for type II diabetes and those who received the surgery tended to lose their diabetes. Because of this, these procedures quickly paid for themselves given the reduced burden on the health system, he added.
Metabolic surgery was not about vanity. "It will not make you thin, it is not cosmetic, it is about health." Research was needed to see what types of patients would most benefit from the surgery.
