EXERCISE and diet programs are all but useless in helping obese people shed weight permanently, prompting calls from an Australian expert for more public hospitals to offer gastric surgery.
University of Melbourne professor of medicine Joseph Proietto said recent research showed that while obese people who made the effort could shed weight in the short term, after four to five years the lost weight was almost completely regained.
Far from being due to laziness, this appeared to be caused by hormonal changes as the body sought to return to what it considered its benchmark weight.
In today’s Medical Journal of Australia, Professor Proietto said doctors "must no longer ignore the scientific evidence . . . that once someone becomes overweight, that state is physiologically defended" by the body. "This newly discovered biology explains the high failure rate of obesity management," Professor Proietto wrote. "We must focus our attention on primary prevention and stop children from becoming obese.
"Finally, we must help the long-suffering obese in their struggle to maintain a reduced weight. In the absence of safe and effective pharmacological agents that can be used long-term, bariatric surgery is the most successful intervention for sustained weight loss."
Professor Proietto wrote that while genetic factors were known to cause a predisposition to obesity, genetic mutations could not have happened fast enough to explain the surge in obesity rates in recent decades.
Instead, he said epigenetic changes — in which genes are switched on or off in response to environmental exposures in the womb or early infancy — were now thought to be responsible.
Efforts by obese people to shed weight ran into trouble because their bodies threw hormonal switches designed to undermine their efforts.
Three studies of overweight patients treated with a very low energy diet or a structured weight loss program for at least three years found that while participants lost an average of up to 22 per cent of their weight within the first two years, by five years the loss had been pegged back to as little as 5.5 per cent, or had even disappeared completely.
In contrast, trials of bariatric surgery — which can involve either a plastic band being placed around the upper stomach to suppress appetite — found weight reductions of between 21 per cent and 38 per cent up to 10 years after the procedures.