LUBNA ISLAM, HER dark eyes rimmed with turquoise liner, has always struggled with her weight. Born in the United Arab Emirates, she slimmed down when she was at medical school in Pakistan but quickly regained weight after returning to Abu Dhabi. "Here all the time you're sitting in air conditioning, cars are available," she explains. It's a relaxing lifestyle. With a BMI of 38, and weighing about 109kg, she decided to have gastric surgery. After the operation she suffered from nasty side-effects. After a second procedure she is more comfortable and now weighs 77kg. I recommend it to my own patients. Bariatric surgery is a dramatic intervention in the body's natural machinery, an extreme response to a condition that for most patients is preventable. But Al Noor Hospital, where Dr Islam works, has seen a surge in demand for such operations. The main bariatric surgeon performs an average of seven operations a week. Most patients are below the age of 35. Many hospitals the world over offer similar services. In Belo Horizonte, Brazil's sixth-largest city, nearly 15,000 patients have sought bariatric surgery at Santa Casa hospital since 2008, though fewer than 1,000 got it. Galzuinda Reis, the hospital's main bariatric surgeon, is happy to offer the operation but worries that too many people want it. This demand is driven by two factors. First, and most obvious, people are getting fatter. Second, although pharmaceutical companies excel at treating the diseases that come with obesity, they have been conspicuously unsuccessful at treating the condition itself. This is not for a lack of incentives. The average American would much prefer to be thinner. More than half of America's adults went on a diet in 2010. A good anti-obesity drug would be a blockbuster. But regulators have banned more diet drugs than they have approved. Fen-Phen, made by Wyeth, worked quite well but posed risks to the heart. In 1997 America's Food and Drug Administration (FDA) asked Wyeth to withdraw it voluntarily because of its effect on heart valves. Over the following decade drugs from Sanofi-Aventis and Abbott were dropped for fear of other health risks. Until this year the FDA had not approved a diet drug since orlistat in 1999. That one is still sold, with decidedly unglamorous gastrointestinal effects. Now a new batch of medicines is coming on the market. The three front-runners are from companies in California. In September Vivus launched Qsymia in America. The drug combines phentermine, which suppresses the appetite by boosting leptin, and topiramate, a migraine drug that seems to help patients feel full. Next year Arena will launch its diet drug, Belviq, which acts on serotonin receptors to make patients feel more satisfied. Orexigen, the third company, is testing a drug that combines bupropion, an antidepressant, with naltrexone, which is used in alcoholics to block the brain's opioid receptors. Patients who took high doses of Qsymia for a year, combined with diet and exercise, lost 10.9% of their body weight, whereas a control group taking a placebo lost only 1.6%. Those taking Belviq, combined with diet and exercise, lost an average of 5.8%, compared with 2.5% for the placebo group. But these are not magic pills that will put an end to obesity. First, patients still have to go on a diet-and-exercise regime, and even then the weight loss is fairly modest. Second, there are still some safety concerns. In October European regulators rejected Qsymia over fears of its effect on the heart and central nervous system. Third, the drugs are eye-wateringly expensive, and it is not clear that either insurers or consumers will pay. Qsymia costs $160 a month, or nearly $2,000 a year. Vivus says that just one in five potential patients has insurance coverage for the drug. Cut and thrust Bariatric surgery is a more drastic measure, with more dramatic results. A gastric band is fitted around the top part of the stomach, reducing the amount of food that patients can take in without feeling uncomfortable. In the most common version of gastric bypass surgery, still considered the gold standard, the stomach is divided into a small pouch and a larger one, with the small pouch connected directly to the middle of the small intestine. The small pouch makes a patient feel full more quickly, and the intestinal shortcut stops some of the food from being absorbed. In a newer procedure, sleeve gastrectomy, the surgeon cuts out three-quarters of the stomach and staples the remainder shut. The new, much smaller stomach remains connected to the small intestine. Risks include malnutrition and leakage from the new stomach into the abdominal cavity. Dr Islam first tried a gastric band, but pain and vomiting prompted her to have it removed. In May 2011 she had a sleeve gastrectomy which has left her being able to eat only a quarter of the food she used to. Evidence for the effectiveness of bariatric surgery is growing. In a recent study published in the Journal of the American Medical Association (JAMA), gastric bypass patients six years after surgery had on average lost 28% of their body weight, compared with a 0.2% weight gain in a control group that sought but was not given surgery. The surgery patients were also less likely to suffer from diabetes and high blood pressure. An even longer-term study of Swedish patients showed that those who had had bariatric surgery had lower rates of diabetes, heart conditions and cancer than those getting other forms of treatment. Edward Livingston, a bariatric surgeon and an editor of JAMA, thinks there is still a need for more and bigger studies over longer periods before committing many more people to an operation involving a drastic change in the body's natural structure. But the eligibility criteria for bariatric patients are being relaxed in some countries. Last year American regulators authorised gastric bands for patients who are less than severely obese. Research on other medical methods to fight the flab continues. Philip Smith, co-director of obesity research at America's National Institutes of Health (NIH), points to a new understanding of the relationship between microbacteria and obesity. Some bacteria are correlated with being fat whereas others are benevolent workers that help digest food. Jeffrey Gordon of Washington University has already shown that transferring bacteria from fat to skinny mice makes the lean ones chubby. Now scientists are trying to reverse the trick, transferring stools from skinny to fat subjects. Such "transpoosion" would need to improve its branding, but it might be better than radical surgery. As treatments improve, governments need to decide whether they can afford to pay for them. "If two-thirds of your people have this disorder, you can't possibly pay for treatment for two-thirds of patients," says Dr Livingston. In America the number of bariatric operations has levelled off (see chart 1). Insurance companies are often reluctant to pay. Drugs and surgery will not reverse the obesity epidemic on their own, so it is worth trying other methods. One patient in Belo Horizonte, Glaucienne, has been obese since she was a child. Now 35, she is scared of surgery, so is trying to lose weight at Santa Clara with the help of intensive counselling. Finding time to exercise is hard, says Glaucienne, so she is concentrating on her diet, cutting out salty snacks, chocolates and other treats. The most insidious effect of obesity is the likelihood of contracting chronic diseases. Slimming down even a little can have quite big effects; for example, breast-cancer survivors who dieted and lost an average of 3kg saw a 24% drop in the risk of a recurrence. But while lots of people remain fat, the associated ailments represent big business for the drug companies.