He developed 10 rules for himself, and other bariatric patients, and the weight began to fall off.

CNN: Learning to eat again: Man drops 130 pounds after surgery

Since 2006 nine non-emergency ambulances have been outfitted to support bariatric patients, patients who weigh about 40kg more than would be recommended for their height.

BBC: Ambulance

The mountains of excess flesh soon slip off, so much so that about half of bariatric patients later undergo surgery to remove surplus skin flapping around their abdomen, upper arms and legs.

ECONOMIST: Obesity: A staple in time... | The

Mathur also knew from her own work analyzing the gas makeup of the breath from bariatric surgery patients that those releasing higher levels of methane in their breath tended to have a body mass index (BMI) nearly seven points higher on average than those with lower levels.

CNN: Can you smell obesity?

While techniques have improved considerably in the past 20 years, the bariatric option is still a major procedure in which as many as two out of every 100 patients die on the operating table or soon after the surgery.

CNN: Gov. Christie, I was you -- listen to the docs

The patients in the new study were treated between 2005 and 2007 at 10 centers with a large volume of bariatric procedures.

CNN: Weight-loss surgery safe, but sleep apnea increases risk