Not too sure how true this but........................
Fat flyers a dragFrom correspondents in AtlantaNovember 6, 2004
US airlines are experiencing a blow-out in fuel costs because so many of their passengers are fat, according to a government report.The average weight of Americans increased by 4.5kg during the 1990s and two-thirds of the population is overweight or obese, the Centres for Disease Control and Prevention said.
As a result, airlines had to spend an extra $US275 million ($364 million) in 2000 alone to burn an additional 1.4 billion litres of fuel to counteract the drag on planes caused by fatter flyers.
"The obesity epidemic has unexpected consequences beyond direct health effects," CDCP spokesman Deron Burton said. "Our goal was to highlight one area that had not been looked at before."
The extra fuel burned also had an environmental affect, as an estimated 3.8 million extra tonnes of carbon dioxide were released into the air, according to the study.

Obesity-related condition killed about 400,000 Americans in 2000, a 33 per cent jump from 1990. On current trends it will become the US's No 1 cause of preventable death.