The US airline industry is facing a new threat to its profits - heavier passengers, a report has found.
The bigger passengers get, the more it costs to get them in the air
According to the US Centers for Disease
Control and Prevention, the average US adult put on ten pounds (4.5 kgs) of weight during the 1990s.
Shifting the extra bulk cost airlines an additional $275m (£149m; 214m euros) in fuel costs in 2000, the report says.
Earnings at airlines have already been under pressure amid waning demand and a record surge in the price of crude oil.
In the US, a number of carriers have gone bust while others are struggling to survive in an ever more competitive market place.
While it is relatively easy to check the weight of a traveller's luggage and charge those that bust limits, it is much harder to regulate a person's waistline.
Hand luggage is one thing; love handles, it seems, are another.
Food firms have come under fire over their menus
Some firms have toyed with the idea of charging obese travellers for two seats, but it is not a practice that has taken off industry-wide.
Last year, the Federal Aviation Administration increased by ten pounds the average passenger weight they use to calculate aircraft loads.
Since then crude oil prices have hit record levels, with many firms responding by raising the fuel surcharge they add to ticket prices.
The rising level of obesity in the US and in Europe has prompted government health campaigns and harsh criticism of a number of food firms.
Restaurant chain McDonald's has taken the brunt of the attack and has in recent months reworked its menu to include healthier options. The move has helped lift profits.
The prediction by experts, however, is that humans are set to become bigger, putting increasing pressure on airline profit.