Fast way to getting fat

People who gobble down their food and eat until they feel full are three times more likely to get fat compared with people who eat slowly and modestly.

Changing patterns of behavior, driven by the advent of fast food and cheap food, are widely to blame for the obesity pandemic, according to Japanese researchers.

The Osaka University study recruited 1,122 men and 2,165 women aged between 30 and 69 and asked them to closely track their eating habits and body mass index (BMI), a benchmark of obesity.

Around half of each gender said they ate until they were full, while just under half of the men, and just over a third of the women, said they ate quickly.

Those who ate until they were full were twice as likely to be overweight and those who both ate quickly and until they were full were three times likelier to be overweight.

"The combination of the two eating behaviors had a supra-additive effect on being overweight," the study reported in the British Medical Journal (BMJ).

The study distinguished between people who ate until full and those who reported binge eating. Intriguingly, it found those who ate until full had in fact a higher calorie intake than those who gorged.

In a commentary, also carried by the BMJ, Australian nutritionists Elizabeth Denney-Wilson and Karen Campbell suggested that the drive to eat quickly was a genetic survival mechanism - humans are hardwired to over-consume energy when it is available.

This mechanism has run into problems, though, with food that is cheap and instantly available and eaten swiftly, they argued.

"It may be that the changing sociology of food consumption, with fewer families eating together, more people eating while distracted (for example, while watching television), and people eating 'fast food' while on the go all promote eating quickly," said Denney-Wilson and Campbell.

"Furthermore, the increased availability of relatively inexpensive food, which is more energy-dense and served in substantially larger portions, may promote eating beyond satiety."