Eating fast until full doubles the risk of obesity

In a linked study, Maruyama and colleagues showed a significant positive association between eating until full and eating quickly in a large sample of overweight Japanese adults.

The study builds on evidence that taking in more energy than we expend is a behavioural factor that leads to obesity. This is thought to result from an evolutionary imperative to take in large amounts of energy when it is available - linked to differences in food availability in our evolutionary past.

At the moment scientists do not know what it is that drives us to eat until full and to eat too quickly, but it may be that these drivers are not changing in parallel with the obesity epidemic. The question is, can they be modified in a situation where food is plentiful.

Other factors examined in the study are the change in social behaviour leading to fewer families eating together, more food being consumed while distracted by, for example watching television and people eating 'fast food' while on the go - promote eating quickly.

Experimental studies show that humans are pretty ineffective at regulating energy intake, relying on visual cues rather than internal feelings of fullness. And there are also studies that show that sedentary people eat more than the very active - prompting research into what exactly it is that promotes satiety. The volume of food consumed is not modified by the energy value of that food and is linked directly to the volume served - seen in larger and larger restaurant food helpings.

More research is needed on what drives eating behaviour and how this contributes to the obesity epidemic.