Suzana Herculano-Houzel

The pitfalls of self-service food


I know a Frenchman who, when he arrived in Brazil a few years ago, turned up his nose at the eating habits of those who frequent self-service restaurants. Mixing rice, potatoes, pasta and farofa on the same plate could only be the work of barbarians with no gastronomic education: in France, after all, the main course usually consists of meat and a single type of carbohydrate – pasta or potatoes or rice, but never all three together.

Self-service restaurants, however, are an invitation to fill your plate with so much variety on offer: you try a little of this, a little of that… and so the Frenchman soon gave in to temptation and learned to pile French fries, pasta, rice and even snacks onto the same plate. The result? He put on more than ten kilos in a year.

Why is it so easy to overeat in fast-food restaurants? The brain has its own mechanisms to encourage us to eat, of obvious importance since this organ alone needs around 500 calories a day to keep functioning. Less appreciated, however, is that it has equally important mechanisms that make us stop eating at every meal.

The orbitofrontal cortex, the part of the cortex between the eyes that appreciates food, has neurons that are sensitive to specific flavors, such as meat, broccoli and lasagna. These neurons have a special feature: the more they are stimulated by the presence of that flavor in the mouth, the less they are able to respond to it during that meal. So the cortex gets tired of that flavor and soon loses the motivation to eat more of it. But other flavors continue to offer pleasure to your specific neurons, which haven’t yet tasted them at that meal – which explains why you can’t stand meat and farofa at the barbecue anymore, but happily accept a mousse for dessert!

A main course consisting of just two or three flavors, therefore, leaves us feeling full much more quickly than the collection of different flavors so easy to assemble in restaurants by the kilo. Protein-rich meals also lead to satiety more quickly than those based on carbohydrates, usually the most abundant offering in restaurants.

The solution for those who frequent a kilo restaurants is to learn to resist the temptation to try a little of everything, select menus rich in protein – and use one last trick to help your neurons feel full: chew, chew, chew.

Originally published in Folha de São Paulo in September 2007.

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