The first law of home economics states that the amount of food in a supermarket
trolleyrises in direct proportion to the shopper's hunger level.
supermarket trolley 超市购物手推车
be in direct proportion to 与……成正比
But while the danger is well known to shoppers who venture out on an empty
stomach, how the problem arises in the brain has remained a mystery.
venture out 探险；冒险出去
In a new study of hunger's effects on the mind, neuroscientistspieced
together what happens in the brain that makes us buy more food when we are
effect on 对……的作用
piece together 拼凑；七拼八凑
The findings point to ways of overcoming the temptations of the food
aislesand throw fresh light on the rise of obesity over the past 30 years.
throw light on 使……显得清楚；阐明
From a series of brain scans on volunteers, the researchers showed that a
hunger hormonetriggered activity in the brain that made people pay more for junk
food than usual. Equipped with this knowledge, shoppers should be able to
overridethe urge and stick to more healthy shopping, the scientists said.
"You should never make decisions about food when you are starving. When you
go to the supermarket hungry, the food you are drawn to is high-calorie junk
food," said Dr Alain Dagher, a neurologist at the Montreal Neurological
Institute. "You assign way too much value to calories and so way too little to
health and other things."
Dagher and his colleague Deb Tang recruited29 volunteers for the study and,
asked them to rate how much they liked various items of food, from chocolate
cookies and potato crisps to apples and carrots.
recruit v. 招募
The scientists next put the volunteers in a brain scanner and had them
bidup to five dollars a time for food and other objects, such as baseball caps
and T-shirts, that flashed up on a screen.
After each volunteer had bid for 300 items, one bid was taken and compared
with a counterbid generated at random by a computer. If the volunteer bid the
most, they got to eat the food or keep the item at stake.
at random 随机的；任意的
at stake 在紧要关头
Each person took the test twice over two days and beforehand received
either an injection of ghrelin, a hunger hormone that is released by the
stomach, or a shot of salineas a control. The ghrelin jab made volunteers
ravenousfor one to two hours.
Unsurprisingly, the hungry volunteers bid consistently more for food and
less for inedibleitems than the volunteers who had the saline jab. The hungry
people were willing to spend an average of $2.09 for food and $1.32 for other
objects, but on saline bid only $1.82 for food and $1.58 for the inedible
The scientists traced the behaviour to increased activity in a brain region
called the ventromedial prefrontal cortex, which is involved in motivation and
"Ghrelin seems to increase the amount you are willing to pay for food
through this area of the brain. We think this is why you assign greater value to
the food when you are hungry," Dagher said. The research was presented at the
Society for Neuroscience meeting in Washington DC.
But the study found that people did not simply pay more for foods they
liked. Instead, the higher bids were for the high-calorie junk foods.
"When you are hungry you assign way too much value to calories and so way
too little to health and other things," Dagher said.
Dagher believes that simply being aware of the way the brain works could
help people overcome the urge to buy junk food when they are hungry. "We have
this intrinsic value system but we can overrideit with our minds," he said.
The findings support evidence that shows skipping meals to lose weight can
be counterproductive. "If you miss meals, you tend to gain weight because you
get hungrier and eat calorically densefoods," Dagher said.
skip meals 不吃饭
counterproductive adj. 起反作用的；使达不到预期目标的
calorically dense food 高热量食物
"The main reason for the increase in obesity over the past 30 years is the
cost of food. When you look at an item of high-calorie food, its cost is low, so
you're more likely to buy it. And once you have bought it, you are more likely
to consume it.
"The problem is the decision-making before you even sit down to your meal.
That's where you have lost the battle," Dagher said.