Obesity (肥胖) may damage the brain’s ability to recognize the feeling of fullness and be satisfied after eating fats and sugars, a new study found. 

The study was a controlled clinical trial in which 30 people considered to be medically obese and 30 people of normal weight were fed glucose (葡萄糖), fats or water (as a control). Each group of nutrients were fed directly into the stomach via a feeding tube on separate days. Researchers were interested in how fats and glucose would individually make various areas of the brain connected to the rewarding aspects of food work. They wanted to know if that would be different in people with obesity compared to those of normal weight.

In people with normal weight, the study found brain signals slowed when either sugars or fats were put into the digestive system — evidence that the brain recognized the body had been fed. At the same time, levels of dopamine (多巴胺) rose in those at normal weight, signaling that the reward centers of the brain were also activated. However, when the same nutrients were given to people considered medically obese, brain activity did not slow, and dopamine levels did not rise. This was especially true when the food was fats.

“The study is very strict and quite comprehensive,” said Dr. I. Sadaf Farooqi, a professor at the University of Cambridge in the UK, who was not involved in the new research. “The way they’ve designed their study gives more confidence in the findings, adding to prior research that also found obesity causes some changes in the brain,” she said.

Caution is needed in interpreting the findings, lead study author Dr. Mireille Serlie said, as much is unknown: “We don’t know when these changes in the brain happen during the course of weight gain. When does the brain start to slip and lose the sensing capacity?”

1.What can we know about the study?

A 30 people participated in the trial.

B Fats and water were fed on the same day.

C Participants were divided into two groups.

D The aim is to find out how fats make the brain work.

解析：选C。C细节理解题。根据第二段第一句可知，该研究是一项对照临床试验，其中30名肥胖患者和30名体重正常的人分别被喂食葡萄糖、脂肪或水作为对照。由此可知，实验对象被分成了两组。故选C。

2.What does the result of the study show?

A Sugars slow the brain signal in the overweight people.

B Fats decrease the dopamine level in normal people.

C The brain activity of the overweight slows when given fats.

D The dopamine level in overweight people doesn’t rise when given sugars.

解析：选D。D细节理解题。根据第三段的“levels of dopamine (多巴胺) rose in those at normal weight...However...dopamine levels did not rise”可知，在体重正常的人群中，当糖和脂肪被放入消化系统，他们的多巴胺水平上升，但是当肥胖人群被提供同样的营养物时，他们的多巴胺水平却没有上升。故选D。

3.What did Farooqi think of the study?

A It’s rigid.

B It’s absurd.

C It’s beneficial.

D It’s challenging.

解析：选C。C推理判断题。根据倒数第二段中的“comprehensive”“gives more confidence in the findings, adding to prior research”可知，Farooqi认为该项研究很全面，他们设计研究的方式为研究结果提供了更多的信心，并且补充了之前的研究。由此可知，他认为该研究很有用。故选C。

4.What do Serlie’s words mean?

A The brain produces the sensing ability.

B We should be cautious of weight gain.

C There are different findings.

D More research is needed.

解析：选D。D推理判断题。根据最后一段的“Caution is needed in interpreting the findings”“as much is unknown”可知，Serlie认为在解释这些发现时要谨慎，因为其中还有很多未知的事情。由此可推测，她认为此项研究不尽完善，需进一步做更多的研究。故选D。