Passage One
Questions 46 to 50 are based on the following passage.
The suggestion that people should ai m for dietary diversity by trying to eat a variety of foods has been a basic public health recommendation for decades in the United States and elsewhere. Now, however, experts are warning that aiming for a diverse diet may actually lead to just eating more calories, and, thus, to obesity. One issue is that people may not interpret“variety” the way nutritionists intend. This problem is highlighted by new research conducted by the American Heart Association. Researchers reviewed all the evidence published related to dietary diversity and saw a correlation between dietary diversity and a greater intake of both healthy and unhealthy foods. This had implications for obesity, as researchers found a greater prevalence of obesity amongst people with a greater dietary diversity.
One author of the new study explained that their findings contradict standard dietary advice, as most dietary guidelines around the world include a statement of eating a variety of foods. But this advice does not seem to be supported by science, possibly because there is little agreement about the meaning of“dietary diversity,” which is not clearly and consistently defined. Some experts measure dietary diversity by counting the number of food groups eaten, while others look at the distribution of calories across individual foods, and still others measure how different the foods eaten are from each other.
Although the findings of this new study contradict standard dietary advice, they do not come as a surprise to all of the researchers involved. Dr. Rao, one of the study authors, noted that, after 20 years of experience in the field of obesity, he has observed that people who have a regimented lifestyle and diet tend to be thinner and healthier than people with a wide variety of consumption. This anecdotal evidence matches the conclusions of the study, which found no evidence that dietary diversity promotes healthy body weight or optimal eating patterns, and limited evidence shows that eating a variety of foods is actually associated with consuming more calories, poor eating patterns and weight gain. Further, there is some evidence that a greater variety of food options in a single meal may delay people's feeling of fullness and actually increase how much they eat.
Based on their findings, the researchers endorse a diet consisting of a limited number of healthy foods such as vegetables, fruits, grains, and poultry. They also recommend that people simultaneously endeavor to restrict consumption of sweets, sugar and red meat. The researchers stress, however, that their dietary recommendations do not imply dietary diversity is never positive, and that, in the past, diversity in diets of whole, unprocessed food may have actually been very beneficial.
46. What has been a standard piece of dietary advice for decades?
A) People should diversify what they eat.
B) People should have a well-balanced diet.
C) People should cultivate a healthy eating habit.
D) People should limit calorie intake to avoid obesity.
47. What did the new research by the American Heart association find?
A) Unhealthy food makes people gain weight more easily.
B) Dietary diversity is positively related to good health.
C) People seeking dietary diversity tend to eat more.
D) Big eaters are more likely to become overweight.
48. What could help to explain the contradiction between the new findings and the common public health recommendation?
A) There is little consensus on the definition of dietary diversity.
B) The methods researchers use to measure nutrition vary greatly.
C) Conventional wisdom about diet is seldom supported by science.
D) Most dietary guidelines around the world contradict one another.
49. What did Dr. Rao find after 20 years of research on obesity?
A) There is no clear definition of optimal eating patterns.
B) Diversified food intake may not contribute to health.
C) Eating patterns and weight gain go hand in hand.
D) Dietary diversity promotes healthy body weight.
50. What does the passage say about people who eat a great variety of food?
A) They are more likely to eat foods beneficial to their health.
B) They don't have any problems getting sufficient nutrition.
C) They don't feel they have had enough until they overeat.
D) They tend to consume more sweets, sugar and red meat.
答案解析：
46. 由题干中的关键词 "standard piece of dietary advice" 和 "decades" 定位到第一段。第一段提到 "The suggestion that people should aim for dietary diversity by trying to eat a variety of foods has been a basic public health recommendation for decades..."，说明几十年来标准的饮食建议是人们应该努力使饮食多样化，所以选A。
47. 由题干中的关键词 "new research" 和 "American Heart Association" 定位到第一段。第一段提到 "Researchers reviewed all the evidence... and saw a correlation between dietary diversity and a greater intake of both healthy and unhealthy foods."，表明追求饮食多样性与摄入更多食物相关，所以选C。
48. 由题干中的关键词 "contradiction" 和 "common public health recommendation" 定位到第二段。第二段提到 "But this advice does not seem to be supported by science, possibly because there is little agreement about the meaning of 'dietary diversity,' which is not clearly and consistently defined."，说明对“饮食多样性”缺乏统一清晰的定义是造成矛盾的原因，所以选A。
49. 由题干中的关键词 "Dr. Rao" 和 "20 years of research" 定位到第三段。第三段提到 "...he has observed that people who have a regimented lifestyle and diet tend to be thinner and healthier than people with a wide variety of consumption."，表明他观察到饮食多样化的人反而不如饮食规律的人健康，即多样化的食物摄入可能无益于健康，所以选B。
50. 由题干中的关键词 "eat a great variety of food" 定位到第三段。第三段提到 "...there is some evidence that a greater variety of food options in a single meal may delay people's feeling of fullness and actually increase how much they eat."，说明食物种类繁多可能会延迟饱腹感，导致人们吃得更多，所以选C。
