B
(2020·江苏卷)
For those who can stomach it， working out before breakfast may be more beneficial for health than eating first, according to a study of meal timing and physical activity.
Athletes and scientists have long known that meal timing affects performance. However, far less has been known about how meal timing and exercise might affect general health.
To find out, British scientists conducted a study. They first found 10 overweight and inactive but otherwise healthy young men, whose lifestyles are, for better and worse, representative of those of most of us. They tested the men's fitness and resting metabolic (新陈代谢的) rates and took samples (样品) of their blood and fat tissue.
Then, on two separate morning visits to the scientists' lab, each man walked for an hour at an average speed that, in theory, should allow his body to rely mainly on fat for fuel. Before one of these workouts, the men skipped breakfast, meaning that they exercised on a completely empty stomach after a long overnight fast (禁食). On the other occasion, they ate a rich morning meal about two hours before they started walking.
Just before and an hour after each workout, the scientists took additional samples of the men's blood and fat tissue.
Then they compared the samples. There were considerable differences. Most obviously, the men displayed lower blood sugar levels at the start of their workouts when they had skipped breakfast than when they had eaten. As a result, they burned more fat during walks on an empty stomach than when they had eaten first. On the other hand, they burned slightly more calories (卡路里), on average, during the workout after breakfast than after fasting.
But it was the effects deep within the fat cells that may have been the most significant, the researchers found. Multiple genes behaved differently, depending on whether someone had eaten or not before walking. Many of these genes produce proteins (蛋白质) that can improve blood sugar regulation and insulin (胰岛素) levels throughout the body and so are associated with improved metabolic health. These genes were much more active when the men had fasted before exercise than when they had breakfasted.
The implication of these results is that to gain the greatest health benefits from exercise, it may be wise to skip eating first.
文章大意：本文是说明文。文章介绍了一项研究，结果表明对于那些能忍受的人来说，不吃早餐锻炼可能对健康更有益。
24．The underlined expression “stomach it” in Paragraph 1 most probably means “__B__”．
A．digest the meal easily
B．manage without breakfast
C．decide wisely what to eat
D．eat whatever is offered
解析：词句猜测题。根据下文working out before breakfast may be more beneficial for health than eating first可知，早餐前锻炼可能比先吃饭再锻炼对健康更有益，因此推断这里说的是那些不吃早饭先锻炼的人，因此推断划线词与B项“不吃早饭能应付”意思相近。故选B。
25．Why were the 10 people chosen for the experiment？__A__
A．Their lifestyles were typical of ordinary people.
B．Their lack of exercise led to overweight.
C．They could walk at an average speed.
D．They had slow metabolic rates.
解析：细节理解题。根据第三段 They first found 10 overweight and inactive but otherwise healthy young men, whose lifestyles are, for better and worse, representative of those of most of us.可知，他们首先找到了10个超重的，不活跃但健康的年轻人，他们的生活方式不论好坏，代表了我们大多数人的生活方式。因此可知，实验时选择的10个人的生活方式代表了普通人的生活方式。故选A。
26．What happened to those who ate breakfast before exercise？__B__
A．They successfully lost weight.
B．They consumed a bit more calories.
C．They burned more fat on average.
D．They displayed higher insulin levels.
解析：细节理解题。根据第六段的As a result, they burned more fat during walks on an empty stomach than when they had eaten first. On the other hand. they burned slightly more calories(卡路里), on average, during the workout after breakfast than after fasting.可知，结果，他们空腹散步时燃烧的脂肪比他们首先吃东西时所燃烧的脂肪要多。 另一方面。平均而言，他们在早餐后锻炼时燃烧的卡路里略多于禁食后。因此可知，锻炼前吃早饭消耗更多一点的热量。故选B。
27．What could be learned from the research？__D__
A．A workout after breakfast improves gene performances.
B．Too much workout often slows metabolic rates.
C．Lifestyle is not as important as morning exercise.
D．Physical exercise before breakfast is better for health.
解析：推理判断题。根据最后一段The implication of these results is that to gain the greatest health benefits from exercise, it may be wise to skip eating first.可知，这些结果的暗示，为了从运动中获得最大的健康益处，先不吃东西可能更明智。因此推断早饭前的体育锻炼对健康更有益。故选D。
