Thinner isn’t always better. A number of studies have (1)_____ that normal-weight people are in fact at higher risk of some diseases compared to those who are overweight. And there are health conditions for which being overweight is actually (2) _____. For example, heavier women are less likely to develop calcium deficiency than thin women. (3)_____ among the elderly, being somewhat overweight is often an (4)_____ of good health.

    Of even greater (5)_____ is the fact that obesity turns out to be very difficult to define. It is often defined (6)_____ body mass index, or BMI. BMI (7)_____ body mass divided by the square of height. An adult with a BMI of 18 to 25 is often considered to be normal weight. Between 25 and 30 is overweight. And over 30 is considered obese. Obesity, (8)_____, can be divided into moderately obese, severely obese, and very severely obese.

    While such numerical standards seem  (9)_____, they are not. Obesity is probably less a matter of weight than body fat. Some people with a high BMI are in fact extremely fit,  (10)_____ others with a low BMI may be in poor  (11)_____. For example, many collegiate and professional football players  (12)_____ as obese, though their percentage body fat is low. Conversely, someone with a small frame may have high body fat but a  (13)_____ BMI.

    Today we have a(n)  (14)_____ to label obesity as a disgrace. The overweight are sometimes  (15)_____ in the media with their faces covered. Stereotypes  (16)_____ with obesity include laziness, lack of will power, and lower prospects for success. Teachers, employers, and health professionals have been shown to harbor biases against the obese.  (17)_____ very young children tend to look down on the overweight, and teasing about body build has long been a problem in schools.

    Negative attitudes toward obesity,  (18)_____ in health concerns, have stimulated a number of anti-obesity  (19) _____. My own hospital system has banned sugary drinks from its facilities. Many employers have instituted weight loss and fitness initiatives. Michelle Obama has launched a high-visibility campaign  (20)_____ childhood obesity, even claiming that it represents our greatest national security threat.

答案精析：题目所在句由While引导，表达转折关系，大意为：虽然这些数值标准看上去_______，但其实并不是。再结合下文提及的反驳这一判断标准的原因和例子可知，除BMI以外，衡量肥胖与否还有更多的标准，这一数值并不像数字那么简单。所以空格处的形容词应与“简单”意义相近，D选项代入空格表示，BMI看似直观，然而还有更复杂的界定肥胖的方法，因此正确。

错项排除：A选项表示复杂，但BMI确实复杂而非看似复杂，故排除。B项和C项的含义都与语境不相关，也可排除。