Sentence:  With meat , milk , butter and ice cream , the calorie-heavy U. S. diet <WSD>is</WSD> 40 % fat , and most of that is saturated fat - the insidious kind , says Dr. Keys , that increases blood cholesterol , damages arteries , and leads to coronary disease . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)