About how many adult Americans have the "weight problem"? ______ percent.

[16]In the U.S.A, 30% of the adult population has a weight problem. To many people, the cause is obvious: [17]they eat too much. But scientific evidence doesn’t support this idea Going back to the America of 1910, we find that people were thinner than today, yet they ate more food. In those days, [18]people worked harder physically, walked more, used machines much less and didn’t watch television. Several modern studies have shown that fatter people don’t eat more than thinner people. In fact some investigations report that fat people eat less than thinner people. Recently a study of a research group found the following interesting fact: [19]thinner people are more active than fatter people. Therefore, [20]those who exercise regularly can eat more and still lose a large amount of body fat.