Kangaroos have muscular bodies for a variety of reasons. Male muscular kangaroos are more appealing to females than those with fewer muscles. Kangaroos have the strongest and most muscular legs of any hopping animal. Above all, kangaroos are genetically predisposed to be muscular. Pure muscle accounts for 50% of their total weight. As a result, they are naturally buff animals. There are many reason as to why male kangaroo so buff and strong.