SUPERMAN 102 (January 1956)--2nd story, "The Midget Menace" by Edmond Hamilton, Boring and Kaye:
The lilliputian people from the planet Thura come to Earth to study the Metropolis Marvel and learn the source of his super-powers. Like a modern Gulliver, Superman is shackled to the ground with green K. restraints, as the Thurans tell him their plans to conquer the rival planet Varda, once they have made themselves stronger.
Realizing the secret of his powers is in his atomic structure, the Thurans fashion a ray that alters their atomic structure to that of the Man of Steel. Even though the ray works, Superman convinces them it has failed by secretly using the ray on Lois Lane, who gains temporary super-powers.