His name was William Banting and he is considered to be the father of the Low Carb diet...according to this article. He wrote a Letter on Corpulence about his battle and victory over obesity. In this article/letter he outlines the many "diets" that he went on to lose weight. He visited many doctors and exercised regularly, all to no avail.
Then he went to visit Dr. William Harvey - and ENT doctor and all that changed: