The Potato Diet: What You Should Know Before You Start

It's misguided that this became known as "the potato diet". If I recall correctly, this became a thing when magician Penn Jillette (from Penn & Teller) lost a significant amount of weight under the guidance of Ray Cronise.

The concept was to choose a single-ingredient, natural, plain and boring food to eat for a few days in order to "reset" your expectations for flavour and to flatten your taste/food reward centers. Penn happened to choose potatoes, but that's not relevant. It could have been any other plain and boring food. In fact, the main goal is the re-leveling effect. Weight loss during the 24 was only a side effect of caloric restriction.