Wii Fit Plus contains the same activities that were present in the original Wii Fit, though also has three new strength training activities and three new yoga activities, as well as fifteen new games. One of the new activities is a platformer.
Due to the success of the original, development of Wii Fit Plus started shortly after that of Wii Fit. Early on in development, Nintendo president Satoru Iwata suggested the team implement multi-leveld exercises. This concept, known as the Stroop Effect, was actually implemented in Brain Age: Train Your Brain in Minutes a Day where players had to say the name of the color of the text instead of the word. When implementing the Stroop Effect in a physical manner, game designer Shigeru Miyamoto mentioned that the first thing that comes to mind is drumming so that your arms and legs move independently, though they had already done this in the Wii Music video game, so they had to go back to the drawing board where they considered various concepts that make use of both the Balance Board and the Wii Remote to come up with several games.
Miyamoto stated that he thought people quit playing the original Wii Fit because it was too inconvenient, which led his team to make the game easier to navigate. With this set in mind, the created My Wii Fit Plus, which was recreated four times during development of the game. The purpose was to quickly get to the exercising programs instead of having the user focus on pressing buttons.
During development of Wii Fit, the team had wanted to add a feature where you could weight your own dog, as Miyamoto said "a pet dog is a member of the family, after all." Unfortunately, this feature never made it out, so it was one of the abandoned elements that they had wished to bring to the enhanced version of the game. According to Miyamoto, he sent a copy of the original Wii Fit to Tsunekazu Ishihara of The Pokémon Company, an owner of two dogs, apologizing for the lack of a dog weighing feature. So, in Wii Fit Plus, it was obviously one of Nintendo's priorities to implement this idea. After the developers created Mii-styled dogs for the game, Miyamoto insisted that they then insert Mii-styled cats (apparently Miyamoto had purchased a cat around this time). They also included a feature where you can weight a baby. In order to notice the differences over a large period of time, they included a feature that saves up to ten years worth of data (opposed to the original's three years).
During development of Wii Fit Plus, Shigeru Miyamoto was also working on Wii Sports Resort and New Super Mario Bros. Wii. Of the three games Miyamoto said that Wii Fit Plus had the smoothest development cycle.
Wii Fit Plus has been well received by critics. 1up rewarded the game with an A-, saying "there still isn't much more focus or guidance in Wii Fit Plus, but the ease of use and greater number of enjoyable, not so "exercisey" games within, make it worth it". Matt Casamassina at IGN also appreciated the game, giving it an 8.2/10. The Official Nintendo Magazine gave it a 91%, praising the new content and the customization options, but thought that gameplay wise it is thin.
In the game's first week on sale in Japan, the game sold an estimated 340,000 units, becoming the top selling game of that week. The game sold more than Japanese gaming publication Famitsu anticipated (319,000 units).
- In the snowball fight, the sounds that are made when a player refills his hearts comes directly from The Legend of Zelda: Twilight Princess on the Wii and GameCube.