Several years back, the Morning Banana diet became the biggest thing going in Japan. There are multiple variations, including eating only a banana for breakfast, eating one (or two) banana(s) before eating a full breakfast, and eating a banana before every meal. People started to believe that doing this would aid metabolism and help people lose weight faster than normal. The craze went as far as to cause a temporary shortage of the fruit nationwide and stores selling them would typically be sold out before noon when the fad was at full-swing.
“There's no magic ingredient in the [Morning] Banana Diet that results in weight-loss,” EatRight.org says. “The truth is that people can lose weight on a fad diet when calories are limited. However, it's almost always followed by regain of the weight lost.”