In her high school days, chubby Zhu Qianshuang liked the popular male student Qiao Ye but she did not dare to confess to him and could only make up her mind to lose weight. After trying a variety of weight loss methods such as dieting, diet pills, vomiting, electrotherapy, etc., Zhu Qianshuang not only failed to lose weight, she suffered ridicule and was ostracized by her peers. Zhu Qianshuang's long-standing efforts were for nothing, and her crush ended without any outcome. After graduation, the two went their separate ways, as if they had never crossed paths, but what she didn't know was that the joy and sorrow she had experienced had also happened to Qiao Ye, but the two did not express their feelings due to various reasons. The two people who taught each other how to be brave missed each other, disappearing from the other's youth.

祝千双的中学时代，当时还是个胖子的她喜欢上了学校高高在上的男同学乔野却不敢表白，只能痛下决心减肥。在尝试了节食，吃减肥药，催吐，电疗等各种各样的减肥方法后，祝千双不仅没瘦反而遭受到了周围人的排挤和奚落。祝千双坚持了很久的努力被打回了原形，这段暗恋也无疾而终。毕业后的两人各奔东西，仿佛从未备过住何交集，但她不知道的是，她所经历过的欢呼雀跃，低落伤心也同样在乔野的身上发生过，但两人由于种种原因都没有把自己的情感说出口。两个教会彼此勇敢的人就这样遗憾错过，消失在对方的青春里。