"Wellness" encompasses much more than just gyms and diets — it also includes spas, personalized medicine, tourism and real estate. It's an industry worth $4.2 trillion, according to a 2017 report from the Global Wellness Institute.

To trace the way that wellness trends have evolved over the years, business reviews site Yelp analyzed data from customer reviews dating back to 2004 (when Yelp launched). They noted the treatments that have grown the most since the first time they appeared on the platform, and highlighted some of the trends.