In recent years there has emerged a new trend focused on the body image in the Western countries. Our society is concerned with people's physical appearance and ideal body image. As consequence of this trend, two businesses emerge: fitness centers and plastic surgery clinics. Traditionally the consumers' expenditure in these services and goods has been considered a luxury especially during the economic slowdown. However, in the recent times, (at end of 2000s both service sectors are showing an increasing trend in terms of activity and business size). Thus, customers have seen the practice of fitness and plastic surgery procedures as a necessity rather than a luxury. The two kinds of products considered: fitness practice and plastic surgery procedures are of different nature; however they share several commonalities from the analysis point of view. In particular, referred to the fitness practice business, this involves a parallel increase of related economic sectors such as sports clothing, energy drinks and sports equipment. Related to the Spanish population who exercise regularly, this has evolved from 27% in 2005 to 35% in 2010, which shows a significant increase of the population sportive practices. A significant example of this trend is the fact that in 2009 the 74% of the Spanish public gyms had a fitness room for bodybuilding. On contrast, related to the market of plastic surgery measured by volume of activity, Spain occupies the level 13th position of the international ranking, which is headed by USA. The plastic surgery market embraces low invasive (non surgical) and high invasive (surgical) plastic surgery procedures; between both types, more than 300,000 thousands procedures are performed annually mainly by women in Spain. / Al-Kasadi, MSS. (2014). Modeling the propagation of the consumption of two emergent businesses: Fitness Practice and Plastic Surgery [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39795 / TESIS