**1. Introduction**

Obesity prevalence rapidly increases in the world. A recent epidemiological study reported that an estimated 1.46 billion adults were overweight (body mass index (BMI) > 25 kg/m2 ), and 502

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

million adults were obese (BMI > 30 kg/m2 )[1]. Such global obesity pandemic has serious health problems. Obesity is an established risk factor for type 2 diabetes, cancers, and cardiovascular diseases (CVD), which cause large disease burden in many low-income countries as well as high-income countries [2]. Meanwhile, physical inactivity is also a global health problem responsible for the risk increment of non-communicable diseases such as type 2 diabetes, coronary heart disease, and breast and colon cancers [3]. If physical inactivity disappears, the life expectancyofhumanswouldriseby0.68years [3].TheAmericanCollegeofSportsMedicine and the American Heart Association have recommended that obese individuals engage in moderate-intensity aerobic physical activity for at least 30 minutes for 5 days per week, or vigorous-intensity aerobic physical activity for at least 20 minutes for 3 days per week [4]. However,obese individualshaveusuallyphysical, social,andpsychologicalbarriers toperform the recommended level of physical activity [5], it is quite difficult to resolve these two major health problems worldwide; obesity and physical inactivity pandemic. Nevertheless, a large number of clinical studies investigating the effects of physical activity on obesity have been conducted, and the evidence has been accumulated. This review is aimed at summarizing the current literature related to physical activity and obesity, and evaluating the effects of physical activity on obesity. This review will help clinicians, researchers, and obese individuals in the managementofobesity.Inadditiontothe literature review,the authorfocusesonthe association between non-exercise activity thermogenesis (NEAT) and obesity to explore the possibility of applying NEAT to the treatment of obesity.
