**1. Introduction**

Overweight and obesity have reached epidemic proportions. The World Health Organization (WHO) estimates that approximately 2.5 billion adults are overweight, and at least 700 million are obese [1]. Overweight and obesity are linked to more deaths worldwide than underweight. As the number of people with obesity rises, the prevalence of obesity-related comorbidities, such as diabetes, hypertension, hyperlipidemia, obstructive sleep apnea, and fatty-liver disease is rising as well. Numerous strategies have been employed in the treatment of obesity; however, most people do not reach or sustain such significant weight loss with lifestyle intervention, composed of diet, exercise, and behavior modification, alone. Bariatric surgery has emerged as the most effective treatment for obesity in the long term and is associated with a significant decrease in obesity-associated comorbidities [2, 3]. However, current bariatric surgical procedures are accompanied by a substantial risk of complications. These potentially serious complications during and following the invasive and irreversible surgical procedures are incontrovertible. In addition, only a small proportion of obese patients actually undergo bariatric surgery. With this in mind, there exists a critical gap in the treatment of obesity for those not qualifying for bariatric surgery or those who do not wish to pursue bariatric surgery because of a multitude of reasons such as the associated risks, morbidity, and costs. Thus, there is a strong need for new and less invasive, safer and preferably reversible alternatives to bariatric surgical procedures. Therefore, new techniques to achieve weight loss in obese patients who claim to be as effective as surgery but safer have been developed. In addition, these therapies may be beneficial earlier on in the

onset of obesity. In this chapter, we aim to present the current state of field regarding investigational procedures in the treatment of obesity that are already available in clinical practice or in advanced stages of development. This chapter outlines their potential mechanism of action and their safety and efficacy in clinical practice, by reviewing the current literature.
