**1. Introduction**

Obesity is excess body weight for a given height, defined by a body mass index (BMI) ≥ 30 kg/m2 . In some Asian countries (e.g., Japan), the threshold to define obesity is lower (25 kg/m<sup>2</sup> ). Obesity is a major health problem worldwide associated with increased morbidity/mortality and high cost for the society. The prevalence of obesity has doubled in more than 70 countries since 1980. The number of adult subjects with obesity is around 700 million worldwide. Nearly 4 million subjects die each year from the consequences of obesity. The annual cost of obesity is more than \$2 trillion [1–3].

Management of obesity requires multidisciplinary approaches including diet, food supplement, exercise, behavior change, drug, medical device, gut microbiome manipulation, and surgery [1, 4–9]. The annual obesity treatment market is around \$6 billion. In the USA, among subjects with obesity, only 2% receive drug therapy and less than 1% who are eligible for bariatric surgery benefits from it. The reasons for these undertreatment rates are mainly related to adverse effects/complications and cost of drugs and bariatric surgery.

Medical devices available 100 years ago were limited to stethoscope, original medical X-ray imaging device, and electrocardiograph [10]. Over the past several decades, the number of medical devices has increased exponentially. Anti-obesity medical devices are positioned to bridge the gap between more conservative treatments (e.g., lifestyle) and more aggressive interventions (e.g., bariatric surgery). Compared to bariatric surgery, they have the advantage of being less invasive, easier to perform, and reversible. Anti-obesity medical devices are available upon prescription or as over-the-counter products.
