Obesity has been designated as a global epidemic by WHO as its prevalence has increased at an alarming rate in the last few decades worldwide. It is a risk factor for diabetes, hypertension, cardiovascular problems, etc. The contribution of genes to the development of obesity was confirmed in late twentieth century. The concept of monogenic obesity came with the identification of leptin, and mutations in its gene, followed by the discovery of more single gene mutations. However, the recent explosion of obesity could not be explained on the basis of these rare mutations and it was after the first genome-wide association study in 2007 that made possible the identification of different effect size variants in many candidate and non-candidate genes acting in a quantitative way to add to body weight. These studies laid down the basis for polygenic cause of common forms of obesity. The role of epigenetic regulation in the modulation of energy regulation pathway was another important explanation put forward in the latter half of the past decade. Taking into account the quantitative contribution of different variants has given the concept of obesity risk scoring in order to score individuals into different risk groups so as to decide for treatment options.