Abstract—Excess body weight has reached epidemic proportions globally, with more than 1 billion adults being either overweight or obese. Increase in the body weight has been observed across all age groups. Excess body weight is a multi-factorial and heterogeneous condition that results from alterations of various genes. The inheritance pattern of obesity is thus complex, and environmental factors play an important role in promoting or delaying its development. Even though genetic contribution to inter-individual variation in common obesity has been estimated at 40-70%, the search for obesity susceptibility genes has been not achieved to a large extent. This article reviews progress made in the field of genetics for the understanding of heritability of body weight with an emphasis on established overweight or obesity susceptibility loci identified through candidate gene, genome wide linkage and genome-wide association studies. Although it is not clearly understood the strength of the genetic effects on obesity, it is evident that human adiposity and a propensity towards weight gain is influenced by genes.