Traditionally, poultry farmers aimed to produce birds with high body weight and feed conversion ratio. However, in line with current developments, there are other traits that must be taken into account as well. These include producing poultry meat with lower body fat content and improving the nutritional quality of the poultry meat to appeal to consumer requirements. The interrelated importance of human diet and health status is an ancient subject. Human foods as a lifestyle factor is involved in the incidence of many types of diseases, such as cardiovascular diseases and cancer. Recent reports suggest that not only the quantity but also the composition of dietary fat is an important factor to prevent these metabolic diseases in human populations. It has been reported that some dietary fats are able to reduce lipid synthesis and increase fatty acid oxidation and diet-mediated thermogenesis. The outcome of this change is a superior animal product with lower fat content. There is evidence of dissimilar mechanisms of action of n-3 and n-6 fatty acids. Dietary fatty acids have various effects on cellular metabolism, and many of these effects are carried out through the alteration of gene expression. This review will focus on the control of body fat by gene expression in avians.