Meal times differ from culture to culture. These differences may influence energy regulation and, consequently, body weight. Current studies support the notion that not only "what" but also "when" the investigators eat may have a significant role in obesity treatment. Recently, it has been shown that eating the main meal of the day, lunch in Spain, late in the day is predictive of difficulty in weight loss and decreased insulin sensitivity. This project aims to study in a Mediterranean population the potential influence of genetics and food timing on obesity, metabolic syndrome and weight loss.