Obesity is a pandemic problem worldwide. Dietary polyphenolic compounds show promise in preventing obesity. Resveratrol (RSV), one of the most extensively studied polyphenol compounds, has been shown to exert anti-obesity effects in various animal studies and also in several human studies. The fat-lowering effects of RSV may result from its ability to inhibit adipogenesis, suppress lipogenesis, stimulate lipolysis, promote apoptosis and increase fatty acid oxidation and thermogenesis; as well as the recently demonstrated induction of the browning of white adipose tissue. These anti-obesity effects of RSV likely depend on its ability to activate AMP-activated protein kinase, a key enzyme regulating cellular energy metabolism. Consumption of fruits such as berries, grapes and nuts, which contain high levels of RSV and other polyphenols, might help to reduce obesity.