Human food intake is driven by necessity, but modern industrialized societies are characterized by food surfeit and an increasingly ‘obesogenic’ environment. This environment tends to discourage energy expenditure and to facilitate energy intake. The amount eaten in any given eating episode depends less on internal need state and more on environmental contextual factors such as the availability of highly-palatable energy-dense foods. In addition, the process of satiation can easily be disrupted by the introduction within a meal of different foods (variety effect), the presence of others (social context) and competing tasks (distraction). Properties of ingestants such as alcohol promote food intake and characteristics of individuals make them more or less susceptible to situational cues to overeat. In the present review the role of each of these environmental factors in promoting overconsumption is considered and the extent to which these factors might contribute to long-term weight regulation is discussed.