The estimated prevalence of obesity among adults in 2007-2008 was 33.8% and the combined estimated prevalence of overweight and obesity was 68.0% [1]. Although there are no clear reasons for the current obesity epidemic, there is a general consensus that environmental dietary factors, such as package unit size, encourage excessive food intake and positive energy balance [2, 3]. It is believed that the package unit size of food indirectly influences food intake by impacting the accuracy of consumption monitoring [2, 4]. Large packages decrease the accuracy of consumption monitoring by making it difficult to assess how many servings have been consumed in one sitting, while small single-serving packages can increase the accuracy of consumption monitoring by providing a clear definition of what a standard serving is and how much one has consumed [2, 4, 5]. Therefore, it has been proposed that small, single-serving packages of snack foods may help reduce energy intake [4, 5]. To date, limited studies have been conducted in this area and the results are inconsistent [4-9]. Mixed results could be related to differences in participant variables, specifically weight status and level of dietary restraint (a term that refers to the amount of control exerted over food intake) [4, 9]. These individual characteristics may interact with food package unit size to influence one's food intake [2, 4]. Overweight individuals or restrained eaters may more closely monitor the volume of food they consume as compared to normal weight or unrestrained eaters [4, 9]. The [smaller] size of food packaging may aid in monitoring food consumption and thus, influence how much food is consumed in overweight and/or restrained eaters [2, 4]. Therefore, the objective of this study is to determine if weight status and the level of dietary restraint moderate the relationship between package unit size and food intake.