Do Weight Status and the Level of Dietary Restraint Moderate the Relationship Between Package Unit Size and Food Intake?
Condition: Overweight
MeSH terms: Overweight
Study type: Interventional

Summary: 
      The objective of this study is to determine the independent and combined effects of weight
      status and the level of dietary restraint on the relationship between package unit size and
      food intake.
    

Detailed description: 
      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.

      Specific Aims:

        1. Determine the effect of dietary restraint on the relationship between package unit size
           and food intake.

        2. Determine the effect of weight status on the relationship between package unit size and
           food intake.

        3. Determine the combined effect of weight status and dietary restraint on the relationship
           between package unit size and food intake.
    

Intervention name(s): Package Unit Size - Single Serving; Package Unit Size - Standard
Intervention type(s): Other; Other
Intervention description(s): Participants will receive a box of twenty-two, 0.9-oz. packages of pretzels. Participants will receive the box of pretzels in the lab on a Thursday or Friday and will take the box of pretzels home for a period of four days. Participants will bring back the box of pretzels to the lab on the following Monday or Tuesday (depending on the day of the initial receipt of pretzels).; Participants will receive a box of two, 10-oz. packages of pretzels. Participants will receive the box of pretzels in the lab on a Thursday or Friday and will take the box of pretzels home for a period of four days. Participants will bring back the box of pretzels to the lab on the following Monday or Tuesday (depending on the day of the initial receipt of pretzels).
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: normal weight; overweight; dietary restraint; package unit size; food intake