New DIETs: New Dietary Interventions Enhancing the Treatment for Weight Loss
Condition: Overweight; Obesity
MeSH terms: Overweight; Weight Loss
Study type: Interventional

Summary: 
      Several studies have shown differences in health-related outcomes by dietary pattern. These
      patterns have included those participants following vegan (no meat, poultry, fish, dairy, or
      eggs), vegetarian (no meat, poultry, or fish), pesco- vegetarian (no meat or poultry),
      semi-vegetarian (red meat and poultry ≥ 1 time/month and < 1 time/week), or omnivorous diets.
      These studies have shown that of these dietary patterns, vegans have the lowest BMIs, lowest
      prevalence of Type 2 diabetes, and lowest amount of weight gain over 5 years. In addition,
      vegetarians have significantly better metabolic risk factors as compared to non-vegetarians.
      While these initial observational studies have shown benefits to consuming more plant-based
      diets, there have been no randomized trials examining the differences in health outcomes
      among these dietary patterns. To begin exploring this research area, the investigators will
      conduct a pilot study which will randomize participants to one of the 5 dietary approaches.
      Participants (n=75) in the NEW DIETs Study will be recruited to follow their randomly
      assigned diet for 8 weeks and attend weekly sessions to learn about nutrition and cooking.
    

Detailed description: 
      This study involves five groups. Participants will be randomly assigned to one of these
      groups. All groups will receive information on a dietary approach aimed at losing weight. All
      groups will be asked to favor foods that are low fat and have a low glycemic index, which
      means they will be asked to favor foods that don't cause a quick rise in blood sugar (for
      example, choosing oatmeal over cornflakes for breakfast). All groups will also be asked to
      take a vitamin B-12 supplement each day of their choosing (can be a multivitamin).

      Participants who are eligible on the online screener will be contacted by phone to complete a
      few additional screening questions and invited to an orientation meeting.

      Below are the steps in the study:

        -  If participants are accepted into the study, participants will come to the study site
           (USC Public Health Research Center) to learn more about the study, have their weight and
           height measured, learn how to complete questionnaires online, and complete their consent
           form. This meeting will last approximately 1.5 hours.

        -  Participants will then complete some questionnaires that measure their diet and physical
           activity levels on a computer at home or other location where participants have
           computer/internet access. We will also ask participants to keep all their grocery and
           restaurant receipts during this time to bring back with participants to the next
           meeting.

        -  Participants will come back for a meeting to have their weight measured again and
           participants will find out their diet group assignment. Participants will receive a 1.25
           hour overview of the diet participants have been assigned to and be provided with
           materials on this diet.

        -  If participants are assigned to the vegan, vegetarians, pesco-, or semi-vegetarian
           diets, they will complete the following over the 8-week study:

             1. Participants will attend weekly meetings over 8 weeks.

             2. We will obtain their weight and collect online questionnaires at weeks 4 and 8.

             3. During the 8-week study, we will ask participants to complete an online weekly
                questionnaire which will assess if participants are following the diet and their
                weight. This will take approximately 5 minutes to complete.

        -  If participants are assigned to the omnivorous diet, they will only come in for meetings
           at baseline, 4 weeks, and 8 weeks.

             1. We will obtain their weight and collect online questionnaires at weeks 4 and 8.

             2. Participants will receive e-mailed lessons of their diet plan each week.

             3. During the 8-week study, we will ask participants to complete an online weekly
                questionnaire which will assess if participants are following the diet, and their
                weight. This will take approximately 5 minutes to complete.

             4. At week 8, participants will also be provided with information about the other 4
                diets in case participants would like to try these dietary patterns after the
                study.

        -  All diet groups will be asked to collect and turn in all grocery store and restaurant
           receipts for 2 weeks prior to the start of the intervention and for the 8 weeks during
           the study.

        -  At study completion (8 weeks), participants will receive an incentive for participating
           ($20).

        -  Participants in all groups will be asked to take a daily multivitamin (or other reliable
           source of vitamin B-12) over the course of the study. You are responsible for choosing
           and purchasing this.

        -  During the study, we will ask you to keep your physical activity levels constant (keep
           your levels the same as what you were doing at study entry).
    

Intervention name(s): Diet
Intervention type(s): Behavioral
Intervention description(s): Change in dietary intake
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: weight loss; obesity; overweight; diet