Examining the Effects of Juice Fasting

Up to 30 participants will be enrolled in the study and will be randomized into one of the three arms: the "juice fasting" arm, the "juice plus ad hoc" arm, and the "caloric restriction" arm. Participants will come into the lab for an initial visit, during which they will complete questionnaires on their usual diet and demographics and will be informed about their assignment to one of the three arms. In all three arms, the three-day diet intervention will be preceded and followed by three days of self-conducted elimination diet. The pre-intervention diet will encourage participants to eat a healthy, light diet for three days (basic instructions: eat only fresh raw or cooked fruits and vegetables (preferably organic), whole grains and eggs; drink 8 glasses of water a day; avoid or eliminate alcohol, caffeine, sugar, processed foods, dairy, red meat, and gluten). The post- intervention diet will instruct participants to gradually return to eating solid foods, and limit strenuous exercise (basic instructions: follow a diet similar to the pre-intervention elimination diet; day 1 after the intervention: eat fruits \& green vegetables, and drink 8 glasses of water; day 2 add in: nuts, gluten-free grains like whole oats, quinoa, or brown rice; day 3 add in: organic meats, fish, \& gluten-containing grains). Biological samples and self-reported outcomes will be collected at four time points: baseline (prior to the first elimination diet period), pre-intervention (after the elimination diet and before the three-day intervention), post-intervention (after the intervention), and 14-day post- intervention. At each time point, participants will complete questionnaire on quality of life (PROMIS - Global Health Scale, which is an NIH measure on an individual's' overall physical and psychological well-being; see appendix) and collect their stool samples. Participants will be provided self-administered tool kits and be taught how to collect the stool sample at their first lab visit. At each of the four time points, the research assistant will coordinate the collection of cheek swabs, saliva samples, and blood spot samples. Biometrics will also be collected at each time point (weight, waist circumference, and blood pressure). Over the course of the study, participants will be instructed to keep a diet diary days one through nine to record their daily dietary intake. During the intervention period, the research team will also contact the participants for daily check-ins. Participants will not need to record diet data for the remaining 11 days of the post-intervention period. At the conclusion of the study, participants will bring back the final biological samples (stool wipe and saliva), provide the set of samples, and be debriefed about the purposes of the study. The biological samples collected will then be processed and assayed for microbiome, methylation, inflammatory markers, and glycemic markers.