All subjects will complete a 49-day, multi-phase feeding study to evaluate the effect of pea fiber supplementation on gut community structure and features of host biological state (plasma proteome/ metabolome). Subjects will be asked to continue to consume their habitual diet (free diet phase) for 4 days prior to being provided with a diet high in saturated fat (HiSF) and low in fruits and vegetables (LoFV) in the form of packed-out meals and snacks to consume for the following 45 days. Ten days after starting to consume the HiSF-LoFV diet, subjects will supplement their diet with pea fiber for a total of 21 days; the energy contribution from the HiSF-LoFV diet will be reduced accordingly to maintain energy needs during this time. After completing the pea fiber supplementation phase of the study subjects will revert back to consuming the HiSF-LoFV only diet for the final 14 days. Stool, urine and blood will be sampled periodically throughout.

Inclusion Criteria:

• BMI 25.0-35.0 kg/m²
• Presence of B. vulgatus and B. thetaiotaomicron each at greater than 0.01% relative abundance

Exclusion Criteria:

• Previous bariatric surgery
• Significant organ system dysfunction (e.g. diabetes, severe pulmonary, kidney, liver, or cardiovascular disease)
• Cancer or cancer that has been in remission for less than 5 years
• Major psychiatric illness
• Inflammatory gastrointestinal disease
• Pregnant or lactating women
• Use of medications that are known to affect the study outcome measures
• Use of medications or supplements known to affect composition of the gut microbiota within the last 30 days (e.g. antibiotics)
• Bowel movements less than 3 times per week
• Vegans, vegetarians, and those with allergies, aversions, or sensitivities to foods provided in the study
• Persons that are not able to grant voluntary informed consent
• Persons who are unable or unwilling to follow the study protocol or who the research team deems not an appropriate candidate for the study.