Inclusion Criteria:

• Age 40-65 years
• BMI 25 to 40 kg/m2
• HbA1c 5.7-6.4%
• Low habitual intake of peanut butter (<0.5 Tablespoons/day on average)
• Have a smartphone device or be willing to use one provided by the study

Exclusion Criteria:

• Hemoglobin <13.2 g/dL for men or < 11.7 g/dL for women at screening
• Fasting triglycerides >350 mg/dL at screening
• LDL-cholesterol ≥190 mg/dL assessed by the Martin-Hopkins equation at screening
• ≥10% change in body weight within the 6 months prior to enrollment
• Blood pressure >140/90 mmHg at screening
• Diagnosed type 1 or type 2 diabetes
• Takes any (prescription or over-the-counter) anti-hypertensive, lipid-lowering, glucose-lowering or body weight altering drugs
• Intake of supplements that affect the outcomes of interest (i.e., lipids, blood pressure, glucose, body weight, and microbiome) and are unwilling to cease during the study period.
• Unwilling to refrain from starting to take any supplements, vitamins, nutritional products, or health foods that are not prescribed by a doctor for the duration of the study
• Self-reported history of diagnosed liver, kidney, or autoimmune disease
• Self-reported history of a prior cardiovascular event (e.g., stroke, heart attack)
• Self-reported history of diagnosed neurological disease (e.g. Alzheimer's Disease, Parkinson's Disease, Multiple Sclerosis)
• Current pregnancy or intention of pregnancy within the next 12 months
• Lactation within the prior 6 months
• Peanut allergy/intolerance/sensitivity/dislike
• Antibiotic use within the prior four weeks
• Oral steroid use within the prior four weeks
• Use of tobacco or nicotine-containing products within the past 6 months
• History of cancer at any site within the past 10 years (eligible if ≥10 years without recurrence) or non-melanoma skin cancer within the past 5 years (eligible if ≥5 years without recurrence)
• Participation in another clinical trial within 60 days of baseline
• Currently following a restricted or weight-loss diet
• Prior bariatric surgery
• Intake of >14 alcoholic drinks/week and/or not willing to avoid alcohol consumption for 48 hours prior to test visits
• Does not speak and/or understand English
• Unwilling to refrain from donating blood and/or plasma during the study
• Weight <110 lb
• Unwilling to contact study staff before enrolling in other health-related research and avoid participating in any research that may interfere with this study
• For individuals taking thyroid medication: abnormal thyroid stimulated hormone (TSH) concentration, or change in dose of thyroid medication within the last 6 months
• Principal Investigator discretion related to the potential participant's ability to adhere to the study requirements, including being able to come to attend visits