Inclusion Criteria:

- Age 25 to 65 years at beginning of study

- BMI between 20 and 38 kg/m2

- Fasting glucose < 126 mg/dl

- Blood pressure < 160/100 (controlled with certain medications)

- Fasting total blood cholesterol < 280 mg/dl

- Fasting triglycerides < 300 mg/dl

Exclusion Criteria:

- Presence of kidney disease, liver disease, gout, hyperthyroidism, untreated or
unstable hypothyroidism, certain cancers, gastrointestinal disease, pancreatic
disease, other metabolic diseases, or malabsorption syndromes

- Type 2 diabetes requiring the use of oral antidiabetic agents or insulin

- History of bariatric or certain other surgeries related to weight control

- Smokers or other tobacco users (during 6 months prior to the start of the study)

- Antibiotic use during the intervention or for 3 weeks prior to any intervention
period

- History of eating disorders or other dietary patterns which are not consistent with
the dietary intervention (e.g., vegetarians, very low fat diets, high protein diets)

- Volunteers who have lost 10% of body weight within the last 12 months or who plan to
initiate a weight loss program during the next 10 months

- Known (self-reported) allergy or adverse reaction to pistachios or other nuts

- Unable or unwilling to give informed consent or communicate with study staff

- Self-report of alcohol or substance abuse within the past 12 months and/or current
acute treatment or rehabilitation program for these problems (long-term participation
in Alcoholics Anonymous is not an exclusion)

- Other medical, psychiatric, or behavioral factors that in the judgment of the
Principal Investigator may interfere with study participation or the ability to
follow the intervention protocol