The purpose of the Get Fit, Be Fit Study is to examine the effect of incorporating pistachios in an intensive 4-month cognitive-behavioral weight loss intervention in overweight and obese men and women, to examine effects on metabolic factors, and to monitor and examine changes in dietary intake and food choices during the intervention, in a randomized controlled study.

This study investigates whether pistachios help to promote weight loss and improve metabolic and cardiovascular disease risk factors in 100 overweight or obese men and women who are participating in a 4-month behavioral weight loss intervention. Participants will be assigned to a cognitive-behavioral weight loss intervention and will be provided either general dietary advice as a component of the behavioral curriculum or prescribed an individualized pistachio-enriched reduced-energy diet plan. The pistachio-enriched diet will prescribe 42 g/day of pistachios, or approximately 13-20% (averaging 18%) of energy intake across a range of 1200-1800 kcal/day. Dietary intake will be assessed at three time points (baseline, one month, and four months) to examine changes in dietary intake and food choices that may be indicative of compensatory intake in response to regular nut consumption. Results from this study will contribute to understanding the role of pistachios in weight control, including further knowledge of the metabolic factors linked to chronic disease, and will expand knowledge of how pistachios in the diet may contribute to the prevention and management of obesity.

Inclusion Criteria:

• Men and Women who reside in the San Diego area
• Age 21 and older
• BMI ≥ 27.0 kg/m2 and ≤40 kg/m2
• No known allergy to tree nuts
• Non-diabetic
• Non-smoker
• Willing and able to participate in clinic visits, group sessions, and telephone and Internet communications at specified intervals
• Able to provide data through questionnaires and by telephone
• Willing to maintain contact with the investigators for 6 months
• Willing to allow blood collections
• Capable of performing a simple test for assessing cardiopulmonary fitness
• Willing and able to be physically active

Exclusion Criteria:

• Inability to participate in physical activity because of severe disability
• Inability to restrict consumption of nuts for four months
• History or presence of a co-morbid disease for which diet modification and increased physical activity may be contraindicated
• Self-reported pregnancy or breastfeeding or planning a pregnancy within the next year
• Currently actively involved in another diet intervention study or organized weight loss program
• Having a history or presence of a significant psychiatric disorder or any other condition that, in the investigator's judgment, would interfere with participation in the trial.
• Prior to enrollment
• Subjects will be screened for diabetes and considered ineligible with a fasting blood glucose ≥125 mg/dL.