The purpose of this study is to evaluate the effects of pistachio snacking on metabolic flexibility (at rest, during exercise, and in post-exercise recovery) in healthy overweight and obese adults. Secondary goals include evaluating effects on changes in diet quality, sleep characteristics, physical activity, and hormonal health in women. In randomized order, participants will complete four days of pistachio snacking and four days of normal dietary habits (control). For both conditions, primary outcomes of resting substrate metabolism, metabolic flexibility during exercise, and post-exercise substrate metabolism will be measured pre-post intervention via indirect calorimetry. Secondary outcome of diet quality (kcal, carb, fat, protein) will be measured pre-post intervention via diet log. Exploratory outcomes of daily physical activity (steps, intensity), nightly sleep characteristics (quantity, quality, latency, efficiency), and daytime sleepiness and hunger.
Males and Females
Age: 25-45 years
Overweight or obese (BMI=25.0-34.9 kg/m²)
Poor sleep quality (Pittsburgh Sleep Quality Index ≥ 5)
Allergies to nuts, especially tree nuts
Has a pacemaker
Following a diet that is restrictive or eliminates certain food group/types
Self-repoted health or disease state that may influence study outcomes, including known metabolic or endocrine disorder (e.g. prediabetes, type 1 or type 2 diabetes, or polycystic ovary syndrome), cardiovascular diseases, neuromuscular disorders, musculoskeletal disorders; current or recent history of cancer/cancer treatment (within the past year)
Crossover
Pistachio
Other interventionRoasted, lightly salted, pistachio kernels (no shell)
resting metabolism
resting metabolic rate (RMR) and substrate utilization (RER) via indirect calorimetry
exercise metabolic flexibility
substrate metabolism (RER; indirect calorimetry) throughout a submaximal, graded exercise test
post-exercise metabolism
Energy expenditure and substrate metabolism (RER) measured at 0, 30, 60, 90min post-exercise via indirect calorimetry
Caloric Intake
Average calorie intake (kcal) via 24-hr diet record
Carbohydrate Intake
Average carbohydrate intake (grams) via 24-hr diet record
Protein Intake
Average protein intake (grams) via 24-hr diet record
Fat Intake
Average fat intake (grams) via 24-hr diet record
Physical Activity
Daily (24-hr) steps and intensity minutes via wrist activity tracker
Sleep Quantity
Nightly sleep quantity (total time spent asleep; minutes) via wrist worn activity tracker.
Sleep Quality
Nightly sleep quality (time spent in deep sleep (minutes), REM sleep (minutes), and light sleep (minutes)) via wrist worn activity tracker.
Daytime sleepiness
Subjective likelihood of falling asleep in various situations via Epworth Sleepiness Scale. In this eight question survey, questions are rated on a scale of 0 (very unlikely) to 3 (very likely), with a total score of 0-9 indicating low daytime sleepiness, 10-15 indicating moderate daytime sleepiness, and 16-24 indicating severe daytime sleepiness.
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University of South Carolina
Lead sponsor
American Pistachio Growers
Collaborator
