Effects of Pecan Nut Snacks v Equicaloric Snacks on Appetite, Food Intake, Metabolism, Hormones and Biomarkers

This is a within-subjects crossover study that examines subjective appetite, food intake, hormone and metabolic responses to consumption of mid morning snacks of pecan nuts as compared to an iso-caloric amount of tortilla chips. Pecans are high in fat and calories and low in carbohydrate by weight, while tortilla chips are mostly carbohydrate and essentially devoid of fat. These two very different nutrient profiles should elicit different metabolic and biomarker responses. The study aims to determine whether these treatments also elicit different subjective appetite and food intake responses. Participants will be healthy volunteers with overweight and obesity, a population that may be seeking healthy snacking options that are satisfying and satiating.

This is a randomized, two condition, crossover study in healthy individuals with overweight and obesity examining the effect of a mid-morning snack of pecans vs. a low fat savory snack on appetite, energy expenditure, blood biomarkers of appetite and metabolism and ad libitum food intake at lunch. Twenty-four participants will be enrolled and studied on two test days with at least one week washout in between. On test days, participants will have baseline measures of appetite (by Visual Analogue Scale (VAS)), blood hormones and substrates, and energy expenditure and fuel oxidation (Resting Metabolic Rate (RMR), by indirect calorimetry) taken just prior to consuming a standardized 300 kcal breakfast. VAS measures will be taken at 20, 30, 60, 90 and 120 min following the meal and RMR will be measured for 20 min after eating. A mid-morning snack of either 250 kcal of pecans or lightly salted tortilla chips will be consumed and VAS and blood measures will be taken at 20, 30, 60, 90 and 120 min following the snack and RMR will be measured for 20 min after eating. Participants will be given an ad libitum lunch meal and VAS and blood measures will be taken at 20, 30, 60, 90 and 120 min following the lunch and RMR will be measured for 20 min after eating. Blood will be analyzed for glucose, insulin, free fatty acids, triglycerides, ghrelin, leptin, PYY, and GLP-1. Two hypotheses will be examined: 1. pecans will provoke greater feelings of fullness and reduced hunger after the snack and lunch meal consumption (on either a calorie per calorie or volume basis) as compared to the tortilla chip snack, and 2. the pecan snack will provoke greater responses of satiety hormones compared to tortilla chips. Post-snack and lunch energy expenditure and fat oxidation will also be compared between treatments as an exploratory aim.

Eligibility Criteria:
Inclusion Criteria:

1. 35 adult men and women
2. all ethnic groups
3. ages 20-50,
4. BMI 27-35,
5. habitually eat breakfast,
6. willing to eat the test snacks and other foods offered,
7. weight stable for the last 6 months
8. willing to consent and adhere to the test procedures and schedule

Exclusion Criteria:

1. nut allergies,
2. uncontrolled thyroid disorders,
3. diabetes mellitus,
4. eating disorders,
5. pregnant, or planning to become pregnant during the study,
6. lactating,
7. uncontrolled hypertension,
8. active dieting
9. intensive physical activity training regimen (\>300 min/wk exercise),
10. medical history or current medication that may affect study outcomes per study PI discretion
11. consuming pecans on a regular basis
12. unable to lie still with a clear hood over their head for the measurement of energy expenditure