Walnut Pre‐Dinner Snack Reduces Meal‐time Hunger and Calorie Intake Among University Students

Abstract

Freshman‐15 is a phenomenon of first year university students enrolled in cafeteria meal plans resulting in weight gain due to new eating patterns and stress. Eating habits established at a young age continue into later adulthood and contribute to obesity. Walnuts are a nutrient dense snack that may improve weight control in middle to older aged adults. This study determined if a pre‐meal walnut snack alters hunger and satiety before and after a subsequent standardized meal, and meal‐time nutrient intake. Healthy university students (18.1 ± 0.5 years; 33 female and 3 male; BMI 23.6 ± 3.9) received a standard dinner (1760 Calories) with three treatments (90 minutes pre‐meal) in single crossover design: 1) Snack of 190 Cal (1oz) of walnuts (WS; Jugans regia), 2) Snack of 190 Cal of gummi candy (GS), or 3) No snack (NS; control) on three consecutive evenings. Visual analog scale (VAS) surveys were administered 5 minutes before and after dinner ingestion to measure sense of hunger, desire to eat, fullness, and intent to eat 30 minutes after study completion. Digital meal images were used to determine caloric and nutrient intake during the meal (LSM ± SE; Significance: P< 0.05). Pre‐meal VAS for desire to eat during the subsequent meal after WS, GS, and NS was 8.1 ± 0.5, 8.6 ± 0.5, and 9.3 ± 0.4 (WS<NS; GS<NS). Post‐meal desire to eat was not significant across treatments for WS, GS, and NS, 1.9 ± 0.3, 1.7 ± 0.2, and 1.8 ± 0.2. Pre‐meal sense of hunger for WS, GS, and NS were, 7.8 ± 0.2, 7.8 ± 0.2, and 8.8 ± 0.4 (WS>NS; GS>NS). Post‐meal sense of hunger for WS, GS and NS were, 1.6 ± 0.4, 1.3 ± 0.2, and 1.4 ± 0.2. Pre‐meal sense of fullness for WS, GS, and NS were 2.5 ± 0.4, 2.1 ± 0.3, and 1.2 ± 0.2 (W>NS; G>NS). Post‐meal sense of fullness for WS, GS, and NS were 8.5 ± 0.5, 9.2 ± 0.3, and 9.1 ± 0.4. Sense of intent to eat 30 minutes after study completion pre‐ or post‐meal time was not significantly affected by treatment. Calories consumed after WS, GS and NS were 982 ± 62, 1050 ± 61, and 1079 ± 61 (WS<GS; WS<NS; NS vs GS not significant). When snack calories were included, total meal calories consumed after WS, GS and NS were 1139 ± 75, 1184 ± 76, and 1095 ± 68 (WS<NS). Total fat intake (g) after WS, GS and NS was 43 ± 3, 46 ± 3, and 47 ± 3 (WS < GS and NS). Saturated fat intake (g) after WS, GS and NS was 15 ± 1, 16 ± 1, and 17 ± 1 (WS < NS). Cholesterol intake (mg) after WS, GS and NS was 105 ± 9, 113 ± 9, and 117 ± 9 (WS < NS). Sodium intake (mg) after WS, GS and NS was 1993 ± 158, 2150 ± 155, and 2181 ± 153 (WS < GS and NS). Protein intake (g) after WS, GS and NS was 37 ± 3, 40 ± 3, and 42 ± 3 (GS < NS). Fiber intake (g) after WS, GS and NS was 3.8 ± 0.3, 4.2 ± 0.3, and 4.2 ± 0.3 (WS<GS). Consumption of snacks (WS, GS and NS) prior to the standard dinner had no effect on meal carbohydrate intake (g) 108 ± 9, 114 ± 7, and 113 ± 8, or sugar intake (g) 34 ± 5, 33 ± 5, and 34 ± 5. Consumption of a walnut snack prior to dinner reduced hunger and desire to eat, and increased sense of fullness prior to a meal, associated with reduced meal‐time caloric and fat intake. These benefits were less pronounced following the isocaloric gummi candy snack. Consumption of a walnut snack 90 minutes prior to dinner may lead to long term improvements in weight management during later adulthood.Support or Funding InformationThis study funded by an unrestricted grant from the California Walnut Commission.