Table 2.

Description of included substitution studies

Reference	Study aims	Intervention type, comparator and duration	Outcome measurement	Main results
Chronic studies
Brauchla M, 2013 USA	To determine the effect of introducing two high-fiber snacks per day on gastrointestinal function as well as nutrient and food group intake in healthy children ages 7–11 yrs old Ages: 7-11 yrs Total n completed = 80	Cluster randomized-controlled prospective community-based intervention for 8 weeks. 1) Consume two high-fiber snacks per day (7 d/week, 10-12 g/d fiber). Each child also offered 8-ounce carton of skim milk at each snack occasion to provide fluids to prevent gastrointestinal distress. 2) Control: Usual snacks.	2 × 24 h dietary recalls	1) NS in mean (SD) macronutrient, fibre or micronutrient intakes between groups at the end of the intervention. 2) NS in mean (SD) wholegrain intake between groups at the end of the intervention (0.77 (1.0) servings/d vs. 0.56 (0.76) servings/d, P > 0.05). 3) Intake of mean (SD) total grains (6.30 (2.28) servings/d vs. 5.45 (1.58) servings/d), and sweets (0.55 (0.64) servings/d vs. 0.33 (0.37) servings/d, all P < 0.05) was higher in the intervention vs. control group.
Zaveri S, 2009 UK	To investigate the effect of incorporating a novel type of snack (almonds) and a conventional snack (cereal bars), on eating frequency, hunger rating, total energy intake, fasting glucose, insulin and lipid levels and anthropometric measures over a 12 week period in a sample of overweight Scottish men Ages: 25-50 yrs Total n completed = 36	Randomized trial for 12 weeks 1) Two cereal bars (30 g; high in carbohydrate, total 44 g carbohydrate). 2) Two packets of almonds (28 g; high in protein, total 11.8 g). 3) Control: No snacks and asked to continue habitual eating pattern.	1) 4 d unweighed diet diaries 2) Anthropometry	1) NS in intake of energy, protein, fat or sugar intake between groups after the intervention (P > 0.05). 2) NS between groups in body weight or waist:hip ratio (P > 0.05).
Acute studies
Flood J, 2006 USA	To examine the impact of increasing beverage portion size on beverage and food intake. Ages: 18-45 yrs Total n completed = 33	Cross-over study. Subjects came to the laboratory to eat lunch once a week for 6 weeks, for a total of six test sessions. Subjects ate a standard breakfast, and then lunch differed in portion size of beverage (same food). One of three beverages served in one of two portion sizes (360 g or 540 g): 1) Regular cola (150 cal/260 g; 250 kcal/540 g). 2) Diet cola (0 cal). 3) Water (0 cal).	Weighed food before and after eating	1) Subjects consumed more energy from the caloric beverage (regular cola) when served the large portion (151 ± 8 kcal) vs. the small portion (128 ± 4 kcal, P < 0.05). 2) Subjects consumed more water (380 ± 10 g) than regular cola (335 ± 11 g) and diet cola (298 ± 12 g), and more regular cola than diet cola (all P < 0.0001). 3) Food intake at lunch did not differ by either type or portion size of the beverage served (P > 0.05).
Rolls BJ, 2010 USA	To investigate the effects on food and energy intakes of varying the portion size and energy density of a vegetable that was added to a meal or substituted for other foods. Ages: 20-45 yrs (mean 27 yrs) Total n completed = 48 in the substitution study	Crossover design with repeated measures. Two studies: In both studies, a midday meal of a vegetable, grain, and meat served to participants once a week. Across the meals, the vegetable was increased in portion size (180, 270, or 360 g) and reduced in energy density (0.8 to 0.4 kcal/g). Substitution study: as the vegetable portion was increased, the amounts of the meat and grain decreased equally (i.e. the total amount of food served at the meal did not change).	Weighed food before and after eating	1) Increasing the portion of the vegetable from 180 to 270 g increased vegetable intake in both studies by a mean ± SE of 34 ± 4 g, P < 0.0001, equivalent to ~ ½ serving. 2) Doubling the portion of the vegetable (180-360 g) increased vegetable intake by 60 ± 5 g (49 ± 4 %), P < 0.0001, equivalent to ~ ¾ serving. 3) Reducing the energy density of the vegetable led to a small decrease in vegetable consumption (9 ± 3 g, P = 0.002). 4) Substitution study: intakes of the meat and grain decreased as the portion of the vegetable increased from 180 to 270 g; significant decrease in energy intake from energy-dense meat and grain as portion sizes decreased (40 ± 10 kcal; P < 0.0001).
Patel BP, 2013 Canada	To examine appetite and energy intake following ad-libitum consumption of an afterschool snack of raisins, grapes, potato chips, and chocolate chip cookies in children 8 to 11 yrs. Ages: 8-11 yrs (mean 10 yrs) Total n completed = 26	Within-subjects repeated measures design. Children were given: 1) Grapes (301 g) 2) Raisins (65 g) 3) Potato chips (38 g) 4) Chocolate chip cookies (45 g) to consume (within 15 min) as an afternoon snack.	Weighed food before and after eating	1) Mean ± SEM snack intake was lowest after raisins (228 ± 21 kcal) and grapes (177 ± 17 kcal) compared to potato chips (413 ± 20 kcal), however cookies was highest (505 ± 32 kcal, P <0.001). 2) Cumulative food intake was lowest after raisins (1099 ± 21 kcal) and grapes (1049 ± 17 kcal; P < 0.001) compared to potato chips (1284 ± 20 kcal), however, cookies was highest (1376 ± 32 kcal; P <0.001). 3) Neither energy density nor volume predicted the effect of the snack on cumulative energy intake (Energy densities of raisins (3.04 kcal/g), chips (5.58 kcal/g), and cookies (4.68 kcal/g) were higher than for grapes (0.69 kcal/g), but grapes and raisins had similar effects on cumulative food intake.

n number of participants, NS not significant, SD standard deviation, SEM standard error of the mean, yrs years of age