Factors influencing the reinforcing value of fruit and unhealthy snacks.

OBJECTIVE: The present study investigated the reinforcing value of healthy and unhealthy snack food in adolescents (n = 108, aged 14-16 years). Moderation by access to different foods, sex and the personality trait reward sensitivity is tested. METHODS: In a computerized Food Reinforcement Task, adolescents could earn portions of a healthy and an unhealthy snack following an identical progressive reinforcement schedule for both food types. Reinforcing value of food was indexed by the number of button presses for each food type. Participants were allocated randomly to two-order condition: fruit-snack versus snack-fruit. Reward sensitivity was assessed with the Dutch age-downward version of Carver and White's BIS/BAS scale. RESULTS: Results showed that the reinforcing value of an unhealthy snack is higher than that of fruit, with participants making more button presses for unhealthy snacks, M = 1280.40, SD = 1203.53, than for fruit, M = 488.04, SD = 401.45, F(1,48) = 25.37, p < 0.001. This effect is stronger in boys (ß = -1367.67) than in girls (ß = -548.61). The effect is only present in the snack-fruit condition, not in the fruit-snack condition, indicating that access to food moderates the effect of food type. There is no evidence for moderation by reward sensitivity. CONCLUSIONS: Results point to the importance of simultaneously increasing barriers to obtain unhealthy food and promoting access to healthy food in order to facilitate healthy food choices.

Development and validation of a quantitative snack and beverage food frequency questionnaire for adolescents.

BACKGROUND: A short, reliable and valid tool to measure snack and beverage consumption in adolescents, taking into account the correct definitions, would benefit both epidemiological and intervention research. The present study aimed to develop a short quantitative beverage and snack food frequency questionnaire (FFQ) and to assess the reliability and validity of this FFQ against three 24-h recalls. METHODS: Reliability was assessed by comparing estimates of the FFQ administered 14 days apart (FFQ1 and FFQ2) in a convenience sample of 179 adolescents [60.3% male; mean (SD) 14.7 (0.9) years]. Validity was assessed by comparing FFQ1 with three telephone-administered 24-h recalls in a convenience sample of 99 adolescents [52.5% male, mean (SD) 14.8 (0.9) years]. Reliability and validity were assessed using Bland-Altman plots, classification agreements and correlation coefficients for the amount and frequency of consumption of unhealthy snacks, healthy snacks, unhealthy beverages, healthy beverages, and for the healthy snack and beverage ratios. RESULTS: Small mean differences (FFQ1 versus FFQ2) were observed for reliability, ranking ability ranged from fair to substantial, and Spearman coefficients fell within normal ranges. For the validity, mean differences (FFQ1 versus recalls) were small for beverage intake but large for snack intake, except for the healthy snack ratio. Ranking ability ranged from slightly to moderate, and Spearman coefficients fell within normal ranges. CONCLUSIONS: Reliability and validity of the FFQ for all outcomes were found to be acceptable at a group level for epidemiological purposes, whereas for intervention purposes only the healthy snack and beverage ratios were found to be acceptable at a group level.

Using a gamified monitoring app to change adolescents' snack intake: the development of the REWARD app and evaluation design.

BACKGROUND: As the snacking pattern of European adolescents is of great concern, effective interventions are necessary. Till now health promotion efforts in children and adolescents have had only limited success in changing adolescents' eating patterns and anthropometrics. Therefore, the present study proposes an innovative approach to influence dietary behaviors in youth based on new insights on effective behavior change strategies and attractive intervention channels to engage adolescents. This article describes the rationale, the development, and evaluation design of the 'Snack Track School' app. The aim of the app is to improve the snacking patterns of Flemish 14- to 16-year olds. METHODS: The development of the app was informed by the systematic, stepwise, iterative, and collaborative principles of the Intervention Mapping protocol. A four week mHealth intervention was developed based on the dual-system model with behavioral change strategies targeting both the reflective (i.e., active learning, advance organizers, mere exposure, goal-setting, monitoring, and feedback) and automatic processes (i.e., rewards and positive reinforcement). This intervention will be evaluated via a controlled pre-post design in Flemish schools among 1400 adolescents. DISCUSSION: When this intervention including strategies focused on both the reflective and automatic pathway proves to be effective, it will offer a new scientifically-based vision, guidelines and practical tools for public health and health promotion (i.e., incorporation of learning theories in intervention programs). TRIAL REGISTRATION: NCT02622165 registrated November 15, 2015 on clinicaltrials.gov.