I-PREGNO - prevention of unhealthy weight gain and psychosocial stress in families during pregnancy and postpartum using an mHealth enhanced intervention: a study protocol of two cluster randomized controlled trials.

BACKGROUND: The transition to parenthood represents a critical life period with psychosocial, and behavioral changes and challenges for parents. This often increases stress and leads to unhealthy weight gain in families, especially in psychosocially burdened families. Although universal and selective prevention programs are offered to families, specific support often fails to reach psychosocially burdened families. Digital technologies are a chance to overcome this problem by enabling a low-threshold access for parents in need. However, there is currently a lack of smartphone-based interventions that are tailored to the needs of psychosocially burdened families. AIMS: The research project I-PREGNO aims to develop and evaluate a self-guided, smartphone-based intervention in combination with face-to-face counseling delivered by healthcare professionals for the prevention of unhealthy weight gain and psychosocial problems. The intervention is specifically tailored to the needs of psychosocially burdened families during the pregnancy and postpartum period. METHODS: In two cluster randomized controlled trials in Germany and Austria (N = 400) psychosocially burdened families will be recruited and randomized to i) treatment as usual (TAU), or ii) I-PREGNO intervention (self-guided I-PREGNO app with counseling sessions) and TAU. We expect higher acceptance and better outcomes on parental weight gain and psychosocial stress in the intervention group. DISCUSSION: The intervention offers a low cost and low-threshold intervention and considers the life situation of psychosocially burdened families who are a neglected group in traditional prevention programs. After positive evaluation, the intervention may easily be implemented in existing perinatal care structures in European countries such as Germany and Austria. TRIAL REGISTRATION: Both trials were registered prospectively at the German Clinical Trials Register (Germany: DRKS00029673; Austria: DRKS00029934) in July and August 2022.

Dietary intake, physical activity and sedentary behavior and association with BMI during the transition to parenthood: a prospective dyadic study.

Introduction: Little is known on how diet, physical activity (PA) and sedentary behavior (SB) changes during pregnancy and after childbirth in primiparous couples. Moreover, it is unclear how potential behavioral changes are associated with changes in BMI. This study examined changes in diet, PA and SB, and their association with changes in BMI in couples transitioning to parenthood. Methods: Dietary intake (FFQ), PA, SB (both Actigraph GT3X accelerometers) and BMI of women and men were assessed at 12 weeks of gestation, 6 weeks and 6 months postpartum. Data were analyzed using dyadic longitudinal data analyses techniques. Results: In women, a decrease in fruit intake, an increase in alcohol intake, an increase of light-intensity PA, and a decrease in SB were observed from the beginning of pregnancy up to 6 months postpartum. Decreases in fruit intake between 6 weeks and 6 months postpartum was associated with increases in BMI. Men did not show significant dietary changes, while an increase in light-intensity PA and a decrease in moderate-to-vigorous PA (MVPA) was observed at 6 months postpartum when compared to 12 weeks of gestation. Paternal increases in "avoidance food group" intake were associated with increases in BMI between baseline and 6 weeks postpartum. No associations of changes in BMI and changes in PA and SB were found. Discussion: Not only mothers but also fathers experienced unfavorable changes in lifestyle during the transition to parenthood, with impact on BMI changes. This highlights the need to monitor unhealthy changes in lifestyle and body weight in both parents when expecting a child and after childbirth. Clinical trial registration: Clinicaltrials.gov, NCT03454958.

Changes in maternal and paternal body composition during the transition to parenthood (TRANSPARENTS).

OBJECTIVE: The transition to parenthood might negatively influence health-related behavior and can result in increased adiposity. The aim of this study was to investigate how body composition in mother-father dyads changes from pregnancy up to 6 months post partum. METHODS: Anthropometrics were collected from 144 nulliparous couples at 12 weeks of gestation (PG12) and 6 weeks (PP6WK) and 6 months (PP6M) post partum. A longitudinal dyadic confirmatory factor analysis model was used to analyze changes in body composition. Body composition was treated as a latent variable using BMI, body fat percentage, and waist circumference as indicators. RESULTS: For women, latent means increased at 6 weeks post partum (PP6WK - PG12: +1.115, SE: 0.117, p < 0.001), decreased again at 6 months post partum (PP6M - PP6WK: -0.368, SE: 0.107, p < 0.001), but remained above baseline levels (PP6M - PG12: +0.747; SE: 0.115, p < 0.001). For men, the latent means at follow-up were higher than at baseline (PP6WK-PG12: +0.370, SE: 0.075; PP6M-PG12: +0.366, SE: 0.084, both p < 0.001). CONCLUSIONS: Increases in latent means correspond to unfavorable changes in BMI, body fat percentage, and waist circumference. These changes were observed from the beginning of pregnancy up to 6 months post partum. Weight management for both women and men during pregnancy and the early postpartum period is recommended and fathers should be included in pre- and postnatal standard care.

Association between perceived partner support and lifestyle in mother-father dyads expecting a first child.

Background: A healthy lifestyle during pregnancy is important for the health of mother and child. However, unfavorable physical activity (PA) and dietary changes are observed in pregnant women and their partner. Partner's influence on lifestyle has been reported by expectant women and men. The first aim was to analyze associations between perceived partner support on expectant parents own as well as their partner's moderate-to-vigorous intensity PA (MVPA) levels and dietary intake. Secondly, this study aimed to investigate intra-couple associations of MVPA, dietary intake and perceived support. Methods: A total of 152 heterosexual couples were recruited between week 8 and 10 of gestation by means of convenience sampling. Objective anthropometric and 7-day MVPA measurements were performed at 12 weeks of gestation. An online questionnaire was used to assess dietary intake, perceived partner support and socio-demographic characteristics. An Actor-Partner Interdependence Model for distinguishable dyads was constructed to examine the relationship between perceived partner support and both own's (i.e., actor-effect) and the partner's (i.e., partner-effect) MVPA levels, intake of fruits and vegetables, and an "avoidance food group." Results: For pregnant women, perceived support from their partner was significantly associated with women's own MVPA levels (i.e., actor-effect; estimate = 0.344, SE = 0.168, p = 0.040) as well as the MVPA levels of the men (i.e., partner-effect; estimate = 0.717, SE = 0.255, p = 0.005). No significant actor- nor partner-effects were found for the expectant fathers. For none of the sexes significant actor-effects were found for fruit/vegetables and "avoidance food group" intake. For pregnant women, there was a positive partner-effect for fruit and vegetable intake (estimate = 7.822, SE = 1.842, p < 0.001) and a negative partner-effect for the "avoidance food group" intake (estimate = -16.115, SE = 3.629, p < 0.001). Positive correlations were found for perceived MVPA support (r = 0.40, p < 0.001), MVPA levels (r = 0.24, p = 0.007) and food intake from the "avoidance food group" (r = 0.28, p = 0.005) between partners. Conclusion: This study shows that male partners can act as significant facilitators for women. Partners may be an important target when promoting MVPA during pregnancy. Additionally, supportive couples seem to strengthen each other in keeping a healthy lifestyle in early pregnancy. These results justify couple-based interventions in the promotion of a healthy lifestyle during the transition to parenthood. Clinical trial registration: Clinicaltrials.gov, identifier: NCT03454958.

Recommendations for the Development of Family-Based Interventions Aiming to Prevent Unhealthy Changes in Energy Balance-Related Behavior during the Transition to Parenthood: A Focus Group Study.

Feasible interventions addressing unhealthy changes in energy balance-related behavior (EBRB) during pregnancy and early postpartum are needed. This study identified the needs and wishes of expecting and first-time parents concerning EBRB interventions during the transition to parenthood. Thirteen focus group discussions (n = 74) were conducted. Couples provided information about whether an intervention targeting unhealthy EBRB changes during pregnancy and postpartum would be acceptable, how such an intervention should look like, and in which way and during which period they needed support. Guided by the TiDIER checklist, all quotes were divided into five main categories (i.e., 'what', 'how', 'when and how much', 'where', 'for and from whom'). Interventions should aim for changes at the individual, social, environmental and policy levels. The accessibility and approach (indirect or face-to-face) together with communicational aspects should be taken into account. A focus should go to delivering reliable and personalized information and improving self-regulation skills. Interventions should be couple- or family-based. Authorities, healthcare professionals, the partner and peers are important sources for intervention delivery and support. In the prevention of unhealthy EBRB changes around childbirth, the involvement of both parents is needed, while health care professionals play an important role in providing personalized advice.

The influence of parental body composition and lifestyle on offspring growth trajectories.

BACKGROUND AND OBJECTIVES: Parental body composition, physical activity (PA) and sedentary time (ST) have been linked with offspring body weight and health. However, independent contributions of body composition, PA and ST of both parents on growth trajectories of their offspring, taking into account sex differences, has not been investigated. METHODS: A total of 114 mother-father-child triads were included for analyses. Parental weight, height, PA and ST were objectively measured at 12 weeks of gestation. Gestational weight gain (GWG) and birthweight and -length were obtained from medical records. Offspring weight and length were measured repeatedly until 1 year of age. Longitudinal linear mixed models, stratified by offspring sex, were used to analyse the association between parental characteristics and offspring growth. RESULTS: GWG (positive association), maternal moderate-to-vigorous PA (negative association) and paternal ST (positive association) were associated with weight trajectories in girls but not in boys. Parental characteristics were not associated with offspring length trajectories. CONCLUSIONS: This study highlights the contribution of parental lifestyle characteristics on weight trajectories of their daughters during the first year of life. The paternal impact stresses the need to further investigate health behaviours of expecting fathers in relation to offspring health. Family-based interventions are needed with a focus on increasing PA and limiting ST in both parents.

Determinants of Changes in Women's and Men's Physical Activity and Sedentary Behavior across the Transition to Parenthood: A Focus Group Study.

BACKGROUND: Becoming a parent may cohere with drastic changes in physical activity (PA) and sedentary behavior (SB). A clear understanding of determinants of changes in PA and SB during pregnancy and postpartum is needed to facilitate the development of tailored family-based interventions. METHODS: Thirteen focus group discussions targeting determinants of changes in PA and SB behavior were conducted, involving a total of 74 expecting and first-time parents. A semi-structured question guide was used to facilitate the discussions. RESULTS: Four main levels of determinants were identified: the individual (including psychological, situational and biological determinants), interpersonal, environmental and policy level. Some determinants were mentioned to be a barrier (e.g., "barriers to self-care") while others were a facilitator (e.g., "weight control"). Determinants were related to both PA and SB and applicable during pregnancy as well as postpartum (e.g., "self-regulation"), or only related to one behavior and/or one period (e.g., "feeding baby"). Some were described by both parents (e.g., "parenthood perceptions"), whereas others were mentioned by women (e.g., "PA knowledge") or men (e.g., "time opportunities") only. CONCLUSIONS: Focus should be given to interventions aimed at improving parents' self-regulation skills and support on how to cope with interpersonal and situational constraints as well as parenthood perceptions.

Relative Importance of Determinants of Changes in Eating Behavior during the Transition to Parenthood: Priorities for Future Research and Interventions.

BACKGROUND: Healthy eating behavior throughout pregnancy and postpartum is important. This study aimed to investigate the perceived sex-specific importance of determinants of changes in eating behavior during pregnancy and postpartum. METHODS: Fifty-four determinants were rated by first-time parents (n = 179) on their impact. Experts (n = 31) rated the determinants in terms of their modifiability, relationship strength, and population-level effect from which a "priority for research"-score was calculated. RESULTS: During pregnancy, the three highest rated determinants by women were "health concerns", "physiological changes", and "fatigue". Men perceived "health concerns", "health consciousness", and "influence of the pregnant partner" as important. Postpartum, the three highest rated determinants by women were "adaptation to rhythm of baby", "baby becomes priority", and "practical constraints because of the baby". Men perceived "adaptation to rhythm of baby", "fatigue". and "(lack of) anticipation" as important. According to the experts, "professional influence", "food knowledge", and "home food availability" received high priority scores for both sexes and during both periods. CONCLUSIONS: Priority for research and interventions should go towards tailored family-based approaches focusing on food education in a broad sense taking into account aspects such as health consciousness, self-efficacy skills, and the social and home food environment while being supported by healthcare professionals.

Determinants of changes in women's and men's eating behavior across the transition to parenthood: a focus group study.

BACKGROUND: During the pregnancy and postpartum period, both women and men experience physiological and psychological changes, which may negatively impact their eating behavior. A clear understanding of determinants of changes in eating behavior during this period is needed to facilitate the development of targeted family-based interventions countering unfavorable dietary changes during this critical life period. METHODS: Thirteen focus group discussions targeting determinants of changes in eating behavior during pregnancy and postpartum were conducted, involving a total of 74 expecting and first-time parents. A semi-structured question guide was used to facilitate the discussions. An inductive thematic approach was used to derive main and sub-categories of determinants from the data. The Determinants of Nutrition and Eating (DONE)-framework was employed to systematically organize and label the categories and determinants. RESULTS: Two frameworks were developed; one for the pregnancy and one for the postpartum period, comprising determinants of changes in eating behavior in both women and men. Three main levels of determinants were identified: (1) the individual level, including psychological (e.g., 'health consciousness'), situational (e.g., 'effort and convenience') and biological (e.g., 'discomfort'); (2) the interpersonal level (e.g., 'social influence') and (3) the environmental level, including micro- and meso/macro (e.g., 'home/environment food availability'). Determinants acting as barriers (e.g., 'time constraints') or facilitators (e.g., 'being a role model') were identified. Many determinants were mentioned during both (e.g., 'food knowledge') or just one investigated period (e.g., 'physiological changes' during pregnancy, 'influence of the baby' postpartum). Finally, some were described by both parents (e.g., 'self-regulation'), whereas others were mentioned by women (e.g., '(perceived) food safety') or men (e.g., 'other priorities') only. CONCLUSION: The developed frameworks set the foundation for the development of future family-based interventions and may be used already by healthcare providers to provide dietary guidance and support for women and men transitioning into parenthood. A focus on the interplay of individual factors at the biological and psychological level together with situational difficulties during pregnancy is recommended. Postpartum, focus should go to support first-time parents to obtain balance of both maintaining one's own health and taking care of the baby, on improving self-regulation skills, and on coping with related situational constraints.

Misreporting of Physical Activity and Sedentary Behavior in Parents-to-Be: A Validation Study across Sex.

This study validated the International Physical Activity Questionnaire (IPAQ) and the Context-specific Sedentary Behavior Questionnaire (CSBQ) against accelerometry among parents-to-be. Sex-differences in potential misreporting of physical activity (PA) and sedentary behavior (SB) were also investigated. Self-reported total PA (TPA), light-intensity PA (LPA), moderate-intensity PA (MPA), vigorous-intensity PA (VPA), moderate-to-vigorous-intensity PA (MVPA), and SB of 91 parents-to-be (41 men and 50 women) were compared with Actigraph data according to sex. Furthermore, the extent of misreporting was compared between sexes. Strong correlations for TPA and weak-to-moderate correlations for LPA, MPA, VPA, MVPA, and SB were observed. Participants underestimated TPA by 1068 min/week (=17.8 h/week; -50%), LPA by 1593 min/week (=26.6 h/week; -83%), and SB by 428 min/week (=7.1 h/week; -11%) and overestimated MPA by 384 min/week (=6.4 h/week; +176%) and MVPA by 525 min/week (=8.8 h/week; +224%). Males overreported VPA more than females in absolute minutes per week (238 min/week, i.e., 4.0 h/week vs. 62 min/week, i.e., 1.0 h/week), whereas, in relative terms, the opposite (+850% vs. +1033%) was true. The IPAQ and CSBQ can be used with caution to estimate TPA and SB among parents-to-be considering a strong correlation but low agreement for TPA and a weak-to-moderate correlation but acceptable agreement for SB. We disadvise using these self-reports to estimate PA on the distinct intensity levels.

Comparing Calculated Nutrient Intakes Using Different Food Composition Databases: Results from the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort.

This study aimed to compare calculated nutrient intakes from two different food composition databases using data from the European prospective investigation into cancer and nutrition (EPIC) cohort. Dietary intake data of the EPIC cohort was recently matched to 150 food components from the U.S. nutrient database (USNDB). Twenty-eight of these nutrients were already included in the EPIC nutrient database (ENDB-based upon country specific food composition tables), and used for comparison. Paired sample t-tests, Pearson's correlations (r), weighted kappa's (κ) and Bland-Altman plots were used to compare the dietary intake of 28 nutrients estimated by the USNDB and the ENDB for 476,768 participants. Small but significant differences were shown between the USNDB and the ENDB for energy and macronutrient intakes. Moderate to very strong correlations (r = 0.60-1.00) were found for all macro- and micronutrients. A strong agreement (κ > 0.80) was found for energy, water, total fat, carbohydrates, sugar, alcohol, potassium and vitamin C, whereas a weak agreement (κ < 0.60) was found for starch, vitamin D and vitamin E. Dietary intakes estimated via the USNDB compare adequately with those obtained via the ENDB for most macro- and micronutrients, although the agreement was weak for starch, vitamin D and vitamin E. The USNDB will allow exposure assessments for 150 nutrients to investigate associations with disease outcomes within the EPIC cohort.

Methodological approaches to compile and validate a food composition database for methyl-group carriers in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

A standardised methodology was used to compile and validate a methyl-group carrier database (MGDB) including folate, choline, betaine and methionine, for use in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Compilation was performed by following structured guidelines to match the EPIC dietary intake data to food items from four food composition databases, according to their assigned priority of use. To assess relative validity, calculated dietary folate intakes were compared between the MGDB and the EPIC nutrient database (ENDB), used as the reference database. Folate intakes based on the MGDB and those generated using the ENDB showed good agreement (weighted κ = 0.63) and were strongly correlated (r = 0.81). This MGDB can be used for investigating potential associations between methyl-group carrier intakes and risk or prognosis of cancer and other diseases in the EPIC study population.

The effect of nudges aligned with the renewed Flemish Food Triangle on the purchase of fresh fruits: An on-campus restaurant experiment.

OBJECTIVE: This study examined the effect of nudges, inspired by the recently renewed Flemish Food Triangle, on fruit sales in a Belgian on-campus university restaurant. METHODS: In this mixed-method real-life experiment, nudges were added weekly over a period of four consecutive weeks: placement of (1) Food Triangle posters in the restaurant, (2) 'green heart' icons above the fruit stands, and (3) substitution and (4) social norm messages at the fruit stands. During baseline (no intervention) and all intervention weeks, dessert sales were registered. Short interviews were used to ask customers about their perceptions regarding the intervention. Follow-up measurements (7 and 30 weeks later) evaluated the longer-term effectiveness, while all nudges remained in place. Dessert sales were analyzed separately for both sexes, students and staff categories (based on academic degree). RESULTS: Compared to baseline, the combination of the Food Triangle and the green heart intervention materials in week 2 resulted in significant increases in fruit consumption across almost all subgroups. The other intervention materials used in the current study had rather limited effects in the short term. After 7 weeks of follow-up, significant fruit sale increases were established for all subgroups compared to baseline. At 30 weeks follow-up, the effect for staff B (Bachelor's degree) disappeared. The majority of the respondents (66.4%) had noticed at least one of the nudges, while only 3.4% indicated to have adjusted their dessert choice as a result of the nudges. CONCLUSIONS: The combination of nudges was effective in the long term and increased fruit purchase in nearly all subgroups. Short interviews show that a more active approach may be needed to increase effect sizes.

A 10-year longitudinal study on the associations between changes in plant-based diet indices, anthropometric parameters and blood lipids in a Flemish adult population.

AIM: Plant-based diets are recommended in the context of environmental sustainability and health. Since not all plant foods can be considered beneficial, a distinction needs to be made between healthful and unhealthful plant foods. The aim of this study was to investigate longitudinal associations between changes in an overall plant-based diet index, a healthful plant-based diet index and an unhealthful plant-based diet index, with changes in anthropometrics and blood lipids as indicators of morphological and metabolic fitness, respectively. METHODS: A 3-day dietary record was completed by 650 Flemish adults (420 men, 230 women) in 2002-2004 and 2012-2014. Three plant-based diet indices were calculated based on quintile scores regarding the intake of animal- or plant-based food items. Associations between 10-year changes in diet indices and changes in anthropometrics and blood lipids were tested using multivariate linear regression. RESULTS: Plant-based diet indices did not differ over time. Using the unadjusted model, few significant associations were found between changes in diet indices and changes in anthropometrics and blood lipids. However, these relationships disappeared after adjusting for confounding. In women, a positive association was found between changes in overall plant-based diet index and changes in body mass index in the adjusted model. CONCLUSIONS: Index values did not differ over time and few longitudinal associations were found.

Stability of potential renal acid load.

AIM: The potential renal acid load (PRAL) has been described in relation to different health outcomes. Outcomes over time and conclusions made are often based on baseline dietary intake values. However, to study reliable long-term associations, parameters calculated based on dietary intake data, such as PRAL, must be stable over time. Therefore, the aim of the present study was to assess the stability of PRAL and its components over a 10-year time period. METHODS: PRAL values of three-day dietary intake data from 197 women and 373 men on two assessment moments (2002-2004 and 2012-2014) were calculated. Pearson correlation and intra-class correlation coefficients were used for assessing the stability of PRAL and its components. Level of agreement between the two assessment moments was estimated after splitting up subjects in quintiles of PRAL, calculating kappa values and changes of quintiles over time. RESULTS: No significant differences in mean PRAL over time were found. Stability of PRAL and its components was low. Poor agreement between the first and second assessment was shown by low kappa values and change of most of the subjects to an adjacent and non-adjacent quintile after 10 years. CONCLUSIONS: Based on nutrition assessments carried out using three-day dietary records, stability of PRAL over a 10-year time period could not be confirmed, even though no significant difference between mean PRAL and its components over time was found. Therefore, interpretation of longitudinal outcomes based on PRAL and its component calculated at baseline should be interpreted with caution.

Body weight, body composition and energy balance related behaviour during the transition to parenthood: study protocol of a multi-centre observational follow-up study (TRANSPARENTS).

BACKGROUND: The transition to parenthood is a cornerstone event for both parents, potentially leading to relevant changes in lifestyle and behaviour. In women, the metabolic changes during and after pregnancy and the deleterious effects of excessive gestational weight gain and postpartum weight retention have been extensively described. However, there is no full understanding about which specific energy balance related behaviours (EBRB) contribute to unfavourable weight gain and weight retention. Furthermore, information on how transition to parenthood affects men is lacking. Therefore, this study aims to investigate changes in body weight, body composition and EBRB in couples transitioning to parenthood. METHODS: TRANSPARENTS is a multi-centre observational follow-up study that focuses on body weight, body composition and EBRB during the transition to parenthood. Couples (women and men) will be recruited during the first trimester of their first pregnancy. Study visits will occur at four occasions (12 weeks of pregnancy, 6 weeks postpartum, 6 months postpartum and 12 months postpartum). Anthropometrics of the parents and new-borns will be assessed including body weight, height/length, body composition (using bio-electrical impedance analysis and measurement of four skinfold thicknesses (biceps, triceps, subscapular and supraspinal/suprailiac)) and waist and hip circumference. Dietary intake, physical activity, sedentary behaviour, smoking habits, sleeping pattern, fatigue, diet and exercise related partner support, mental health, breastfeeding, contraception use, and socio-demographics will be assessed using a questionnaire. In addition, accelerometry will be used to assess physical activity and sedentary behaviour objectively. Also data from women's medical record, such as pre-pregnancy weight and pregnancy outcomes, will be included. Multilevel modelling will be used to evaluate maternal and paternal changes in body weight, body composition and EBRB during and after pregnancy (primary outcomes). Multiple linear regression analyses will be performed to identify predictors of changes in body weight, body composition and EBRB. All analyses will be adjusted for possible confounders. DISCUSSION: TRANSPARENTS is a unique project identifying vulnerable parents and (un)favourable changes in EBRB throughout this potentially critical life period. Provided insights will facilitate the development of effective intervention strategies to help couples towards a healthy transition to parenthood. TRIAL REGISTRATION: Clinicaltrials.gov Identifier: NCT03454958. Registered March 2018.

The effect of a portion size intervention on French fries consumption, plate waste, satiety and compensatory caloric intake: an on-campus restaurant experiment.

BACKGROUND: One of the driving factors of dietary overconsumption throughout the last decennia is the increase of food portion sizes. Larger portions induce higher daily energy intake, so reducing portion size may reduce intake of excess calories. However, real-life studies about the effects of portion size reduction are lacking. Therefore, this study examined the effect of a French fries portion size reduction on French fries consumption, French fries plate waste, satiety and caloric intake during the subsequent afternoon among university students and employees in a Belgian on-campus restaurant setting. Moreover, this study evaluated consumers' perception about the portion size reduction. METHODS: The study took place over a two-time (i.e. baseline and intervention week) 4-day period (Tuesday-Friday) in the on-campus restaurant where ±1200 meals are served every day. French fries' portions were reduced by 20% by replacing the usual porcelain bowl served during the baseline week (±200 g) with smaller volume paper bags during the intervention week (±159 g) in a pre-post real-life experiment. French fries consumption and plate waste were measured in 2056 consumers at baseline and 2175 consumers at intervention. Additionally, interviews were conducted directly after lunch and again between 4 and 6 p.m. on the same day to assess satiety and caloric intake at pre and post in a small subsample of both French fries consumers (n = 19) and non-French fries consumers (n = 14). Post-intervention, the same subsample was interviewed about their perception of the portion size reduction (n = 28). RESULTS: Total French fries intake decreased by 9.1%, and total plate waste decreased by 66.4%. No differences were found in satiety or caloric intake between baseline and intervention week among the French fries' consumers. The majority (n = 24, 86%) of French fries consumers noticed the reduction in portion size during the intervention. Although most participants (n = 19, 68%) perceived the reduced portion size as sufficient, only a minority of participants (n = 9, 32%) indicated post-intervention that they would agree with a permanent implementation. CONCLUSIONS: Reducing portion size may lead to reduced caloric intake, without changing perceived levels of satiety.