On March 15, 2020, the Dutch Government implemented COVID-19 lockdown measures. Although self-quarantine and social-distancing measures were implemented, restrictions were less severe compared to several other countries. The aim of this study was to assess changes in eating behavior and food purchases among a representative adult sample in the Netherlands (n = 1030), five weeks into lockdown. The results show that most participants did not change their eating behaviors (83.0%) or food purchases (73.3%). However, socio-demographic differences were observed among those that reported changes during lockdown. For example, participants with overweight (OR = 2.26, 95%CI = 1.24–4.11) and obesity (OR = 4.21, 95%CI = 2.13–8.32) were more likely to indicate to eat unhealthier during lockdown compared to participants with a healthy weight. Those with a high educational level (OR = 2.25, 95%-CI = 1.03–4.93) were also more likely to indicate to eat unhealthier during lockdown compared to those with a low educational level. Older participants were more likely to indicate to experience no differences in their eating behaviors compared to those of younger age, who were more likely to indicate that they ate healthier (OR = 1.03, 95%CI = 1.01–1.04) as well as unhealthier (OR = 1.04, 95%CI = 1.02–1.06) during lockdown. Participants with obesity were more likely to indicate to purchase more chips/snacks (OR = 2.79, 95%CI = 1.43–5.45) and more nonalcoholic beverages (OR = 2.74, 95%CI = 1.36–5.50) during lockdown in comparison with those with a healthy weight. Of those that used meal delivery services before, 174 (29.5%) indicated to use meal delivery services more frequently during lockdown. Although the results confirm the persistence of dietary routines, profound socio-demographic differences were observed for those that did report changes. Especially for individuals with overweight and obesity, the lockdown has taken its toll on healthy dietary choices. Further research should unravel underlying mechanisms for these observations.

BackgroundFood literacy refers to the capability to make healthy food choices in different contexts, settings and situations. The aim of this study is to develop and validate the self-perceived food literacy (SPFL) scale, to assess individuals’ level of food literacy, including a knowledge, skills and behavior to plan, manage, select, prepare and eat food healthfully.MethodsAn initial set of 50 items for the SPFL scale were generated based on expert insights and literature. A cross-sectional online survey was conducted among a sample of Dutch adults (n = 755) in order to determine convergent, divergent and criterion validation against psychosocial variables that were expected to correlate with food literacy (self-control, impulsiveness) and against the expected outcome of high food literacy, namely healthy food consumption. Principal Component Analyses (PCA), Pearson correlation tests and linear regression analyses were conducted. The capacity to distinguish of the SPFL scale was determined by comparing SPFL scores of the general population with that of a sample of dieticians (n = 207).ResultsThe participants in the general sample had an average age of 44.8 (SD:16.1), the majority were women (90.7%), they had a healthy weight (61.4%) and were highly educated (59.1%). Of the initial 50 items, 29 items remained after PCA and reflected eight domains of food literacy. SPFL was positively correlated with self-control (r = 0.51, p = <.001) and negatively with impulsiveness (r = − 0.31, p = <.01). Participants with higher levels of food literacy reported a significantly higher frequency of fruit consumption (≥5 times/week), vegetable consumption (≥5times/week) and fish consumption (≥1times/week) and consumed larger portions of fruit (≥2pieces/day) and vegetables ≥200 g/day) in comparison with participants who had lower levels of food literacy. Dieticians had slightly higher scores on SPFL than general adults (B = 0.08, SE = 0.03, t = 2.83, 95%-CI = 0.03 to 0.14).ConclusionsThe 29 item SPFL scale is a validated, expert-based and theory-driven tool for measuring self-perceived food literacy with respect to healthy eating among adults. Higher levels of food literacy were associated with more self-control, less impulsiveness and healthier food consumption. Additional research is needed to validate the SPFL scale in different populations (different age groups, socioeconomic groups, male populations) and in different contexts.Electronic supplementary materialThe online version of this article (10.1186/s12966-018-0687-z) contains supplementary material, which is available to authorized users.

Purpose of ReviewThe aim of this review is to provide an overview of (1) underlying mechanisms of the effect of portion size on energy intake, (2) external factors explaining the portion size effect and (3) interventions and measurements aimed at food portion size.Recent FindingsPrevious studies have shown that portion sizes have increased in recent decades. Many experimental studies have been conducted to unravel the mechanisms underlying the portion-size effect on food intake (e.g. the appropriateness mechanism, the ‘unit bias’ mechanism, the ‘previous experience/expectation’ mechanism, the ‘visual cue’ mechanism and the ‘bite size’ mechanism). In addition, external factors have been found to drive food portion selection and consumption (e.g. value for money, mindless eating, levels of awareness, estimation bias. Research on several interventions (ranging from ‘providing information’ to ‘eliminating choice’) have been conducted, but remain scarce, especially intervention studies in which portion size is a key focus in weight loss. Moreover, only three new instruments with respect to portion control behavior have been developed.SummaryThere is considerable evidence for the portion-size effect on energy intake. However, the work on interventions targeting portion size and measurements for portion control behavior are limited. Moreover, from the literature it is not yet clear what type of interventions work best, for whom and in what context.

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Advances in commercial wearable devices are increasingly facilitating the collection and analysis of everyday physiological data. This paper discusses the theoretical and practical aspects of using such ambulatory devices for the detection of episodic changes in physiological signals as a marker for mental state in outdoor environments. A pilot study was conducted to evaluate the feasibility of utilizing commercial wearables in combination with location tracking technologies. The study measured physiological signals for 15 participants, including heart rate, heart-rate variability, and skin conductance. Participants' signals were recorded during an outdoor walk that was tracked using a GPS logger. The walk was designed to pass through various types of environments including green, blue, and urban spaces as well as a more stressful road crossing. The data that was obtained was used to demonstrate how biosensors information can be contextualized and enriched using location information. Significant episodic changes in physiological signals under real-world conditions were detectable in the stressful road crossing, but not in the other types of environments. The article concludes that despite challenges and limitations of current off-the-shelf wearables, the utilization of these devices offers novel opportunities for evaluating episodic changes in physiological signals as a marker for mental state during everyday activities including in outdoor environments.