Integration of an Image-Based Dietary Assessment Paradigm into Dietetic Training Improves Food Portion Estimates by Future Dietitians

The use of image-based dietary assessments (IBDAs) has rapidly increased; however, there is no formalized training program to enhance the digital viewing skills of dieticians. An IBDA was integrated into a nutritional practicum course in the School of Nutrition and Health Sciences, Taipei Medical University Taiwan. An online IBDA platform was created as an off-campus remedial teaching tool to reinforce the conceptualization of food portion sizes. Dietetic students’ receptiveness and response to the IBDA, and their performance in food identification and quantification, were compared between the IBDA and real food visual estimations (RFVEs). No differences were found between the IBDA and RFVE in terms of food identification (67% vs. 71%) or quantification (±10% of estimated calories: 23% vs. 24%). A Spearman correlation analysis showed a moderate to high correlation for calorie estimates between the IBDA and RFVE (r ≥ 0.33~0.75, all p < 0.0001). Repeated IBDA training significantly improved students’ image-viewing skills [food identification: first semester: 67%; pretest: 77%; second semester: 84%) and quantification [±10%: first semester: 23%; pretest: 28%; second semester: 32%; and ±20%: first semester: 38%; pretest: 48%; second semester: 59%] and reduced absolute estimated errors from 27% (first semester) to 16% (second semester). Training also greatly improved the identification of omitted foods (e.g., condiments, sugar, cooking oil, and batter coatings) and the accuracy of food portion size estimates. The integration of an IBDA into dietetic courses has the potential to help students develop knowledge and skills related to “e-dietetics”.

How You Estimate Calories Matters: Calorie Estimation Reversals

Consumers often form calorie estimates. How consumers estimate calories can systematically bias their calorie assessments. We distinguish between magnitude estimates—when consumers judge whether something has “very few” to “many” calories—and numeric estimates—when consumers estimate a number of calories. These two estimation modes lead to calorie estimate reversals when assessing calories in stimuli that trade off type and quantity, such as when assessing calories in a smaller portion of unhealthy food versus a larger portion of healthier food. When forming a “magnitude estimate,” people judge the larger, healthier food portion as containing fewer calories than the smaller, unhealthy food portion. However, when forming a “numeric estimate,” people often come to the opposite conclusion—judging the larger, healthier food portion as having more calories. This reversal occurs because these two estimation modes are differentially sensitive to information regarding a stimulus’ type (e.g., food healthiness), which is processed first, and quantity (e.g., food portion size), which is processed secondarily. Specifically, magnitude estimates are more sensitive to type, whereas numeric estimates attend to both type and quantity. Accordingly, this divergence between calorie estimation modes attenuates when: 1) quantity information is made primary or 2) in an intuitive (vs. deliberative) mindset.

Larger portions make me eat more: Awareness of the external factors that influence food intake

There is consistent evidence that the amount of food people consume can be influenced by external factors, such as food portion size or the amount of food others are eating. However research studies to date have suggested that people are generally unaware of the influence that these external factors have on food intake. In the present research we directly tested whether consumers are aware of how external factors can affect their food intake. In Study 1 we re-analysed data from a study in which an effect of portion size on food intake was observed and post-consumption, participants were asked whether they believed portion size had influenced their food intake. In Study 2 participants were asked to indicate whether several different external factors known to increase food intake would be likely to increase, decrease or have no effect on how much they would eat in hypothetical scenarios. In Study 1, a large proportion of participants (56%) believed that their food intake was influenced by portion size. In Study 2, a large proportion of participants accurately identified that external factors known to affect eating behaviour would be likely to increase their food intake: portion size (73%), social influence (40%), food variety (75%), and distraction (59%). Together these results suggest that consumers show awareness of the influence that external factors have on their food intake.

Portion size and energy contribution of food in adolescents from São Paulo, Brazil: Changes between 2003 and 2015

Introduction: Overweight has become a very important issue in the epidemiological scenario of nutrition due to its increasing rates and association with several chronic noncommunicable diseases. The etiology of overweight is complex, but diet is one of the modifiable factors that may interfere in the nutritional status of individuals and consequently on overweight and obesity. One aspect of the diet that has been related to overweight is the increase of energy intake, and related to that, the increase on food portion size.Objective: To evaluate differences in food portions size and its energy contribution in adolescents from São Paulo, Brazil between 2003, 2008 and 2015.Materials and Methods: Cross-sectional population-based study with a representative sample of 1711 adolescents aged 12 to 19 years who participated in the Health Survey of São Paulo (HS-SP). The HS-SP was conducted in 2003, 2008 and 2015. Overweight was defined according to the cutoff points of the World Health Organization (WHO) for adolescents (BMI ≥ p85). Dietary data were obtained from two 24-hour recalls.Reported foods were classified into groups and the prevalence of consumers, the percentage of energy contribution, and the mean and median of portion sizes in each food group were calculated.Results: Over the years, the prevalence of overweight in adolescents increased from 13.8% to 29.4%. The prevalence of consumers of salty snacks, fruits, industrialized juices, red meats, rice, sweets/desserts and toast/cookies has increased; while the number of consumers of coffee/tea, fruit juice, milk, artisan/non-packaged snacks and sugar decreased. The food groups with the highest energy contribution were: rice (14%), red meat (12%) and bread (9%) in all the years evaluated. The groups with the greatest increase in the energy contribution from 2003 to 2015 were: toast / cookies, sweets / desserts, white and red meats, and industrialized juices. The consumption portion size of eggs has increased, while those of cold cuts, fruits, industrialized juices, rice and tubers/roots decreased.Discussion: There was a diverse variation in the frequency of intake, the energy contribution and the food portion size over time with increase in some groups and decrease in others. These findings provide useful data to support future interventions and public policies focused on adolescent feeding.

Portion size normality and additional within-meal food intake: two crossover laboratory experiments

Reducing food portion size could reduce energy intake. However, it is unclear at what point consumers respond to reductions by increasing intake of other foods. We predicted that a change in served portion size would only result in significant additional eating within the same meal if the resulting portion size was no longer visually perceived as ‘normal’. Participants in two crossover experiments (Study 1: n 45; Study 2: n 37; adults, 51 % female) were served different-sized lunchtime portions on three occasions that were perceived by a previous sample of participants as ‘large-normal’, ‘small-normal’ and ‘smaller than normal’, respectively. Participants were able to serve themselves additional helpings of the same food (Study 1) or dessert items (Study 2). In Study 1 there was a small but significant increase in additional intake when participants were served the ‘smaller than normal’ compared with the ‘small-normal’ portion (m difference = 161 kJ, P = 0·002, d = 0·35), but there was no significant difference between the ‘small-normal’ and ‘large-normal’ conditions (m difference = 88 kJ, P = 0·08, d = 0·24). A similar pattern was observed in Study 2 (m difference = 149 kJ, P = 0·06, d = 0·18; m difference = 83 kJ, P = 0·26, d = 0·10). However, smaller portion sizes were each associated with a significant reduction in total meal intake. The findings provide preliminary evidence that reductions that result in portions appearing ‘normal’ in size may limit additional eating, but confirmatory research is needed.

Analysis of the National Adult Nutrition Survey (Ireland) and the Food4Me Nutrition Survey Databases to Explore the Development of Food Labelling Portion Sizes for the European Union

The present study set out to explore the option of developing food portion size for nutritional labelling purposes using two European Union (EU) dietary surveys. The surveys were selected as they differed in (a) methodologies (food diary versus food frequency questionnaire), (b) populations (Irish National Adult Nutrition Survey (NANS) versus a seven-country survey based on the pan EU study Food4Me), (c) food quantification (multiple options versus solely photographic album) and (d) duration (4 consecutive days versus recent month). Using data from these studies, portion size was determined for 15 test foods, where portion size was defined as the median intake of a target food when consumed. The median values of the portion sizes derived from both the NANS and Food4Me surveys were correlated (r = 0.823; p < 0.00) and the mean of the two survey data sets were compared to US values from the Recognized as Customarily Consumed (RACC) database. There was very strong agreement across all food categories between the averaged EU and the US portion size (r = 0.947; p < 0.00). It is concluded that notwithstanding the variety of approaches used for dietary survey data in the EU, the present data supports using a standardized approach to food portion size quantification for food labelling in the EU.