Reducing meat consumption is encouraged to improve diet environmental sustainability. It results in reducing protein intake, and this can have consequences on eating behaviour. To better characterise these consequences, six-week-old male Wistar rats were divided into 5 groups receiving diets differing by their protein source and amount. Two groups received a casein (C) diet, containing 20% (C20) or 6% (C6) protein, a casein density known to induce a hyperphagic response in rats. Three groups received a dehydrated bovine protein (DBP) diet, containing 6% (B6), 10% (B10), or 20% (B20) protein. C20 and B20 rats had also free access to 40% protein pellets (casein for C20 and DBP for B20), but choose to maintain their protein intake close to 20%. C20 and B20 rats showed similar growth and food consumption throughout the 12-week experiment. B6 rats showed reduced growth (-26%) and lean body mass despite similar food consumption to B20. C6 and B10 rats increased their food intake (C6 by +20% relative to C20; B10 by +30% relative to B20) and showed similar growth to C20 and B20 rats. Comparison of amino acid intakes suggests that the amplitude of food overconsumption allowed C6 and B10 rats to achieve a threshold intake of specific essential amino acids. C6 and B10 rats had more visceral adiposity than C20 and B20 rats, but similar lean body mass. Our results characterize the hyperphagic response to moderate meat protein reduction, showing that it increases adiposity, then providing some insights into the obesogenic risk potentially associated with reduced meat consumption.

This study aims to uncover the diverse factors that influence meal composition decisions in university restaurant settings. To achieve this, we employed a combination of agent-based modeling and in-situ measurements of meal choices made by guests in natural consumption situations. Our model considered individual preferences for presented dishes, social influence from other agents in the simulated environment, and environmental factors such as sensory perceptions and waiting time. Simultaneously, we conducted observations in two university restaurants during lunchtime, recording the meal choices of 336 students. Anthropometric data and subjective decision criteria were collected through self-reported questionnaires, and the composition of each guest's table was recorded as a proxy for familiarity between individuals. By utilizing the measured characteristics of the participants as initial parameters, we simulated choices and compared them with real participant data, allowing us to determine the importance of preferences, social influences, and environmental factors in decision-making. Despite the majority of respondents claiming no influence from others, our best fit models indicated a significant role for social influence in agents' decisions. Moreover, our model exploration revealed that not all dishes are equally susceptible to social influences, with variations in this parameter affecting different meal components differently. This study demonstrates how a multi-agent simulation approach can effectively characterize the influencing factors involved in complex decision-making problems and uncover mechanisms during meal composition in natural consumption situations.

Balancing our dietary intakes in favour of plant protein sources would reduce overall protein intake. Low-protein diets have shown to reinforce specific appetite for protein. The role of protein appetite as a determinant of the choice of specific protein sources in free-living humans has not been extensively studied, and the relationship between the strength of protein appetite and the amount of protein from various dietary sources has not yet been quantified. We used an on-line questionnaire to measure the association between habitual intakes of principal protein sources and protein valuation in a cohort of healthy French meat-eating adults, aged between 18 and 65 years. Protein valuation is the propensity to systematically prefer foods that are higher in protein and is measured using a 2-alternative forced-choice task. Participants (final sample: N = 86) who had higher habitual intakes of protein displayed a significantly higher protein valuation. There was a significant positive association between protein valuation and intakes of various food groups of animal origin, especially meat, while this association between protein valuation and intake of plant-based foods was negative and significant. Our study suggests that protein valuation may be a determinant of preferences for protein and specific protein sources. Nutritional determinants of protein preferences should be taken into account in the context of a population-wide shift to more plant-based diets in order to facilitate this shift for all.

Regulation of meat consumption appears to be a relevant public policy to limit diet-related greenhouse gas emissions. However, the real impact of such a policy (e.g., tax) on human health and nutrition remains uncertain, especially for underprivileged individuals. Based on representative data from France, we estimate potential trend differences in the association between meat consumption and nutritional outcomes, such as body mass index (BMI) and unhealthy food intake, according to individual educational attainment. We reveal that among adults with low education levels, reduced meat consumption was significantly associated with a higher BMI, a higher risk of being overweight, and greater intake of ultra-processed foods, sweet drinks, and sugar. By contrast, reduced meat consumption was associated with healthier nutritional status for the most educated individuals. These results are robust to several measurements of socioeconomic status (SES) such as household income, occupation, and financial insecurity perception. In summary, high-SES individuals may be more prone to replace meat with healthy alternatives, whereas low-SES individuals may tend to replace meat with energy-dense foods and beverages, including ultra-processed foods. In terms of the contribution to science and society, this study is the first to show that SES changes the relationship between meat consumption and nutritional outcomes. Our findings call for future research on this topic to provide actionable recommendations to implement a fair and healthy food transition.

PURPOSE:The present study aimed to explore the implicit associations between food and bodily stimuli in patients with anorexia nervosa (AN) and control subjects (HC). METHODS:A Go/No-Go Association Task was administrated to 55 participants (28 AN and 27 HC), using food stimuli (low-calorie food vs. high-calorie food) and body stimuli (underweight vs. overweight bodies). RESULTS:We evidenced an implicit association between food and body stimuli in the AN group, whereas the HC group only showed a tendency. AN and HC groups also exhibited different categorization strategies: the AN group tended to categorize stimuli as low-calorie foods and underweight bodies less than the HC group, and they tended to categorize stimuli as high-calorie foods and overweight bodies more than the HC group. CONCLUSION:The present study revealed for the first time specificities of the AN population's implicit association between food and body stimuli in terms of association strength and categorization strategy. Furthermore, the results suggest that combining implicit methodologies with other methods could contribute to a better characterization of the physiopathology of AN. LEVEL OF EVIDENCE:Level I, experimental study.

Social norms could be a tool in dietary transition toward more sustainable diets, but the results of social norms interventions aimed at encouraging the selection of plant-based foods to date have been inconsistent. One reason for this might be because there are important moderating factors that have yet to be investigated. Here we examine social modeling of vegetarian food choices and test whether modeling is dependent upon individual intentions to follow a vegetarian diet in the future in two different settings. In a laboratory study of 37 women, participants with low intentions to become a vegetarian consumed fewer plant-based foods in the presence of a vegetarian confederate, compared to eating alone. In an observational study of 1,037 patrons of a workplace restaurant, participants with a higher score of on vegetarian intentions had a greater likelihood of taking a vegetarian main course or starter, and a vegetarian social norm was associated with a greater likelihood of a vegetarian choice for the main course but not for the starter. These data suggest that participants with low intentions to follow a vegetarian diet may exhibit reactance against an explicit vegetarian norm in an unfamiliar context (as in Study 1) but that general norm following regardless of dietary intentions be more likely when it is conveyed implicitly in a familiar context (as in Study 2).

BACKGROUND:Along with the popularity of smartphones, artificial intelligence-based personalized suggestions can be seen as promising ways to change eating habits toward more desirable diets. OBJECTIVES:Two issues raised by such technologies were addressed in this study. The first hypothesis tested is a recommender system based on automatically learning simple association rules between dishes of the same meal that would make it possible to identify plausible substitutions for the consumer. The second hypothesis tested is that for an identical set of dietary-swaps suggestions, the more the user is-or thinks to be-involved in the process of identifying the suggestion, the higher is their probability of accepting the suggestion. METHODS:Three studies are presented in this article, first, we present the principles of an algorithm to mine plausible substitutions from a large food consumption database. Second, we evaluate the plausibility of these automatically mined suggestions through the results of online tests conducted for a group of 255 adult participants. Afterward, we investigated the persuasiveness of 3 suggestion methods of such recommendations in a population of 27 healthy adult volunteers through a custom designed smartphone application. RESULTS:The results firstly indicated that a method based on automatic learning of substitution rules between foods performed relatively well identifying plausible swaps suggestions. Regarding the form that should be used to suggest, we found that when users are involved in selecting the most appropriate recommendation for them, the resulting suggestions were more accepted (OR = 3.168; P < 0.0004). CONCLUSIONS:This work indicates that food recommendation algorithms can gain efficiency by taking into account the consumption context and user engagement in the recommendation process. Further research is warranted to identify nutritionally relevant suggestions.

Food odour is a potent stimulus of food intake. Odour coding in the brain occurs in synergy or competition with other sensory information and internal signals. For eliciting feeding behaviour, food odour coding has to gain signification through enrichment with additional labelling in the brain. Since the ventral striatum, at the crossroads of olfactory and reward pathways, receives a rich dopaminergic innervation, we hypothesized that dopamine plays a role in food odour information processing in the ventral striatum. Using single neurones recordings in anesthetised rats, we show that some ventral striatum neurones respond to food odour. This neuronal network displays a variety of responses (excitation, inhibition, rhythmic activity in phase with respiration). The localization of recorded neurones in a 3-dimensional brain model suggests the spatial segregation of this food-odour responsive population. Using local field potentials recordings, we found that the neural population response to food odour was characterized by an increase of power in the beta-band frequency. This response was modulated by dopamine, as evidenced by its depression following administration of the dopaminergic D1 and D2 antagonists SCH23390 and raclopride. Our results suggest that dopamine improves food odour processing in the ventral striatum.

Nutritional information via simplified labelling on products’ front of pack has become common in retail stores and is now concerning nowcollective catering. While numerous studies have investigated the effects of such information policies on consumers' decisions in shops, few studies have focused on choices made in collective catering. In such settings, consumers must compose a meal by combining dishes to be eaten during the same occasion. Each choice is then dependent of the selection of other foods, yielding a different decision problem as in a store where items are selected independently of one another. The aim of this study was to understand whether a nutritional labelling, (Nutri-Score®), modified the choices of consumers and more precisely modified the meal composition strategies - the associations between dishes made by consumers. A computerized menu composition task was designed, 371 participants were randomly redirected either to an interface displaying the Nutri-Score® of dishes, or to an interface showing the dishes without Nutri-Score®. Bayesian logistic regressions were used to explore dependency relationships between foods in presence or absence of Nutri-Score®. When considering dishes individually, no significant effects of the Nutri-Score® were observed, but significant effects of the Nutri-Score® on composition strategies could be observed. Two types of strategies seemed to emerge: homogeneous behaviors, where selected dishes had similar scores and, compensatory behaviors where selected dishes had contrasted scores. In conclusion, the effect of a nutritional labelling can have complex consequences on food decisions that extend beyond the selection of food items taken individually.

Changes in dietary habits of the French population have been reported during the national lockdown that was enforced due to the COVID-19 pandemic. This study investigated whether perceived social eating norms were associated with the initiation and maintenance of dietary changes that took place as a result of lockdown. An online study collected information on (1) changes in consumption implemented during the lockdown and the maintenance of these changes, and (2) perceptions about changes in consumption implemented during lockdown by household members, relatives out of home, and the general population. The changes in consumption were classified as foods to increase or to decrease according to French national recommendations. The perception of changes to dietary habits by household members and relatives out of home was related to the changes made by individuals for each of the food categories (all p < 0.05) but not to the perception of changes made the general population. Increased consumption of foods to increase was more likely to be maintained when there was a positive perception of the changes made by household members (p = 0.03). These results highlight the influence of the perception of social eating norms, especially by household members and relatives, on the implementation of dietary changes during lockdown and suggest that social eating norms can have a lasting influence.

BACKGROUND:A low-protein diet can induce compensatory intake of excess energy. This must be better evaluated to anticipate the obesogenic risk that may result from the dietary recommendations for reducing animal protein consumption.OBJECTIVES:We aimed to further characterize the behavioral and physiological responses to a reduction in dietary protein and to identify the determinants of protein appetite.METHODS:Thirty-two male Wistar rats [4 wk old, (mean ± SEM) 135 ± 32 g body weight] were fed a low-protein (LP; 6% energy value) or normal-protein (NP; 20%) diet for 8 wk. Food intake and body mass were measured during the entire intervention. During self-selection sessions after 4 wk of experimental diets, we evaluated rat food preference between LP, NP, or high-protein (HP; 55%) pellets. At the end of the experiment, we assessed their hedonic response [ultrasonic vocalizations (USVs)] and c-Fos neuronal activation in the olfactory tubercle and nucleus accumbens (NAcc) associated with an LP or HP meal.RESULTS:Rats fed an LP diet had greater food intake (24%), body weight (5%), and visceral adiposity (30%) than NP rats. All LP rats and half of the NP rats showed a nearly exclusive preference for HP pellets during self-selection sessions, whereas the other half of the NP rats showed no preference. This suggests that the appetite for proteins is driven not only by a low protein status but also by individual traits in NP rats. LP or HP meal induced similar USV emission and similar neuronal activation in the NAcc in feed-deprived LP and NP rats, showing no specific response linked to protein appetite.CONCLUSIONS:Protein appetite in rats is driven by low protein status or individual preferences in rats receiving adequate protein amounts. This must be considered and further analyzed, in the context of current recommendations for protein intake reduction.

The social context of eating has a profound effect on consumption choices. Social modeling, that involves using others? behavior as a guide for appropriate consumption, has been well documented for food intake, but less is known about social modeling of food choices. Moreover, social modeling has mainly been studied in laboratory settings. We conducted an observational study in a self-service canteen to examine whether the food choices of an individual were influenced by the choice of the person ahead in the queue. We recorded food choices of 546 individuals (333 men and 211 women) and those of the person in front of them in the queue along a linear buffet. Starters were sub-categorized into salads, mixed starters (e.g. avocado shrimp mayonnaise), and cold meat starters, and desserts were sub-categorized into fruits, dairy products and pastries. There was a significantly higher probability of taking a starter in general (OR = 1.65, IC = 1.06?2.57, p = 0.03), a salad (OR = 1.78, CI = 1.08?2.93, p = 0.02), a mixed starter (OR = 2.98, CI = 1.42?6.05, p < 0.01), but not a cold meat, if the person ahead in the queue also took one compared to when the person ahead did not take one. No significant modelling was found for desserts which may be because almost all participants took a dessert. These results highlight that social modeling influences food choices, and that this phenomenon can be observed in a real life setting. These data also suggest that some food categories, such as starters, could be more susceptible to social modeling than are others. Finally, we observed modeling both between familiar and unfamiliar participants, which suggests that social norms could be used to promote healthier eating in a range of settings including friendship groups.