As stress is hypothesised to influence dietary behaviour, the relationship between perceived stress and diet quality in European adolescents was investigated. Within the Healthy Lifestyle in Europe by Nutrition in Adolescence study, adolescents (n 704, aged 12–17 years) from schools in five European cities (Ghent, Stockholm, Zaragoza, Athens and Vienna) completed a 2 d 24 h dietary recall assessment and an Adolescent Stress Questionnaire. Measurements and information were taken on height, weight, pubertal stage, parental education level, the level of moderate-to-vigorous physical activity (MVPA) and sleep duration. The Diet Quality Index for Adolescents (DQI-A) was calculated from the dietary data, which comprised three components reflecting dietary diversity, quality and equilibrium. Hierarchical linear models were performed to investigate the relationship between the adolescents' level of perceived stress and the DQI-A and its components, adjusting for relevant covariates (age, BMI z-score, pubertal stage and parental education). These models were additionally adjusted for MVPA or sleep duration. In both boys and girls, perceived stress was a significant independent negative predictor for their overall DQI-A. This inverse relationship was observed for all dietary components, except for dietary diversity in boys, and it was unaltered when additionally adjusted for MVPA or sleep duration. The observed inverse relationship between stress and diet quality within these European adolescents supports the hypothesis that stress influences dietary behaviour, thus emphasising the need for preventive stress-coping strategies for adolescents.

Exposure to the sight and smell of food influences our momentary desire to consume it. This study explored the process by which cue exposure promotes greater consumption of food. Three hypotheses were explored, cue exposure: (i) increases the planned consumption of food; (ii) increases tolerance of larger portion sizes; (iii) arrests the development of satiety. Female participants (n 50) were each tested in two conditions. In a ‘cue condition’ they were exposed to the sight and smell of pizza for 60 s. Before and after this period they provided information about prospective and maximum tolerated portion sizes and their desire to eat pizza and other non-cued foods. Participants then consumed a fixed portion of pizza, rated their hunger and were finally offered ad libitum access to pizza. In the ‘no-cue condition’, cue exposure was replaced with a cognitive task. Cueing had little effect on tolerance of larger portion sizes or on hunger after consuming the fixed portion. Instead, it increased prospective pizza portion size and subsequent intake of pizza. Together, these results suggest that cueing increases the amount of food that people actively plan to eat. This plan is then executed, leading to greater intake. Pizza cueing also increased prospective portion size of other foods. Thus, contrary to previous reports, effects of exposure may generalise to other foods. Finally, we found evidence that restrained eaters are less ‘cue reactive’ than unrestrained eaters. In future, our approach might be adapted to consider whether heightened ‘cue reactivity’ represents a risk factor for obesity.

Cravings are hedonic responses to food, characterised by their intensity and their specificity. Food cravings are extremely common, reported by the majority of young adults. They are closely associated with liking but not synonymous with increased intake. Structured interviews and prospective incident accounts of food cravings have succeeded in revealing a richness of information about their character, their antecedents and their consequences. In addition, laboratory investigations are adding to what is being learned from field and clinical studies. Taking dieting as an example of an assumed influence on food craving, the outcomes of cross-sectional studies are mixed and unconvincing. Prospective and experimental research shows a clearer relationship. Dieting or restrained eating generally increase the likelihood of food craving while fasting makes craving, like hunger, diminish. Attempted restriction or deprivation of a particular food is associated with an increase in craving for the unavailable food. This relationship suggests a variety of underlying cognitive, conditioning and emotional processes, of which ironic cognitive processes, conditioned cue reactivity and dysphoric mood are prominent. Food cravings may also be self-attributions, accounting for why a highly-palatable but self-restricted food is (over-)consumed. Overall, the popularised account of cravings as elicited by specific nutritional need is having to give way to a more subtle and complex appreciation of human eating behaviour.

Two experiments explored the hypothesis that distraction causes a reduced sensitivity to the physiological and sensory cues that signal when to terminate a meal. In Experiment 1, eighty-eight females ate five ‘Jaffa Cakes’ either while distracted by a computer game or while sitting in silence. Analysis of the difference in rated hunger, fullness and desire to eat (pre- to post-intake) revealed that distracted participants experienced smaller changes in their desire to eat and fullness than did non-distracted participants. Experiment 2 assessed whether changes in ratings are attenuated because sensory-specific satiety (or a related process) fails to develop. Using a similar procedure, eighty-four females provided desire to eat, pleasantness and intensity ratings for Jaffa Cakes and for two ‘uneaten’ foods, both before and at three time-points after consuming five Jaffa Cakes. Non-distracted participants reported a reduction in their desire to eat the eaten food relative to the uneaten food (food-specific satiety), whereas distracted participants maintained a desire to eat all foods. Moreover, this difference between distracted and non-distracted participants was evident 5 and 10 min after the eating episode had terminated. The present findings invite speculation that distraction attenuates the development of sensory-specific satiety, and that this effect persists (at least for a brief period) after the distractor has terminated. More generally, this kind of phenomenon warrants further scrutiny because it holds the potential to contribute towards overeating, either by prolonging an eating episode or by reducing the interval between meals.

The effect of energy density (ED) on energy intake (EI) has been assessed in short-term and long-term experiments. In the short term, it was found that ED affects EI directly in situations when the subjects cannot estimate the ED of the food; then subjects mainly monitor the weight of the food ingested. In the long term, the effects of ED on EI are modulated. Average daily EI appears to be related to ED of the food and drinks when ED is determined by specific macronutrients, but not when ED is only determined by the weight of water. Thus, the short-term effect ED has on EI cannot be extrapolated to the long term, because a possible dominating effect of the weight of water determining ED undoes the relationship of ED with EI. Moreover, in the long-term portion sizes are used to compensate for correctly estimated ED, resulting in less variation in EI than ED alone would imply. Finally, dietary restraint compensates for the effect of a relatively high ED on daily EI, whereas dietary unrestraint compensates for the effect of relatively low ED on daily EI. We conclude that the short-term effect of ED on EI is modulated by the effect of water on ED, and compensated for by the effect of dietary restraint and adapted portion sizes.

The relationship between energy density (ED) of food and drink consumption ad libitum and energy intake (EI) was analysed. EI was taken as average daily EI over the long term, and as EI during a single meal. Moreover, the distribution of EI over three ED categories was analysed. Average daily EI was related to ED of the food and drinks when ED was strongly influenced by specific macronutrients. When ED was strongly influenced by the weight of water, it was not related to EI. During a meal subjects monitored mainly weight, and to a lesser extent, the energy content of the food ingested. Therefore, covertly manipulated ED of a meal affected EI directly. The impact of ED on EI was modulated by dietary behaviours such as restraint. Overt manipulation of ED for 6 months showed that EI was adjusted to a decreased but not to an increased ED in dietary-unrestrained subjects, and that EI was adjusted to an increased but not to a decreased ED in dietary-restrained subjects. Knowledge of ED was shown to lead to an inverse relationship between portion sizes and ED during a meal. Average daily EI consisted of a distribution of EI over the three different categories of ED, so that obese women ate more of foods with a high ED and less of foods with a low ED compared with normal weight women (and nutritional guidelines). In conclusion, ED affected daily EI by means of macronutrient specific effects. EI from a meal with an unknown ED can become inversely related to EI through learning or conditioning. Therefore, the effect of ED on EI during a single meal observation cannot be extrapolated directly to the 24 h effect on EI. With regard to the treatment of obesity, a conscious decreased consumption of foods high in ED and an increase in consumption of low-ED food is necessary to decrease and subsequently maintain body weight, particularly in subjects with a sedentary lifestyle.

The objective of this investigation was to compare the acute effects of exercise and diet manipulations on energy intake, between dietary restrained and unrestrained females. Comparisons of two studies using an identical 2 × 2 repeated-measures design (level of activity (rest or exercise) and lunch type (high-fat or low-fat)) including thirteen dietary unrestrained and twelve restrained females were performed. Energy expenditure during the rest session was estimated and the energy cost of exercise was measured by indirect calorimetry. Relative energy intake was calculated by subtracting the energy expenditure of the exercise session from the energy intake of the test meal. Post-meal hedonic ratings were completed after lunch. Energy intake and relative energy intake increased during high-fat conditions compared with the low-fat, independently of exercise (P < 0·001). There was a positive relationship between dietary restraint scores and energy intake or relative energy intake in the rest conditions only (r 0·54, P < 0·01). The decrease of relative energy intake between the rest and exercise conditions was higher in restrained than in unrestrained eaters (P < 0·01). These results confirm that a high-fat diet reversed the energy deficit due to exercise. There was no energy compensation in response to an acute bout of exercise during the following meal. In restrained eaters, exercise was more effective in creating an energy deficit than in unrestrained eaters. Exercise may help restrained eaters to maintain control over appetite.