Sensory and hedonic judgments of common foods by lean consumers and consumers with obesity

Finding the Sweet Spot: Measurement, Modification, and Application of Sweet Hedonics in Humans

Sweetness is a sensation that contributes to the palatability of foods, which is the primary driver of food choice. Thus, understanding how to measure the appeal (hedonics) of sweetness and how to modify it are key to effecting dietary change for health. Sweet hedonics is multidimensional so can only be captured by multiple approaches including assessment of elements such as liking, preference, and consumption intent. There are both innate and learned components to the appeal of sweet foods and beverages. These are responsive to various behavioral and biological factors, suggesting the opportunity to modify intake. Given the high amount of added sugar intake in the United States and recommendations from many groups to reduce this, further exploration of current hypothesized approaches to moderate sugar intake (e.g., induced hedonic shift, use of low-calorie sweeteners) is warranted.

Food Preferences and Obesity

Obesity is a multifactorial disease with several potential causes that remain incompletely understood. Recent changes in the environment, which has become increasingly obesogenic, have been found to interact with individual factors. Evidence of the role of taste responsiveness and food preference in obesity has been reported, pointing to a lower taste sensitivity and a higher preference and intake of fat and, to a lesser extent, sweet foods in obese people. Studies in the last decades have also suggested that individual differences in the neurophysiology of food reward may lead to overeating, contributing to obesity. However, further studies are needed to confirm these findings. In fact, only a limited number of studies has been conducted on large samples, and several studies were conducted only on women. Larger balanced studies in terms of sex/gender and age are required in order to control the confounding effect of these variables. As many factors are intertwined in obesity, a multidisciplinary approach is needed. This will allow a better understanding of taste alteration and food behaviours in obese people in order to design more effective strategies to promote healthier eating and to prevent obesity and the related chronic disease risks.

Taste Sensitivity Is Associated with Food Consumption Behavior but not with Recalled Pleasantness

As taste perception varies between individuals, it might be important in explaining food consumption behavior. Previous studies have focused on sensitivity to the bitter tastant PROP (6-n-propylthiouracil) concerning eating with little attention paid to other tastants. For the first time, connections between food consumption behavior, pleasantness, and taste sensitivity are studied with five taste modalities. Sensitivity to bitterness, sourness, umami, saltiness, and sweetness as well as an overall taste sensitivity score was determined with intensity evaluation for 199 Finnish adults. Recalled pleasantness and food consumption behavior were enquired with online questionnaires. Consumption concerned intake of vegetables, fruits, and berries; use-frequency of specific foods; and tendency to mask or modify tastes of foods. All modality-specific taste sensitivities were related to some consumption behavior but none to recalled pleasantness. A higher taste sensitivity score indicated avoidance of coffee, lower consumption of pungent foods, and a more frequent habit of adding ketchup to a meal. In conclusion, it may be more informative to study the influence of taste sensitivity on food consumption behavior with taste modalities separately rather than with a general indicator of taste sensitivity. Additionally, these results highlight the importance of studying actual behavior toward food and not just liking.

Appetitive Pavlovian-to-Instrumental Transfer in Participants with Normal-Weight and Obesity

Altered eating behavior due to modern, food-enriched environments has a share in the recent obesity upsurge, though the exact mechanisms remain unclear. This study aims to assess whether higher weight or weight gain are related to stronger effects of external cues on motivation-driven behavior. 51 people with and without obesity completed an appetitive Pavlovian-to-Instrumental Transfer (PIT) paradigm. During training, button presses as well as presentation of fractal images resulted in three palatable and one neutral taste outcome. In the subsequent test phase, outcome-specific and general behavioral bias of the positively associated fractal images on deliberate button press were tested under extinction. While all participants showed signs of specific transfer, general transfer was not elicited. Contrary to our expectations, there was no main effect of weight group on PIT magnitude. Participants with obesity exhibited higher scores in the Three-Factor Eating Questionnaire Disinhibition scale, replicating a very robust effect from previous literature. Individual Restraint scores were able to predict body-mass index (BMI) change after a three-year period. Our data indicate that PIT is an important player in how our environment influences the initiation of food intake, but its effects alone cannot explain differences in-or future development of-individual weight.

Dietary taste patterns by sex and weight status in the Netherlands

Taste is a key driver of food choice and intake. Taste preferences are widely studied, unlike the diet's taste profile. This study assessed dietary taste patterns in the Netherlands by sex, BMI, age and education. A taste database, containing 476 foods' taste values, was combined with 2-d 24-h recalls in two study populations. The percentage of energy intake from six taste clusters was assessed in the Dutch National Food Consumption Survey (DNFCS 2007-2010; n 1351) and in an independent observational study: the Nutrition Questionnaires plus (NQplus) study (2011-2013; n 944). Dietary taste patterns were similar across study populations. Men consumed relatively more energy from 'salt, umami and fat' (DNFCS; 24 % energy, NQplus study; 23 %)- and 'bitter' (7 %)-tasting foods compared with women (21 %, P<0·001, 22 %, P=0·005; 3 %, P<0·001, 4 %, P<0·001, respectively). Women consumed more % energy from 'sweet and fat' (15 %)- and 'sweet and sour' (13 %, 12 %, respectively)-tasting foods compared with men (12 %, P<0·001, 13 %, P=0·001; 10 %, P<0·001). Obese individuals consumed more % energy from 'salt, umami and fat'- and less from 'sweet and fat'-tasting foods than normal-weight individuals ('salt, umami and fat', men; obese both studies 26 %, normal-weight DNFCS 23 %, P=0·037, NQplus 22 %, P=0·001, women; obese 23 %, 24 %, normal weight 20 %, P=0·004, P=0·011, respectively, 'sweet and fat', men; obese 11 %, 10 %, normal weight 13 %, P<0·05, 14 %, P<0·01, women; obese 14 %, 15 %, normal weight 16 %, P=0·12, P=0·99). In conclusion, our taste database can be used to deepen our understanding of the role of taste in dietary intake in the Netherlands by sex, BMI, age and education.

Wanting and liking: Separable components in problematic eating behavior?

Some individuals may have an addictive-like response to certain foods, possibly contributing to problematic eating. Highly processed foods, with added fats and/or refined carbohydrates, are suggested to be most associated with addictive-like eating. The incentive sensitization theory suggests that wanting (e.g. craving) may drive compulsive drug use rather than liking (e.g. enjoyment), but it is unknown whether highly processed foods elicit similar wanting and liking patterns as drugs of abuse, or whether individual differences exist. The current study examines the association of highly processed foods with craving and liking, and whether these relationships differ by food addiction symptomology, cognitive restraint, or body mass index (BMI). Participants (n = 216) reported craving and liking for 35 foods and completed the Yale Food Addiction Scale (YFAS) and Three Factor Eating Questionnaire (TFEQ). Highly processed foods were craved more overall. Craving of highly processed foods was predicted negatively by restraint and positively by YFAS score. Liking of highly processed foods was predicted negatively by restraint and positively by BMI. In conclusion, craving and liking appear distinct with respect to highly processed foods, and may be influenced by addictive-like eating, cognitive restraint, and BMI. This suggests that the incentive sensitization framework may also be relevant for problematic food consumption, especially for individuals reporting food addiction symptoms.

Associations between liking for fat, sweet or salt and obesity risk in French adults: a prospective cohort study

BACKGROUND

Individual sensory liking appears to be an important determinant of dietary intake and may consequently influence weight status. Cross-sectional studies have shown positive association between fat liking and weight status and equivocal results regarding salt and sweet liking. Moreover, the contribution of dietary intake to explain this relationship has not been studied yet. We investigated the prospective association between sensory liking for fat, sweet or salt and the onset of obesity over 5 years in adults, and the mediating effect of dietary intake.

METHODS

We prospectively examine the risk of obesity among 24,776 French adults participating in the NutriNet-Santé cohort study. Liking scores and dietary data were assessed at baseline using a validated web-based questionnaire and 24 h records, respectively. Self-reported anthropometric data were collected using web-based questionnaire, each year during 5 years. Associations between quartiles of liking for fat, sweet or salt and obesity risk, and the mediating effect of diet were assessed by multivariate Cox proportional hazards models stratified by gender, adjusted for sociodemographic and lifestyle factors.

RESULTS

In both genders, sensory liking for fat was associated with an increased risk of obesity (hazard ratios for quartile 4 compared to quartile 1, men: HR(Q4vs.Q1) = 2.39 (95% CI 1.39,4.11) P-trend = 0.0005, women: HR(Q4vs.Q1) = 2.02 (1.51,2.71) P-trend = <0.0001). Dietary intake explained 32% in men and 52% in women of the overall variation of liking for fat in obesity. Sensory liking for sweet was associated with a decreased risk of obesity (men: HR(Q4vs.Q1) = 0.51 (0.31,0.83) P-trend = 0.01, women: HR(Q4vs.Q1) = 0.72 (0.54,0.96) P-trend = 0.035). No significant association between salt liking and the risk of obesity was found.

CONCLUSIONS

Unlike sweet and salt liking, higher liking for fat appears to be a major risk factor of obesity, largely explained by dietary intake. Our findings emphasize the need to centrally position sensory liking in obesity prevention.

Cross-modal interactions for custard desserts differ in obese and normal weight Italian women

The effects of variation in odors and thickening agents on sensory properties and acceptability of a model custard dessert were investigated in normal weight and obese women. Subjects rated their liking and the intensity of sensory properties (sweetness, vanilla and butter flavors, and creaminess) of 3 block samples (the first varied in vanilla aroma, the second varied in butter aroma and the third varied in xanthan gum). Significant differences were found in acceptability and intensity ratings in relation to body mass index. The addition of butter aroma in the custard was the most effective way to elicit odor-taste, odor-flavor and odor-texture interactions in obese women. In this group, butter aroma, signaling energy dense products, increased the perception of sweetness, vanilla flavor and creaminess, which are all desirable properties in a custard, while maintaining a high liking degree. Understanding cross-modal interactions in relation to nutritional status is interesting in order to develop new food products with reduced sugar and fat, that are still satisfying for the consumer. This could have important implications to reduce caloric intake and tackle the obesity epidemic.

How much sugar do consumers add to plain yogurts? Insights from a study examining French consumer behavior and self-reported habits

In France, 50% of consumers sweeten plain yogurts prior to consumption. This study measured how much sugar consumers added under contextualized testing conditions. Participants (199 French adults who regularly consume plain yogurt adding sugar) were given a plain yogurt (125 g) at the end of a full meal and were allowed to sweeten it with their usual sweetener (caster sugar, honey, or jam). The quantities added were measured indirectly by weighing the sweetener containers before and after use; they were then converted into equivalent quantities of sucrose, or "added sugar." Participants were asked to describe their relative hunger, thirst, and liking for plain yogurt and to estimate the quantity of sweetener they had added. On average, participants added 13.6 g of sugar to their yogurts, which is higher than the 10.2 g of sugar contained in pre-sweetened commercial yogurts (125 g). More sugar was added when subjects used jam (24.4 g/yogurt, n = 36) as opposed to caster sugar (11.0 g/yogurt, n = 134) or honey (12.1 g/yogurt, n = 29). Age, socio-professional category, and BMI had a significant influence on added-sugar quantity. Based on behavior and attitude, participants could be separated into three evenly sized groups: "low sugar users" (n = 67, median = 6.1 g/yogurt), who tended to control their food intake, "medium sugar users" (n = 66, median = 11.4 g/yogurt), and "heavy sugar users" (n = 66, median = 19.9 g/yogurt) who sought immediate satisfaction. To our knowledge, this study is the first to provide robust data on the amount of sugar consumers add to plain yogurts in contextualized conditions (self preparation during a real meal). Our findings show that consumers underestimated by half the quantity of sweetener they added.

Is it Worth the Effort? Novel Insights into Obesity-Associated Alterations in Cost-Benefit Decision-Making

Cost-benefit decision-making entails the process of evaluating potential actions according to the trade-off between the expected reward (benefit) and the anticipated effort (costs). Recent research revealed that dopaminergic transmission within the fronto-striatal circuitry strongly modulates cost-benefit decision-making. Alterations within the dopaminergic fronto-striatal system have been associated with obesity, but little is known about cost-benefit decision-making differences in obese compared with lean individuals. With a newly developed experimental task we investigate obesity-associated alterations in cost-benefit decision-making, utilizing physical effort by handgrip-force exertion and both food and non-food rewards. We relate our behavioral findings to alterations in local gray matter volume assessed by structural MRI. Obese compared with lean subjects were less willing to engage in physical effort in particular for high-caloric sweet snack food. Further, self-reported body dissatisfaction negatively correlated with the willingness to invest effort for sweet snacks in obese men. On a structural level, obesity was associated with reductions in gray matter volume in bilateral prefrontal cortex. Nucleus accumbens volume positively correlated with task induced implicit food craving. Our results challenge the common notion that obese individuals are willing to work harder to obtain high-caloric food and emphasize the need for further exploration of the underlying neural mechanisms regarding cost-benefit decision-making differences in obesity.

Students' Consumption of Beverages and Snacks at School and Away from School: A Case Study in the North East of Italy

In North-East Italy (the Veneto region), several public school nutrition policies have been developed to reduce the consumption of high-caloric snacks and beverages. However, little is known about whether the policies actually influence students’ dietary behaviors. In order to address this point, a multi-center cross-sectional survey of 691 Italian students was conducted. Students completed the Beverage and Snack Questionnaire, which assesses the consumption of beverages and snacks at school and out of school. Three-level Poisson Models with random intercept with students (level 1 units) nested into classroom (level 2 units), and nested into schools (level 3 units), were used to examine the influence of the school setting vs. the out of school environment (independent variable) on students’ consumption of sweet beverages, snacks, milk-based beverages, low-carbohydrate drinks, fruit, and vegetables (dependent variable) (p ≤ 0.05). The results showed a significantly higher consumption of sweet beverages, snacks, milk-based beverages, low-carbohydrate drinks, fruit, and vegetables out-of-the school, suggesting a school-protective association Thus, the policies aimed to limit or deny access to unhealthy foods in the school environment may play an important role in promoting more healthful dietary patterns for school children. Additional studies should be conducted to compare students’ dietary behaviors between schools with nutrition policies to those without nutrition policies.

Associations between weight status and liking scores for sweet, salt and fat according to the gender in adults (The Nutrinet-Santé study)

BACKGROUND/OBJECTIVES

As taste preferences may be associated with obesity, the present study investigated whether obese subjects presented heightened liking for the sensations of sweet, salt and fat.

SUBJECTS/METHODS

Liking scores were determined by a questionnaire including 83 items on liking for sweet or fatty foods, and the preferred extent of seasoning with salt, sweet or fat. Data from 46909 adults included in the French web-based observational cohort of the Nutrinet-Santé study were collected and weighted according to the national population census. Relationships between liking scores and body mass index (BMI) as categorical or linear explanatory variable were assessed separately by gender using covariance and linear regression analyses, adjusted for age, education level, living area, smoking and alcohol.

RESULTS

Overall liking scores for salt and fat were linearly positively linked to BMI in men and women (P≤0.001) and were higher in obese than in normal-weight individuals. The score difference between BMI categories was greater in women for fat liking only. For sweet liking, results differed between gender and compounding factors. Liking for added sugar and sweet foods was positively linked to BMI in women unlike in men; liking for natural sweetness was negatively linked to BMI in both genders.

CONCLUSIONS

This study demonstrates that the relationship between liking and BMI differs according to the gender in its magnitude for fat and in its nature for sweet, unlike that for salt. Liking for sweet and fat may be linked to overconsumption of the corresponding foods, especially in women. This warrants further investigation.

The association of food characteristics and individual differences with ratings of craving and liking

Craving and liking are related to eating-related problems, but less is known about the association of specific food characteristics (e.g., sugar, fat) with craving/liking. The relation of individual differences in eating behavior with these craving and liking patterns is also relatively unknown. We examine the nomothetic impact of sugar, fat and processing on food craving and liking and the moderation of these effects by idiographic factors (e.g., Body Mass Index [BMI], hunger). One hundred and five overweight and obese women completed craving and liking ratings on 180 foods that differed in levels of sugar, fat and processing. Food craving was linked positively to fat content, but negatively to sugar. Food liking was associated negatively with sugar content and processing level. Addictive-like eating predicted elevated overall food craving and liking, and increased craving and liking for processed foods. Attempted restriction efforts were unrelated to craving and liking. BMI was associated with less craving for fattier foods and lower liking for the average food. Hunger was associated with increased craving for the average food. These findings highlight the role of fat in cravings and differences in craving and liking based on BMI, loss of control over eating, and hunger. These findings are relevant to theories of problematic eating and the development of eating-related interventions.

Increased sensitivity to food cues in the fasted state and decreased inhibitory control in the satiated state in the overweight

BACKGROUND

Flexibility of food reward-related brain signaling (FRS) between food and nonfood stimuli may differ between overweight and normal-weight subjects and depend on a fasted or satiated state.

OBJECTIVE

The objective was to assess this flexibility in response to visual food and nonfood cues.

DESIGN

Twenty normal-weight [mean ± SEM BMI (in kg/m(2)) = 22.7 ± 0.2; mean ± SEM age = 22.4 ± 0.4 y] and 20 overweight (BMI = 28.1 ± 0.3; age = 24.0 ± 0.7 y) participants completed 2 fMRI scans. Subjects arrived in a fasted state and consumed a breakfast consisting of 20% of subject-specific energy requirements between 2 successive scans. A block paradigm and a food > nonfood contrast was used to determine FRS.

RESULTS

An overall stimulus × condition × subject group effect was observed in the anterior cingulate cortex (ACC) (P < 0.006, F((1,38)) = 9.12) and right putamen (P < 0.006, F((1,38)) = 9.27). In all participants, FRS decreased from the fasted to the satiated state in the cingulate (P < 0.005, t((39)) = 3.15) and right prefrontal cortex (PFC) (P < 0.006, t((39)) = 3.00). In the fasted state, they showed FRS in the PFC (P < 0.004, t((39)) = 3.17), left insula (P < 0.009, t((39)) = 2.95), right insula (P < 0.005, t((39)) = 3.12), cingulate cortex (P < 0.004, t((39)) = 3.21), and thalamus (P < 0.006, t((39)) = 2.96). In the satiated state, FRS was limited to the left insula (P < 0.005, t((39)) = 3.21), right insula (P < 0.006, t((39)) = 3.04), and cingulate cortex (P < 0.005, t((39)) = 3.15). Regarding subject group, in the fasted state, FRS in the ACC was more pronounced in overweight than in normal-weight subjects (P < 0.005, F((1,38)) = 9.71), whereas in the satiated state, FRS was less pronounced in overweight than in normal-weight subjects in the ACC (P < 0.006, F((1,38)) = 9.18) and PFC (P < 0.006, F((1,38)) = 8.86), which suggests lower inhibitory control in the overweight.

CONCLUSION

FRS was higher in the overweight in the satiated state; however, when sufficiently satiated, the overweight showed decreased inhibitory control signalling, which facilitates overeating. This trial was registered in the Dutch clinical trial register as NTR2174.

Nonnutritive sweetener consumption in humans: effects on appetite and food intake and their putative mechanisms

Nonnutritive sweeteners (NNS) are ecologically novel chemosensory signaling compounds that influence ingestive processes and behavior. Only about 15% of the US population aged >2 y ingest NNS, but the incidence is increasing. These sweeteners have the potential to moderate sugar and energy intakes while maintaining diet palatability, but their use has increased in concert with BMI in the population. This association may be coincidental or causal, and either mode of directionality is plausible. A critical review of the literature suggests that the addition of NNS to non-energy-yielding products may heighten appetite, but this is not observed under the more common condition in which NNS is ingested in conjunction with other energy sources. Substitution of NNS for a nutritive sweetener generally elicits incomplete energy compensation, but evidence of long-term efficacy for weight management is not available. The addition of NNS to diets poses no benefit for weight loss or reduced weight gain without energy restriction. There are long-standing and recent concerns that inclusion of NNS in the diet promotes energy intake and contributes to obesity. Most of the purported mechanisms by which this occurs are not supported by the available evidence, although some warrant further consideration. Resolution of this important issue will require long-term randomized controlled trials.

Influence of Nutrition Attitudes and Motivators for Eating on Postpartum Weight Status in Low-Income New Mothers

OBJECTIVE

The purpose of this study was to identify attitudes about nutrition and their influence on weight status in low-income mothers in the first year postpartum.

DESIGN

Nutrition attitudes were assessed at 1.5, 6, and 12 months postpartum. Body weight was measured at each time point and height at 1.5 months to calculate body mass index. Nutrition attitudes at each time were compared with demographic variables and weight status.

SUBJECTS

Subjects were 340 non-Hispanic white (31.3%), non-Hispanic black (25.1%), and Hispanic (43.7%) new mothers (mean age=22.4 years) located in central Texas. Criteria for participation included good health at delivery and low income (</=185% federal poverty guideline).

STATISTICAL ANALYSES

chi(2) tests were used to compare demographic groups to categorical variables. Multivariate analysis of variance was done to investigate the effect of demographic variables on instrument subscale scores. A repeated-measures analysis of variance was used to identify significant changes over time.

RESULTS

Obese women had higher barriers to healthful eating subscale means at 1 year compared with normal and overweight subjects at 1.5 and 6 months, and had more barriers than overweight participants at 12 months. Obese individuals also had higher emotional eating subscale scores than did overweight women at 1.5 months and both normal and overweight subjects at 12 months.

CONCLUSIONS

Women who were obese at 1 year postpartum were more likely to perceive more barriers to healthful eating and respond more to emotional cues to eat. Health professionals could emphasize potential changes and difficulties often faced in postpartum and identify techniques to overcome these obstacles to healthful eating.

Psychophysics of sweet and fat perception in obesity: problems, solutions and new perspectives

Psychophysical comparisons seem to show that obese individuals experience normal sweet and fat sensations, they like sweetness the same or less, but like fat more than the non-obese do. These psychophysical comparisons have been made using scales (visual analogue or category) that assume intensity labels (e.g. extremely) which denote the same absolute perceived intensity to all. In reality, the perceived intensities denoted by labels vary because they depend on experiences with the substances to be judged. This variation makes comparisons invalid. Valid comparisons can be made by asking the subjects to rate their sensory/hedonic experiences in contexts that are not related to the specific experiences of interest. Using this methodology, we present the evidence that the sensory and hedonic properties of sweet and fat vary with body mass index. The obese live in different orosensory and orohedonic worlds than do the non-obese; the obese experience reduced sweetness, which probably intensifies fat sensations, and the obese like both sweet and fat more than the non-obese do. Genetic variation as well as taste pathology contribute to these results. These psychophysical advances will impact experimental as well as clinical studies of obesity and other eating disorders.

Eating for pleasure or just wanting to eat? Reconsidering sensory hedonic responses as a driver of obesity

Pleasure from foods can stimulate "non-homoeostatic" eating, and might therefore also potentially contribute toward obesity. However, obesity is not reliably associated with heightened hedonic responses to foods. This apparent discrepancy may reflect the differentiation between "liking" and "wanting". Supporting this, behavioural and neurophysiological data on responsiveness to food-related cues indicate that obesity may be associated with increased motivation for food consumption, without necessarily any greater explicit pleasure derived from the orosensory experience of eating. This distinction may have important implications for further research, and applications in commercial and public health approaches to modifying energy intakes.

Effect of Roux-en-Y gastric bypass on satiety and food likes: the role of genetics

Among factors influencing the outcome of bariatric surgery may be genetics and familial risk. The purpose of this study was to assess the etiology of obesity and its impact on hunger, satiety, and food likes in obese patients undergoing Roux-en-Y gastric bypass (RYGB). This study was based on 76 patients undergoing RYGB procedures performed by a single surgeon. A previously described 100-point obesity risk index (ORI) was used to assess familial obesity risk. Hunger and satiety were assessed using a standardized Visual Analog Scale "Snickers" test, and food preferences for regular vs. low-fat potato chips were measured preoperatively and postoperatively. Patients were stratified preoperatively into high ORI (n = 34) and low ORI (n = 42) groups. Before operation, high-ORI patients preferred high-fat (regular) potato chips to low-fat (baked) potato chips, whereas the low-ORI patients liked both food types equivalently (P < 0.05). After operation (n = 43), both groups showed lower preferences for high-fat potato chips (P < 0.05 for high-ORI group). As anticipated, hunger was dramatically suppressed after RYGB. However, there was more satiety in the high-ORI group (P < 0.05, ANOVA). Most patients undergoing bariatric surgery had a strong familial or genetic component to their disease. RYGB in high-ORI patients was associated with a significant decline in preference of fatty food and a significantly prolonged drop in hunger ratings after a fast and after a standard 282 kcal meal. The success of bariatric surgery may be influenced by the etiology of obesity.

Sensory experience of food and obesity: a positron emission tomography study of the brain regions affected by tasting a liquid meal after a prolonged fast

The sensory experience of food is a primary reinforcer of eating and overeating plays a major role in the development of human obesity. However, whether the sensory experience of a forthcoming meal and the associated physiological phenomena (cephalic phase response, expectation of reward), which prepare the organism for the ingestion of food play a role in the regulation of energy intake and contribute to the development of obesity remains largely unresolved. We used positron emission tomography (PET) and 15O-water to measure changes in regional cerebral blood flow (rCBF) and to assess the brain's response to the oral administration of 2 ml of a liquid meal (Ensure Plus, 1.5 kcal/ml) after a 36-h fast and shortly before consuming the same meal. Twenty-one obese (BMI > 35 kg/m2, 10M/11F, age 28 +/- 6 years, body fat 40 +/- 6%) and 20 lean individuals (BMI < 25 kg/m2, 10M/10F, age 33 +/- 9 years, body fat 21 +/- 7%) were studied. Compared to lean individuals, obese individuals had higher fasting plasma glucose (83.3 +/- 6.2 vs. 75.5 +/- 9.6 mg/dl; P = 0.0003) and insulin concentrations (6.1 +/- 3.5 vs. 2.5 +/- 1.7 microU/ml; P < 0.0001) and were characterized by a higher score of dietary disinhibition (i.e., the susceptibility of eating behavior to emotional factors and sensory cues, 5.7 +/- 3.6 vs. 3.5 +/- 2.7; P = 0.01) assessed by the Three Factor Eating Questionnaire. In response to the sensory experience of food, differences in rCBF were observed in several regions of the brain, including greater increases in the middle-dorsal insula and midbrain, and greater decreases in the posterior cingulate, temporal, and orbitofrontal cortices in obese compared to lean individuals (P < 0.05, after small volume correction). In a multiple regression model, percentage of body fat (P = 0.04), glycemia (P = 0.01), and disinhibition (P = 0.07) were independent correlates of the neural response to the sensory experience of the meal in the middle-dorsal insular cortex (R2 = 0.45). We conclude that obesity is associated with an abnormal brain response to the sensory aspects of a liquid meal after a prolonged fast especially in areas of the primary gustatory cortex. This is only partially explained by the elevated glycemia and high level of disinhibition which characterize individuals with increased adiposity. These results provide a new perspective on the understanding of the neuroanatomical correlates of abnormal eating behavior and their relationship with obesity in humans.

From milk to solids: a reference standard for the transitional eating process in infants and preschool children in Japan

OBJECTIVE

This paper aims to establish a potential reference standard for the process of transition from milk to solid food in infants and preschool children in Japan, using the transitional food process (TFP) scale described by Sakashita et al. The background for variation and delay in the process are also discussed.

DESIGN

A randomized sample survey covering entire Japan.

SETTING

Mailing self-completion of questionnaires.

SUBJECTS

Randomized sample of 14 000 children aged 0-6 y and their family from 13 prefectures in Japan, namely Hokkaido, Aomori, Iwate, Niigata, Tokyo, Saitama, Fukui, Nagano, Nagoya, Hyogo, Yamaguchi, Kagoshima, and Okinawa.

METHODOLOGY

Questionnaires requesting the TFP scale and background factors were sent to 14,000 children and families. The percentile ages were calculated. An eating ability index (EAI: number of accepted foods/total number of foods) x 100) was calculated. Regression analysis by analysis of covariance (ANCOVA; SPSS, 1997) was used to determine the influence of background factors on EAI.

RESULTS

From the 6747 (48.2%) effective answers received, percentile curves of the acceptability of each food on the scale were drawn, and used as initial reference standards. The 50 percentile age range of these 20 standard foods covers from 5 to 42 months after birth. The sensitive period for increasing the acceptance of foods in children was between 6 months and 2(1/2) y of age. ANCOVA regression model (R2=0.605) showed that EAI was mostly influenced by age (P=0.000), followed by feeding style (P=0.000), infant food preparation (P=0.000), information source (P=0.000), and birth order (P=0.003). The dominant cause of digestive system problems was shown to be infection, not too-hard food. It seems that breast feeding, bottle feeding with chewing-type nipples, and the manner of preparing infant foods from the family table promote the progress in acceptance. Children whose mothers followed the information given in books or magazines showed a slower progress.

CONCLUSIONS

It seems appropriate to use this reference standard in the study of the transitional process from milk to solid food in infants and preschool children in Japan.

Taste preferences and body weight changes in an obesity-prone population

BACKGROUND

Taste preferences for highly palatable foods rich in sugar and fat may underlie the current epidemic of obesity.

OBJECTIVE

This study aimed to determine whether the hedonic response to sweet and creamy solutions differs between whites and Pima Indians and whether a preference for these tastes predicts weight gain.

DESIGN

One hundred twenty-three Pima Indian and 64 white volunteers taste tested solutions of nonfat milk (0.1% fat), whole milk (3.5% fat), half and half (11.3% fat), and cream (37.5% fat) containing 0%, 5%, 10%, or 20% sugar by weight. Solutions were rated for perceived sweetness, creaminess, and pleasantness (hedonic response) on a 100-mm visual analogue scale. Follow-up body weight was measured in 75 Pima Indians 5.5 +/- 3.0 y ( +/- SD) after baseline taste testing.

RESULTS

The Pima Indians had a significantly (P = 0.006) lower hedonic response than did the whites (repeated-measures analysis of variance). Neither body size (P = 0.56) nor adiposity (P = 0.86) was a significant predictor of the hedonic response. There was a positive correlation (r = 0.28, P = 0.01) between the maximal hedonic response at baseline and subsequent weight gain in the Pima Indians.

CONCLUSION

Although the Pima Indians liked sweet and creamy solutions less than the whites did, a heightened hedonic response for these solutions among the Pima Indians was associated with weight gain.

Psychological and behavioral correlates of baseline BMI in the diabetes prevention program (DPP)

OBJECTIVE

To determine psychological and behavioral correlates of baseline BMI in the Diabetes Prevention Program (DPP).

RESEARCH DESIGN AND METHODS

Of 1,079 DPP lifestyle intervention participants, 274 completed validated questionnaires at baseline assessing weight loss history, stage of change, self-efficacy, dietary restraint, emotional eating, binge eating, perceived stress, depression, and anxiety.

RESULTS

The mean age of subjects was 52.5 years, 65% were women, and their mean BMI was 33.9 kg/m(2). Higher BMI correlated with more frequent weight cycling (r = 0.50, P < 0.0001) and efforts at weight loss (r = 0.34, P < 0.0001); younger age when first overweight (r = -0.42, P < 0.0001); lower exercise efficacy (r = -0.15, P = 0.015); lower weight loss efficacy (r = -0.21, P < 0.001); a less advanced stage of change for weight loss (r = -0.12, P = 0.04); more perceived stress (r = 0.14, P = 0.02); emotional eating (r = 0.19, P = 0.001); poor dietary restraint (r = -0.14, P = 0.02); binge eating frequency (r = 0.18, P = 0.004) and severity (r = 0.30, P < 0.0001); feeling deprived, angry, or upset while dieting (r = 0.27, P </= 0.0001); and food cravings while dieting (r = 0.31, P < 0.0001). Correlations did not differ as a function of sex; however, correlations of BMI with anxiety and low-fat diet and weight loss self-efficacy differed as a function of ethnicity. In multivariate models, binge eating severity, poor dietary restraint, and food craving were independent correlates of baseline BMI.

CONCLUSIONS

Many psychological and behavioral factors are associated with higher BMI in this ethnically diverse group of men and women. Whether strategies that help patients increase levels of dietary restraint and reduce binge eating and food craving lead to long-term weight loss maintenance needs longitudinal study.

Determinants of food choice: relationships with obesity and weight control

The decision to eat, and to eat particular foods, varies for different individuals and situations. Individual differences in food likes and desires develop throughout life because of differing food experiences and attitudes. There are many internal and external cues, not just stimulation from foods or hunger, which can trigger the immediate desire to eat or orient eating toward certain foods. Food desires and intake are an outcome of interactions between these cues and more stable individual physiological and psychological characteristics. Overweight and obese individuals show a tendency toward greater liking and selection of energy-dense foods, which may contribute to development and maintenance of these conditions. However, although liking (pleasure from eating) is an important part of food choice, it may make only a modest contribution to overall variation in food choice and eating behaviors. Indeed, difficulties of weight control may reflect problems with cues and motivations to eat, rather than with heightened pleasure derived from eating. Paradoxically, individuals highly concerned with food intake and weight control may be particularly susceptible to thoughts, emotions, and situational cues that can prompt overeating and undermine their attempts to restrain eating. Repeat dieting, high day-to-day fluctuations in intakes, and attempts to enforce highly rigid control over eating all seem to be counterproductive to weight control efforts and may disrupt more appropriate food choice behaviors. Longer-term weight maintenance solutions and programs that offer a degree of structuring of the personal food environment, while retaining flexibility in choices, therefore, may be particularly beneficial in weight management.