Among the key characteristics of the Western obesogenic food environment is a highly palatable and varied food supply. Laboratory investigations of eating behavior in both humans and animals established key roles for palatability and variety in stimulating appetite, delaying satiety, and promoting excessive energy intake. There is a robust effect of food palatability and variety on short-term food intake, and increased variety and palatability Two palatable chap cause weight gain in animal models.
However, laboratory paradigms do not replicate the complexities of eating in a natural setting, and there is a shortage of evidence to estimate the magnitude of effects on weight in humans.
There are substantial individual differences in susceptibility to the palatability effect and this may be a key determinant in individual vulnerability to weight gain. The understanding of pathways through which palatability and variety can affect Two palatable chap is advancing, and epidemiologic and intervention studies are needed to translate laboratory findings into applications in public health or clinical domains, and to establish whether there is a role for greater regulation of the food environment in tackling increases in obesity.
Environmental increases in palatability and variety in the food supply are potential contributors to the rise in adiposity seen worldwide. Both developed and developing countries have seen increasing diversity in the food supply, with a decline in the consumption Two palatable chap staples, such as cereals, and increased consumption of a variety of more palatable foods including meat, fish, sugar, and vegetable fats 12. The increasing dominance of supermarkets, which offer greater variety to the consumer, together with the proliferation Two palatable chap convenience foods engineered for maximum palatability, are among the many social, economic, and cultural factors contributing to these trends 3.
In susceptible individuals, such environmental changes may be triggers for overconsumption leading to obesity 4 — 8.
Although all consumers are Two palatable chap to high and rising levels of food variety and palatability, exposure to these features of the food environment vary by social, economic, and cultural groupings, individual lifestyle, and purchasing decisions 9 — The impact of environmental exposures are further moderated by genetic and acquired characteristics, with some individuals being more vulnerable to aspects of the food environment that enhance appetite and delay satiety 613 — This review will summarize evidence for the influence of variety and palatability on appetite, intake, and weight gain, and discuss future research directions to translate the scientific work into public health and clinical applications.
The sensory properties of foods primarily taste and smell are highly influential in motivating food selection 51819indicating a central role for palatability in determining eating behavior. In evolutionary terms, human taste preferences were shaped by the need to seek out foods that are high in energy, which can explain the Two palatable chap appeal of sugars and fats A review of human laboratory studies showed that greater palatability is reliably translated into higher short-term intake 21and effects are seen even when the nutritional composition of the food is held constant 22 — Two palatable chap studies also showed that people eat more when food is palatable.
However, these studies did not test cause—effect relations by varying meal palatability systematically to examine effects on intake.
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Palatable foods are thought to influence intake through the activation of hedonic motivational pathways 627 Palatability has a greater effect on intake in a satiated state than in a hungry state 29suggesting that although homeostatic mechanisms dominate in the hungry state, hedonic mechanisms become more important once homeostatic needs are met.
However, studies that measured liking for foods distinct Two palatable chap wanting to eat them reported that ratings for liking are higher when hungry, indicating some overlap between the hedonic and homeostatic motivation to eat 30 — Exposure to palatable foods reliably increases self-reported appetite, with ratings of hunger actually increasing during the early stages of a highly palatable meal 22 Some studies also found faster recovery of appetite following a more palatable meal 3334suggesting that later compensation for increased intake may be less likely following a palatable meal.
A wider effect of palatable food on hedonic responsiveness is suggested by animal studies. Consumption of palatable foods can induce striatal dopamine transmission deficits 4and over time consumption of a highly palatable diet may lead to reductions in brain reward response capacity. Hence it has been suggested that these acquired alterations in reward sensitivity can augment stimulation-seeking, resulting in an increasing tendency to overeat palatable food Cognitive factors were shown to modulate sensory perceptions in Two palatable chap 5.
Human eating behavior is also strongly influenced by food availability, social and cultural norms, and health and appearance considerations 3839and reward value may not always be the main factor determining intake in situations in Two palatable chap social, cultural, and food environment factors exert their own pressures. If highly palatable foods increase intake in the short term, do they increase weight in the long term?
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In humans, no studies have systematically manipulated dietary palatability to examine long-term effects on weight. There is a similar lack of epidemiologic studies examining associations between exposure to more palatable diets and weight change, meaning that direct effects on weight in humans remain untested.
Although most studies look at normative effects, i. One of the earliest laboratory studies of individual differences in eating behavior 44 showed that obese participants ate more highly palatable food than normal-weight participants, but there were no differences for less palatable food.
Introduction: Defining the Issue
This was replicated in a number of subsequent laboratory studies 4546and a graded association between obesity and the palatability effect was demonstrated 47 Observational studies of eating behavior also showed an interaction between weight and the presence of palatable food in predicting overeating Much of the work to understand the nature Two palatable chap vulnerability to food environments used psychometric measures of eating style to index differential responsiveness to food stimuli.
Individuals scoring high on these dimensions might be expected to be particularly vulnerable to a highly palatable food environment.
Similar scales for children the food responsiveness scale of the Child Eating Behavior Questionnaire and infants the Baby Eating Behavior Questionnaire also demonstrate individual variation 51 Twin and family Two palatable chap using Two palatable chap measures found strong evidence for heritability of food responsiveness the tendency to eat when prompted by sensory cues in both adults and children, indicating that there may be a biologic basis for variation in this trait 52 — Greater food responsiveness is linked with higher body weight in cross-sectional studies in children 58 and a recent prospective study showed that higher food responsiveness in infancy predicts greater weight gain from 3 to 15 mo In adults, results of cross-sectional and prospective studies of external eating style and body weight were more mixed 60 — 65perhaps because many adults who have a vulnerability to overeating highly palatable food Two palatable chap to control their Two palatable chap with dietary restraint Despite some evidence linking responsiveness to foods with higher intake and higher weight, both hyper- and hypo-responsiveness to food reward were observed in obese adults 67 — This apparent inconsistency was explained in terms of a tendency toward hyperactivity in the corticolimbic areas involved with food reward or food-seeking behavior in obese individuals, in conjunction with lower reward responses to ingestion resulting from their more frequent intake of palatable foods 4 This may lead to further consumption to compensate for the reward deficit A cyclical relation between hedonic responses to taste and obesity is likely, whereby individual differences predispose to overeating, and the resulting obese state further alters hedonic processing Food variety has been studied widely as a promoter of increased intake.
Providing a variety of foods varying in taste, texture, and appearance stimulates intake both within meals and across eating episodes in humans 71572 and laboratory animals 7 This tendency may have evolved to maximize the probability of adequate nutrient intake by stimulating renewed eating when a new food type became available, but behavior that was adaptive in conditions of food scarcity can confer a risk of overeating in an environment in which a varied, palatable, and energy-dense food supply is the norm.
The variety effect over a single meal has been attributed to sensory-specific satiety Two palatable chap Consumption of any 1 food ultimately leads to a decline in ratings of its pleasantness liking and the desire to eat it wanting relative to ratings of nonconsumed foods 74 — In the standard experimental paradigm, presentation of a new, palatable food often reinstates eating, even in conditions of satiation Even small differences in the sensory properties of foods can induce the variety effect 7879although effects are strongest when the foods differ substantially, e.
A number of studies examined the effect of increasing variety of foods on intake over days or weeks in humans. These studies showed that a high-variety vs. Similarly, the reverse, known as the monotony effect, is well documented Two palatable chap experimental and field studies, whereby repeated presentation of the same foods over several meals or days results in sharply declining palatability ratings and reduced food intake 83 — The phenomenon was studied in animals and Two palatable chap, with responses to foods measured in a variety of ways including neural activity 93salivation 94Two palatable chap motivated responses Habituation can also be observed in response to olfactory cues or food presentations of no nutritive value 92demonstrating the central role of sensory, rather than homeostatic, processes.
The long-term effects Two palatable chap dietary variety on body Two palatable chap have not been directly tested. One 7-d experimental study reported that dietary variety was associated with short-term weight change in lean but not obese men Observational studies showed associations between variety of foods in the diet and adiposity in free-living humans 96 — 98although this association is moderated by the macronutrient content of the varied food in the diet.
A similar study in a Hong Kong Chinese population 97 found that a variety of snack foods consumed over 1 wk was associated with greater adiposity, whereas a variety of grains and meats was associated with lower adiposity.
There was no association for fruits and vegetables. Correlational studies associated monotonous diets with weight loss in anorexia nervosa patients 99 and elderly adults However, these studies examined effects of the variety of Two palatable chap consumed rather than variety as an exposure, and do not necessarily demonstrate that access to variety affects weight; the results may be due to heavier people selecting differently, rather than varied options creating heavier people.
Animal studies often demonstrated that increasing dietary variety results in weight gain, although, as discussed above, in the majority of studies using cafeteria-style feeding, differences in the energy density and palatability of the varied vs.
Two studies comparing nutritionally balanced diets that either were monotonous or had varied flavors and textures found conflicting results. One showed an effect of variety on intake and weight in ratsbut the other showed no effectalthough it was suggested that Two palatable chap latter finding is due to the fact that many of the flavors used in the varied diet were less palatable than the standard form.
A review of internal and external moderators of the variety effect concluded that there was little evidence for individual differences Age is associated with earlier satiation and reduced sensitivity to food cues, and as people age they show a reduced variety effect 15but variety is still associated Two palatable chap increased intake among older adults. Obese individuals are less responsive to satiety processes and habituate more slowly to food stimuli —so they might be expected to be less Two palatable chap to the variety effect.
However, several studies manipulating the variety of food during 1 meal found no differences between obese and normal weight participants; both groups ate equivalently more when there was a greater variety of food available— Two studies have reported differences in the variety effect by body weight.
The reverse effect was seen in a study of overweight and normal-weight children, in which overweight children increased their energy intake more than lean children in response to variety At present, the balance of evidence suggests that the variety effect does not appear to differ consistently by body weight status.
Two Two palatable chap studies examined the effect of manipulating variety as part of a weight-loss intervention. The first of these compared limiting snack food variety with limiting snack frequency Hedonic ratings of the snack food and snack consumption declined more in the reduced variety condition, but the 2 groups lost similar amounts of weight.
The second examined the effect of limiting variety of energy-dense, nutrient-poor foods in an mo weight loss intervention Restricting variety was successful in reducing energy intake from this food group, but did not result in reduced energy intake overall or increased weight loss, leading the authors to suggest that restriction of variety may need to be extended to a wider range of food types Two palatable chap it is to contribute to weight loss.
Two palatable chap practice, dietary regimes that reduce variety are common both in therapeutic settings and among individuals who wish to lose weight independently.
Meal replacement diets such as very low calorie diets involve replacement of some or all meals with a single nutritionally balanced, calorie-controlled product, often a milkshake.
Very low calorie diets, which severely limit variety, often have relatively high ratings of acceptability, good adherence, and lower ratings of hunger than less restrictive diets — Some popular commercial diets, such as Two palatable chap high-protein, low-carbohydrate Atkins diet, eliminate large numbers of foods, and the reduced variety may be 1 of the mechanisms behind their short-term effectiveness Fad diets often encourage exclusive consumption of a single food of limited palatability e.
Although many of these monotonous diets are effective at producing weight loss in the short term 84—no studies used comparison conditions that make it possible to attribute the effects directly Two palatable chap variety because the diets are often portion-controlled and differ in macronutrient composition, energy density, and palatability.
There is solid evidence for a causal role of food palatability on increased short-term energy intake based on experimental studies in humans and animals. Providing laboratory animals with a palatable cafeteria diet has also been shown to result in weight gain, but attributing this to effects of palatability alone is not possible, because these diets are also more energy-dense and varied than a standard diet.
In humans, although it is highly plausible Two palatable chap the increasing palatability of the food supply has contributed to increasing weight in the population, studies have not been carried out that demonstrate unequivocally that personal exposure to highly palatable foods leads directly to weight gain.
Individual variation in responsiveness to food palatability can contribute to explaining weight variation.
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Food responsiveness varies from birth, and longitudinal studies showed that it is associated with weight gain in children 58 Epidemiologic data from adult studies are less conclusive. Imaging studies show that brain responses to palatable Two palatable chap distinguish obese from normal-weight adults, but hypothesized causal mechanisms based on the effects of overexposure to palatable foods in susceptible individuals were not tested in humans.
Experimental studies demonstrate a robust association between an increased variety of foods available and increased intake within a meal in a laboratory setting. Although there is limited systematic research into the effect of variety on longer-term intake or weight change, dietary variety was associated with weight gain, and dietary monotony with weight loss, in several correlational and short-term experimental studies.
There is little evidence of individual differences in responsiveness to variety, and obese and normal-weight individuals do not consistently differ in their susceptibility to sensory-specific satiety and the variety effect. The balance of evidence is consistent with the idea that exposure to a varied food supply will result in increased intake and weight gain in the long term, but this has not been conclusively demonstrated in any studies to date.
High Two palatable chap of variety and palatability are key features of modern diets, and this Two palatable chap unlikely to change in the near future. Similarities between responses Two palatable chap highly palatable food and addictive drugs in reward-related brain regions resulted in a debate over whether overeating could be considered a reflection of food addiction 30, Human brain studies show that mesolimbic dopamine pathways activated in response to palatable foods are the same as those activated in drug addiction — and can trigger withdrawal effects similar to those seen with opioid drugs Variety, Palatability, and Obesity1,2,3,4 .
Semmler C, Ashcroft J, van Jaarsveld CH, Carnell S, Wardle J. Development of overweight in. non-palatalized forms Table A.2 Table A.3 Table A.4 Table A.5 Table A.6 in texts with words entirely unaffected by the k-palatalization process (Chapter Two).
Potential intake level by the ruminant animal is considered one of the two Read full chapter.
Chapter. from book Eighteenth International...
The dilemma between functionality and palatability.