Effects of food unit size and energy density on intake in humans

Passive overconsumption? Limited evidence of compensation in meal size when consuming foods high in energy density: Two randomised crossover experiments

Research has drawn contradictory conclusions as to whether humans adjust meal size based on meal energy density (ED) or exhibit 'passive overconsumption'. Recent observational research has suggested that meal EDs greater than 1.7-2 kcal/g are compensated for through consumption of smaller meal sizes. We tested the relationship between ED and meal size by examining energy intake of meals at three levels of ED: low (∼1.0 kcal/g), medium (1.7-2.0 kcal/g) and high (>3.0 kcal/g). Two randomised, crossover experiments were conducted with adult participants. In experiment 1 (n = 34, 62% female, mean age 37.4 years), participants were served a lunch including a familiar low, medium or high ED dessert to eat ad libitum. In experiment 2 (n = 32, 66% female, mean age 36.4 years), participants were served a lunch meal manipulated to be low, medium or high ED to eat ad libitum. For experiment 2, later energy intake (post-meal energy intake) was also measured. In experiment 1, participants consumed a similar amount of energy from the low vs. medium ED food. The high ED food was associated with an increased intake of approximately 240 kcals compared to medium (p < 0.001, Cohen's d = 2.31) and low (p < 0.001, Cohen's d = 4.42) ED foods. In experiment 2, there were no significant differences in meal size (grams) between ED meals, resulting in a largely linear relationship between meal ED and energy intake across the three ED conditions ('passive overconsumption'). There were no differences in later energy intake between ED conditions. Contrary to recent suggestions, foods higher in ED were not associated with adjustments to meal size and were associated with increased energy intake across two experiments. Reformulation of foods high in ED may be an effective population level approach to reducing energy intake and obesity. Clinical trial registry number: NCT05744050; https://clinicaltrials.gov/ct2/show/NCT05744050.

Unit size influences ad libitum intake in a snacking context via eating rate

Geometric and textural properties of food, like unit size, have previously been shown to influence energy intake. While mechanism(s) driving this effect are unclear, unit size may relate to intake by affecting eating microstructure (e.g., eating rate, bite size). In a randomized crossover study, we investigated relationships between unit size, eating microstructure, and intake. Adults (n = 75, 75% women) consumed an ad libitum snack three times in our laboratory. This snack was a 70-g portion (∼2.5 servings) of one of three sizes of pretzel (small, medium, large). Intake was measured in grams by difference in weight before and after the snack. Each session was video recorded to measure eating microstructure; snack duration (min) and number of bites were annotated and used to calculate mean eating rate (g/min) and mean bite size (g/bite). Results revealed unit size influenced intake (grams and kcal; both p's ≤ 0.001), such that participants consumed 31% and 22% more of the large pretzels (16.9 ± 2.3 g) compared to the small (12.9 ± 2.3 g) and medium sizes (13.8 ± 2.3 g), respectively. Unit size also influenced eating rate and bite size (both p's < 0.001); the largest pretzel size yielded the fastest eating rate and largest mean bite size. Further analysis revealed that after accounting for eating microstructure, the effects of unit size on intake were no longer significant, suggesting eating microstructure was driving these effects. Together, these findings indicate that unit size influences intake by affecting eating microstructure and that food properties like unit size can be leveraged to moderate snack intake.

Impact of energy density on energy intake in children and adults: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

The energy density (ED) of a diet can be leveraged to prevent weight gain or treat overweight and obesity. By lowering the ED of the diet, energy intake can be reduced while maintaining portion size. However, a reliable meta-analysis of data from randomized controlled trials (RCTs) is missing. Therefore, this meta-analysis synthesized the evidence of ED manipulation on energy intake in RCTs.

METHODS

The systematic literature search of multiple databases according to PRISMA criteria considered RCTs investigating the objectively measured energy intake from meals with different ED (lower ED (median 1.1 kcal/g) versus higher ED (median 1.5 kcal/g)) under controlled conditions. Subgroup analyses for age (children versus adults), meal type (preload versus entrée design), and intervention length (1 meal versus > 1 meal) were performed to achieve the most homogeneous result.

RESULTS

The meta-analysis of 38 included studies demonstrated that lowering ED considerably reduced energy intake - 223 kcal (95% CI: - 259.7, - 186.0) in comparison to the higher ED interventions. As heterogeneity was high among studies, subgroup analyses were conducted. Heterogeneity decreased in subgroup analyses for age and meal type combined, strengthening the results. An extended analysis showed a positive linear relationship between ED and energy intake. Dietary ED did not affect the amount of food intake.

CONCLUSION

Manipulating ED substantially affects energy intake whereas food intake remains constant. Thus, this approach can be regarded as a powerful tool for weight management through nutrition therapy. Registration on 08/08/2021: CRD42021266653.

Calorie reformulation: a systematic review and meta-analysis examining the effect of manipulating food energy density on daily energy intake

BACKGROUND

Dietary energy density is thought to be a contributor to obesity, but the extent to which different magnitudes and types of reductions to food energy density decreases daily energy intake is unclear. The primary objective was to systematically review and meta-analyse experimental studies that have examined the effect that manipulating energy density of food has on total daily energy intake. Secondary objectives were to examine moderators of the effect that altering energy density has on daily energy intake and effects on body weight.

METHODS

A systematic review and multi-level meta-analysis of studies on human participants that used an experimental design to manipulate the energy density of foods served and measured energy intake for a minimum of 1 day.

RESULTS

Thirty-one eligible studies sampling both children (n = 4) and adults (n = 27) contributed 90 effects comparing the effect of higher vs. lower energy density of served food on daily energy intake to the primary meta-analysis. Lower energy density of food was associated with a large decrease in daily energy intake (SMD = - 1.002 [95% CI: - 0.745 to - 1.266]). Findings were consistent across studies that did vs. did not manipulate macronutrient content to vary energy density. The relation between decreasing energy density and daily energy intake tended to be strong and linear, whereby compensation for decreases to energy density of foods (i.e. by eating more at other meals) was minimal. Meta-analysis of (n = 5) studies indicated that serving lower energy dense food tended to be associated with greater weight loss than serving higher energy dense food, but this difference was not significant (- 0.7 kg difference in weight change, 95% CIs: - 1.34, 0.04).

CONCLUSIONS

Decreasing the energy density of food can substantially reduce daily energy intake and may therefore be an effective public health approach to reducing population level energy intake.

TRIAL REGISTRATION

Registered on PROSPERO ( CRD42020223973 ).

Can front-of-pack labels influence portion size judgements for unhealthy foods?

OBJECTIVE

By clearly conveying the healthiness of a food, front-of-pack (FOP) labels have the potential to influence the portion size considered appropriate for consumption. The present study examined the how the Daily Intake Guide (DIG), Multiple Traffic Lights (MTL) and Health Star Rating (HSR) FOP labels affect judgements of appropriate portion sizes of unhealthy foods compared with when no FOP label is present.

DESIGN

Respondents viewed mock packages of unhealthy variations of pizzas, cookies, yoghurts and cornflakes featuring the DIG, MTL, HSR or no FOP label, and indicated the portion size they believed should be eaten of each food on a single occasion.

SETTING

The survey was completed on the respondent's personal computer.

SUBJECTS

A total of 1505 Australian adults provided 4166 ratings across 192 mock packages relating to four product categories: pizza, yoghurt, cornflakes and cookies.

RESULTS

Compared with no FOP label, the HSR resulted in a small but significant reduction in the portion size selected as appropriate for consumption of pizzas and cornflakes (P<0·05). The MTL resulted in smaller portions of cornflakes being selected compared with no FOP label (P<0·05).

CONCLUSIONS

Respondents perceived smaller portion sizes as appropriate for some, but not all, of the foods tested when FOP labels with more interpretative formats (HSR, MTL) appeared on-pack compared with no FOP label. No effect was found for the less interpretive FOP label (the DIG). Interpretive FOP labels may have the potential to influence portion size judgements, albeit at modest levels.

The Effect of Food Unit Sizes and Meal Serving Occasions on Eating Behaviour Characteristics: Within Person Randomised Crossover Studies on Healthy Women

Manipulating food properties and serving environment during a meal can significantly change food intake at group level. However, the evaluation of the usefulness of such manipulations requires an understanding of individual behavioural changes. Three studies were conducted to explore the effect of unit size and meal occasion on eating behaviour characteristics (food intake, meal duration, number of bites and chews). All studies used a randomised crossover design, with a one-week wash-out period, starting with a familiarisation meal, with the participation of healthy, normal weight females between the ages of 18–35 years. In Study 1 (n = 19) three cube sizes (0.5, 1.0 and 1.5 cm³) of vegetable hash and chicken were compared. In Study 2 (n = 18) mashed potatoes and mincemeat were compared to whole potatoes and meatballs. In Study 3 (n = 29) meals served at lunch time (11:00–13:00) were compared to identical meals served at dinner time (17:00–19:00). The largest food unit size lead to significantly increased meal duration in Study 2 (mean difference 0.9 min, 95% confidence interval (CI) 0.0–1.8), but not in Study 1 (mean difference 1 min, 95% CI 0.1–2.0). There was a significant increase in number of chews in the large unit size condition of both Study 1 (mean difference 88, 95% CI 12–158) and Study 2 (mean difference 95, 95% CI 12–179). Different serving occasions did not significantly change any of the eating behaviours measured. Except for number of bites in Study 2 (R² = 0.60), most individuals maintained their eating behaviour relative to the group across unit sizes and serving occasions conditions (R² > 0.75), which suggests single meal testing can provide information about the behavioural characteristics of individual eating styles under different conditions.

The effect of preload/meal energy density on energy intake in a subsequent meal: A systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the effects of preload/meal energy density on energy intake in a subsequent meal(s).

METHODS

Multiple databases were searched for studies published through December 2016 on the effects of preload/meal energy density on energy intake in a subsequent meal(s). We extracted information on mean energy intake in a subsequent meal(s) and on variables that could contribute to between-subject heterogeneity.

RESULTS

Forty and Thirty nine eligible studies were identified for our systematic review and meta-analysis, respectively. The meta-analysis showed that preload/meal energy density did not affect energy intake in a subsequent meal(s) (95% CI:-21.21, 21.29). As heterogeneity was remarkable among studies, we stratified the studies by intervention type into "meal" or "preload" classifications. In the "preload" subgroup, studies used either fixed energy or fixed weight preloads. The results reveal that in comparison to a high energy-dense (HED) preload, consuming a low energy-dense (LED) preload with same weight resulted in higher energy intake in a subsequent meal (95% CI: 9.72, 56.19). On the other hand, decreased energy intake was observed after consuming an LED preload compared to after consumption of an HED preload with same energy content (95% CI: -138.71, -57.33). In the "meal" subgroup, studies were categorized by different subsequent meal (i.e., "afternoon or evening", "lunch" and "dinner or post-dinner"). Meta-analysis showed that an LED meal resulted in more energy intake only in afternoon or evening meals (95% CI: 14.82, 31.22).

CONCLUSION

In summary, the current analysis revealed that we can restrict the energy intake by consuming an LED preload. Moreover, consuming an LED preload could favorably affect preload+meal energy intake.

Depicted serving size: cereal packaging pictures exaggerate serving sizes and promote overserving

Background

Extensive work has focused on the effects of nutrition label information on consumer behavior on the one hand, and on the effects of packaging graphics on the other hand. However, little work has examined how serving suggestion depictions - graphics relating to serving size - influence the quantity consumers serve themselves. The current work examines the prevalence of exaggerated serving size depictions on product packaging (study 1) and its effects on food serving in the context of cereal (study 2).

Methods

Study 1 was an observational field survey of cereal packaging. Study 2 was a mixed experimental cross-sectional design conducted at a U.S. university, with 51 student participants. Study 1 coded 158 US breakfast cereals and compared the serving sizes depicted on the front of the box with the suggested serving size stated on the nutrition facts panel. Study 2 measured the amount of cereal poured from exaggerated or accurate serving size depictions. Study 1 compared average servings via t-tests. Study 2 used a mixed model with cereal type as the repeated measure and a compound symmetry covariance matrix.

Results

Study 1 demonstrated that portion size depictions on the front of 158 cereal boxes were 64.7% larger (221 vs. 134 calories) than the recommended portions on nutrition facts panels of those cereals. Study 2 showed that boxes that depicted exaggerated serving sizes led people to pour 17.8% more cereal compared to pouring from modified boxes that depicted a single-size portion of cereal matching suggested serving size. This was 42% over the suggested serving size.

Conclusions

Biases in depicted serving size depicted on cereal packaging are prevalent in the marketplace. Such biases may lead to overserving, which may consequently lead to overeating. Companies should depict the recommended serving sizes, or otherwise indicate that the depicted portion represents an exaggerated serving size.

The efficacy of nudge theory strategies in influencing adult dietary behaviour: a systematic review and meta-analysis

Background

Obesity has become a world-wide epidemic and is spreading to countries with emerging economies. Previously tested interventions are often too costly to maintain in the long term. This leaves a need for improved strategies for management of the epidemic. Nudge Theory presents a new collection of methods, deemed “nudges”, which have the potential for low-cost and broad application to guide healthier lifestyle choices without the need for restrictive regulation. There has not yet been a large-scale examination of the effectiveness of nudges, despite several policy making bodies now considering their use.

Methods

To address this gap in knowledge, an adapted systematic review methodology was used to collect and consolidate results from current Nudge papers and to determine whether Nudge strategies are successful in changing adults’ dietary choices for healthier ones.

Results

It was found that nudges resulted in an average 15.3 % increase in healthier dietary or nutritional choices, as measured by a change in frequency of healthy choices or a change in overall caloric consumption. All of the included studies were from wealthy nations, with a particular emphasis on the United States with 31 of 42 included experiments.

Conclusions

This analysis demonstrates Nudge holds promise as a public health strategy to combat obesity. More research is needed in varied settings, however, and future studies should aim to replicate previous results in more geographically and socioeconomically diverse countries.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3272-x) contains supplementary material, which is available to authorized users.

Portion size: what we know and what we need to know

There is increasing evidence that the portion sizes of many foods have increased and in a laboratory at least this increases the amount eaten. The conclusions are, however, limited by the complexity of the phenomenon. There is a need to consider meals freely chosen over a prolonged period when a range of foods of different energy densities are available. A range of factors will influence the size of the portion size chosen: amongst others packaging, labeling, advertising, and the unit size rather than portion size of the food item. The way portion size interacts with the multitude of factors that determine food intake needs to be established. In particular, the role of portion size on energy intake should be examined as many confounding variables exist and we must be clear that it is portion size that is the major problem. If the approach is to make a practical contribution, then methods of changing portion sizes will need to be developed. This may prove to be a problem in a free market, as it is to be expected that customers will resist the introduction of smaller portion sizes, given that value for money is an important motivator.

Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco

BACKGROUND

Overeating and harmful alcohol and tobacco use have been linked to the aetiology of various non-communicable diseases, which are among the leading global causes of morbidity and premature mortality. As people are repeatedly exposed to varying sizes and shapes of food, alcohol and tobacco products in environments such as shops, restaurants, bars and homes, this has stimulated public health policy interest in product size and shape as potential targets for intervention.

OBJECTIVES

1) To assess the effects of interventions involving exposure to different sizes or sets of physical dimensions of a portion, package, individual unit or item of tableware on unregulated selection or consumption of food, alcohol or tobacco products in adults and children.2) To assess the extent to which these effects may be modified by study, intervention and participant characteristics.

SEARCH METHODS

We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, eight other published or grey literature databases, trial registries and key websites up to November 2012, followed by citation searches and contacts with study authors. This original search identified eligible studies published up to July 2013, which are fully incorporated into the review. We conducted an updated search up to 30 January 2015 but further eligible studies are not yet fully incorporated due to their minimal potential to change the conclusions.

SELECTION CRITERIA

Randomised controlled trials with between-subjects (parallel-group) or within-subjects (cross-over) designs, conducted in laboratory or field settings, in adults or children. Eligible studies compared at least two groups of participants, each exposed to a different size or shape of a portion of a food (including non-alcoholic beverages), alcohol or tobacco product, its package or individual unit size, or of an item of tableware used to consume it, and included a measure of unregulated selection or consumption of food, alcohol or tobacco.

DATA COLLECTION AND ANALYSIS

We applied standard Cochrane methods to select eligible studies for inclusion and to collect data and assess risk of bias. We calculated study-level effect sizes as standardised mean differences (SMDs) between comparison groups, measured as quantities selected or consumed. We combined these results using random-effects meta-analysis models to estimate summary effect sizes (SMDs with 95% confidence intervals (CIs)) for each outcome for size and shape comparisons. We rated the overall quality of evidence using the GRADE system. Finally, we used meta-regression analysis to investigate statistical associations between summary effect sizes and variant study, intervention or participant characteristics.

MAIN RESULTS

The current version of this review includes 72 studies, published between 1978 and July 2013, assessed as being at overall unclear or high risk of bias with respect to selection and consumption outcomes. Ninety-six per cent of included studies (69/72) manipulated food products and 4% (3/72) manipulated cigarettes. No included studies manipulated alcohol products. Forty-nine per cent (35/72) manipulated portion size, 14% (10/72) package size and 21% (15/72) tableware size or shape. More studies investigated effects among adults (76% (55/72)) than children and all studies were conducted in high-income countries - predominantly in the USA (81% (58/72)). Sources of funding were reported for the majority of studies, with no evidence of funding by agencies with possible commercial interests in their results.A meta-analysis of 86 independent comparisons from 58 studies (6603 participants) found a small to moderate effect of portion, package, individual unit or tableware size on consumption of food (SMD 0.38, 95% CI 0.29 to 0.46), providing moderate quality evidence that exposure to larger sizes increased quantities of food consumed among children (SMD 0.21, 95% CI 0.10 to 0.31) and adults (SMD 0.46, 95% CI 0.40 to 0.52). The size of this effect suggests that, if sustained reductions in exposure to larger-sized food portions, packages and tableware could be achieved across the whole diet, this could reduce average daily energy consumed from food by between 144 and 228 kcal (8.5% to 13.5% from a baseline of 1689 kcal) among UK children and adults. A meta-analysis of six independent comparisons from three studies (108 participants) found low quality evidence for no difference in the effect of cigarette length on consumption (SMD 0.25, 95% CI -0.14 to 0.65).One included study (50 participants) estimated a large effect on consumption of exposure to differently shaped tableware (SMD 1.17, 95% CI 0.57 to 1.78), rated as very low quality evidence that exposure to shorter, wider bottles (versus taller, narrower bottles) increased quantities of water consumed by young adult participants.A meta-analysis of 13 independent comparisons from 10 studies (1164 participants) found a small to moderate effect of portion or tableware size on selection of food (SMD 0.42, 95% CI 0.24 to 0.59), rated as moderate quality evidence that exposure to larger sizes increased the quantities of food people selected for subsequent consumption. This effect was present among adults (SMD 0.55, 95% CI 0.35 to 0.75) but not children (SMD 0.14, 95% CI -0.06 to 0.34).In addition, a meta-analysis of three independent comparisons from three studies (232 participants) found a very large effect of exposure to differently shaped tableware on selection of non-alcoholic beverages (SMD 1.47, 95% CI 0.52 to 2.43), rated as low quality evidence that exposure to shorter, wider (versus taller, narrower) glasses or bottles increased the quantities selected for subsequent consumption among adults (SMD 2.31, 95% CI 1.79 to 2.83) and children (SMD 1.03, 95% CI 0.41 to 1.65).

AUTHORS' CONCLUSIONS

This review found that people consistently consume more food and drink when offered larger-sized portions, packages or tableware than when offered smaller-sized versions. This suggests that policies and practices that successfully reduce the size, availability and appeal of larger-sized portions, packages, individual units and tableware can contribute to meaningful reductions in the quantities of food (including non-alcoholic beverages) people select and consume in the immediate and short term. However, it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range. We are unable to highlight clear implications for tobacco or alcohol policy due to identified gaps in the current evidence base.

Weighing the Evidence of Common Beliefs in Obesity Research

Obesity is a topic on which many views are strongly held in the absence of scientific evidence to support those views, and some views are strongly held despite evidence to contradict those views. We refer to the former as "presumptions" and the latter as "myths." Here, we present nine myths and 10 presumptions surrounding the effects of rapid weight loss; setting realistic goals in weight loss therapy; stage of change or readiness to lose weight; physical education classes; breastfeeding; daily self-weighing; genetic contribution to obesity; the "Freshman 15"; food deserts; regularly eating (versus skipping) breakfast; eating close to bedtime; eating more fruits and vegetables; weight cycling (i.e., yo-yo dieting); snacking; built environment; reducing screen time in childhood obesity; portion size; participation in family mealtime; and drinking water as a means of weight loss. For each of these, we describe the belief and present evidence that the belief is widely held or stated, reasons to support the conjecture that the belief might be true, evidence to directly support or refute the belief, and findings from randomized controlled trials, if available. We conclude with a discussion of the implications of these determinations, conjecture on why so many myths and presumptions exist, and suggestions for limiting the spread of these and other unsubstantiated beliefs about the obesity domain.

Mechanisms of the portion size effect. What is known and where do we go from here?

Childhood obesity is a persistent problem worldwide, and of particular concern in the United States. Clarifying the role of the food environment in promoting overeating is an important step toward reducing the prevalence of obesity. One potential contributor to the obesity epidemic is the increased portion sizes of foods commonly served. Portion sizes of foods served both at home and away from home have dramatically increased over the past 40 years. Consistently, short-term studies have demonstrated that increasing portion size leads to increased food intake in adults and children, a phenomenon known as the portion size effect. However, the mechanisms underlying this effect are poorly understood. Understanding these mechanisms could assist in clarifying the relationship between portion size and weight status and help inform the development of effective obesity interventions. First, we review the role of visual cues, such as plate size, unit, and utensil size as a potential moderator of the portion size effect. In addition, we discuss meal microstructure components including bite size, rate, and frequency, as these may be altered in response to different portion sizes. We also review theories that implicate post-ingestive, flavor-nutrient learning as a key moderator of the portion size effect. Furthermore, we present preliminary data from an ongoing study that is applying neuroimaging to better understand these mechanisms and identify modifiable child characteristics that could be targeted in obesity interventions. Our tentative findings suggest that individual differences in cognitive (e.g. loss of control eating) and neural responses to food cues may be critical in understanding the mechanisms of the portion size effect. To advance this research area, studies that integrate measures of individual subject-level differences with assessment of food-related characteristics are needed.

Portion size and obesity

Portion size is a key environmental driver of energy intake, and larger-than-appropriate portion sizes could increase the risk of weight gain. Multiple acute, well-controlled laboratory studies, supported by data from free-living settings, demonstrated that portion size has a powerful and proportionate effect on the amount of food consumed. Of particular importance is that bouts of overeating associated with large portions are sustained and not followed by a compensatory reduction in energy intake. The positive effect of portion size on energy intake was demonstrated for different types of foods and beverages, and is particularly pronounced with energy-dense foods. The predisposition to overeat in response to large portions is pervasive and occurs regardless of demographic characteristics, such as socioeconomic status, age, body mass index, and sex. Secular trends toward greater availability of large portions, coupled with value-size pricing, effectively distorted consumption norms and perceptions of what is an appropriate amount to eat. Nevertheless, although a direct causal link between portion size and obesity remains to be established, advice to moderate portion sizes, especially of energy-dense foods, is presently the cornerstone of most weight management advice. Although many strategies have been proposed to counteract the deleterious effects of portion size, there are few data indicating which are likely to be acceptable in the medium- to long term. Further research is urgently needed to establish what types of interventions targeted at portion size are likely to be effective, in what settings, and among which target groups.

Energy density, energy intake, and body weight regulation in adults

The role of dietary energy density (ED) in the regulation of energy intake (EI) is controversial. Methodologically, there is also debate about whether beverages should be included in dietary ED calculations. To address these issues, studies examining the effects of ED on EI or body weight in nonelderly adults were reviewed. Different approaches to calculating dietary ED do not appear to alter the direction of reported relations between ED and body weight. Evidence that lowering dietary ED reduces EI in short-term studies is convincing, but there are currently insufficient data to determine long-term effectiveness for weight loss. The review also identified key barriers to progress in understanding the role of ED in energy regulation, in particular the absence of a standard definition of ED, and the lack of data from multiple long-term clinical trials examining the effectiveness of low-ED diet recommendations for preventing both primary weight gain and weight regain in nonobese individuals. Long-term clinical trials designed to examine the impact of dietary ED on energy regulation, and including multiple ED calculation methods within the same study, are still needed to determine the importance of ED in the regulation of EI and body weight.

Weight status moderates the relationship between package size and food intake

Single-serving packages (SSPs) may assist people in reducing consumption. Because overweight/obese individuals and individuals practicing dietary restraint may be more responsive to external food cues regarding an amount of food to consume, we examined whether weight and restraint status influence the relationship between package size and consumption. It was hypothesized that SSPs would reduce intake in overweight/obese individuals and individuals practicing dietary restraint compared with standard packages (STPs). Using a 2×2×2 (unrestrained/restrained×normal weight/overweight×SSP/STP) between-subjects design, 64 participants (aged 23.7±3.3 years; 81.3% white; 46.9% female), from June to October 2011, were randomly assigned to receive 20 oz pretzels packaged in SSPs or STPs, and were instructed to eat the pretzels ad libitum for 4 days. Each condition in the design contained eight participants. Total grams consumed was determined by subtracting postconsumption from preconsumption weight of packages provided. Using an analysis of variance for total grams of pretzels consumed, there was a significant interaction (P=0.01) between package size and weight status. Overweight/obese participants in the SSP condition ate fewer grams of pretzels than overweight/obese participants in the STP condition (107.0±101.9 g vs 204.4±144.9; P<0.05). No effect of restraint was found on consumption. For overweight/obese individuals, fewer pretzels were consumed when packaged in SSPs compared with STPs. Thus, replacing STPs with SSPs may assist with reducing consumption in some overweight/obese individuals.

Does food marketing need to make us fat? A review and solutions

Food marketing is often singled out as the leading cause of the obesity epidemic. The present review examines current food marketing practices to determine how exactly they may be influencing food intake, and how food marketers could meet their business objectives while helping people eat healthier. Particular attention is paid to the insights provided by recently published studies in the areas of marketing and consumer research, and those insights are integrated with findings from studies in nutrition and related disciplines. The review begins with an examination of the multiple ways in which 1) food pricing strategies and 2) marketing communication (including branding and food claims) bias food consumption. It then describes the effects of newer and less conspicuous marketing actions, focusing on 3) packaging (including the effects of package design and package-based claims) and 4) the eating environment (including the availability, salience, and convenience of food). Throughout, this review underscores the promising opportunities that food manufacturers and retailers have to make profitable "win-win" adjustments to help consumers eat better.

Distinct foods with smaller unit would be an effective approach to achieve sustainable weight loss

We studied the effects of food type and food unit size on food intake and satiety using fried rice mixed with Kimchi in healthy Korean young women (n=31). Amorphous fried rice (1st week), distinct large fried rice balls (100 g/unit, 2nd week) and distinct small fried rice balls (20 g/unit, 3rd week) were served in the same content and volume (500 g). Subjects ate significantly (p<.001) less distinct large fried rice balls (243.5 g) compared to amorphous fried rice (317.2 g). Despite consuming more amorphous fried rice, subjects did not feel significantly fuller after eating amorphous fried rice compared to distinct large fried rice balls. When distinct fried rice balls were served as smaller unit, subjects ate significantly less them (small unit; 190.6 g vs. large unit; 243.5 g, p<.01). Although subjects ate more distinct fried rice balls provided as large unit, they rated similar satiety and hunger levels for distinct small and distinct large fried rice balls. In conclusion, we propose that distinct foods with smaller unit would be an effective approach to achieve sustainable weight loss.

The 100-calorie semi-solution: sub-packaging most reduces intake among the heaviest

This study addresses two questions about sub-packaging: (i) Do 100-calorie packages reduce the calorie intake of overweight individuals differently than normal-weight individuals? (ii) Do they enable individuals to accurately track intake? Thirty-seven undergraduates were randomly given either four 100-calorie packages of crackers or one 400-calorie package of crackers to eat while watching television. The average participant ate 25.2% (75.1 calories) less when given four 100-calorie packages of crackers than when given one 400-calorie package (P = 0.006). In addition, much of this influence was driven by overweight participants whose intake decreased by 54.1%. However, all of the participants underestimated their consumption by 60% or more, indicating that sub-packaging does not appear to increase one's accuracy in estimating how much is consumed. Smaller sized sub-packaging most greatly benefits those who are overweight, yet it does so without making people more aware of how much they have eaten.

Appetitive and Dietary Effects of Consuming an Energy-Dense Food (Peanuts) with or between Meals by Snackers and Nonsnackers

Background. Energy-dense foods are inconsistently implicated in elevated energy intake (EI). This may stem from other food properties and/or differences in dietary incorporation, that is, as snacks or with meals. Objective. Assess intake pattern and food properties on acute appetitive ratings (AR) and EI. Design. 201 normal and overweight adults consuming a standard lunch. Test loads of 1255.2 kJ (300 kcal) were added to the lunch or provided as snack. Loads (peanuts, snack mix, and snack mix with peanuts) were energy, macronutrient, and volumetrically matched with a lunch portion as control. Participants completed meal and snack sessions of their randomly assigned load. Results. No differences were observed in daily EI or AR for meal versus snack or treatment versus control. Consumption of peanuts as a snack tended to strengthen dietary compensation compared to peanuts or other loads with a meal. Conclusions. Inclusion of an energy-dense food as a snack or meal component had comparable influence on AR and EI. Peanuts tended to elicit stronger dietary compensation when consumed as a snack versus with a meal. If substantiated, this latter observation suggests that properties other than those controlled here (energy, macronutrient content, and volume) modify AR and EI.

Lowering the energy density of parboiled rice by adding water-rich vegetables can decrease total energy intake in a parboiled rice-based diet without reducing satiety on healthy women

In this study, we examined whether the energy density of parboiled rice could influence the total energy intake and satiety of a parboiled rice-based diet by using vegetable. Healthy women (n=30) ate similar amounts of two types of parboiled rice in which energy intake from parboiled vegetable rice (177.7±4.0kcal) was significantly (p<0.001) lower than that from parboiled normal rice (301.5±9.3kcal) due to differences in energy density (parboiled normal rice: 1.42kcal/g, parboiled vegetable rice: 0.86kcal/g). Despite lower energy intake, the subjects consumed significantly less parboiled rice and side dishes at dinner after they consumed parboiled vegetable rice diet for lunch compared with parboiled normal rice diet. The subjects also reported higher levels of fullness and lower levels of hunger after eating the parboiled vegetable rice diet compared to the parboiled normal rice diet. At 4h after lunch, the average hunger rating of parboiled vegetable rice diet (22.1±2.43mm) was significantly (p<0.001) lower than that of parboiled normal rice diet (56.2±2.41mm). In conclusion, these results indicate that consuming low energy dense parboiled rice by eating parboiled vegetable rice in place of parboiled normal rice may be a useful strategy for weight loss and weight management since it allows individuals to consume fewer calories without reducing satiety.

Hunger and thirst: issues in measurement and prediction of eating and drinking

Associations between hunger and eating and between thirst and drinking are generally weak. This stems, in part, from limitations in the measurement of these sensations which generally rely on temporal, motivational, metabolic and/or self-reported descriptive indices. Each is critically reviewed. Also problematic is the fact that the deterministic depletion-repletion concept of ingestive behavior fails to account for influences of a multitude of contravening cognitive, social, sensory and logistical factors. Although hunger and thirst serve some parallel purposes, sharp distinctions are also present with health implications. Of particular note are the observations that thirst ratings are higher and more stable over the day compared to hunger and thirst may be more motivating to drink than hunger is to eat. Coupling these observations with evidence that beverages have limited satiety value, they pose particular challenges and opportunities. Beverages can facilitate the delivery of nutrients to those desiring or requiring them, but also to those where they are not desired or required. The benefits and risks are a function of their use rather than their inherent properties.

Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association

High intakes of dietary sugars in the setting of a worldwide pandemic of obesity and cardiovascular disease have heightened concerns about the adverse effects of excessive consumption of sugars. In 2001 to 2004, the usual intake of added sugars for Americans was 22.2 teaspoons per day (355 calories per day). Between 1970 and 2005, average annual availability of sugars/added sugars increased by 19%, which added 76 calories to Americans' average daily energy intake. Soft drinks and other sugar-sweetened beverages are the primary source of added sugars in Americans' diets. Excessive consumption of sugars has been linked with several metabolic abnormalities and adverse health conditions, as well as shortfalls of essential nutrients. Although trial data are limited, evidence from observational studies indicates that a higher intake of soft drinks is associated with greater energy intake, higher body weight, and lower intake of essential nutrients. National survey data also indicate that excessive consumption of added sugars is contributing to overconsumption of discretionary calories by Americans. On the basis of the 2005 US Dietary Guidelines, intake of added sugars greatly exceeds discretionary calorie allowances, regardless of energy needs. In view of these considerations, the American Heart Association recommends reductions in the intake of added sugars. A prudent upper limit of intake is half of the discretionary calorie allowance, which for most American women is no more than 100 calories per day and for most American men is no more than 150 calories per day from added sugars.

Influência de alimentos líquidos e sólidos no controle do apetite

Este trabalho discute o papel dos alimentos líquidos e sólidos na ingestão alimentar, fundamentando-se em uma revisão crítica sobre o assunto. Utilizaram-se os principais bancos de dados nacionais e internacionais em saúde, entre eles, Medline/PubMed, Web of Science, Lilacs, SciELO. A busca bibliográfica compreendeu o período de 1980 a 2008. Os resultados atuais das pesquisas indicam que o estado físico do alimento pode influenciar o consumo alimentar, tanto a curto quanto a longo prazo, e que os alimentos líquidos exercem um menor poder sacietógeno, em comparação aos sólidos. Os possíveis mecanismos envolvidos nesse fraco controle do apetite pelos líquidos são: falta de mastigação, fase cefálica da ingestão menos pronunciada, esvaziamento gástrico mais rápido e fatores cognitivos. Conclui-se que o uso de alimentos líquidos, em especial bebidas energéticas, deve ser moderado tanto na prevenção como no tratamento da obesidade.

Do calorie-controlled portion sizes of snacks reduce energy intake?

In a cross-over study, participants (n=59) were randomly assigned to receive either 100 kcal packs or standard size packages of snacks for 1 week. After a minimum of a 1-week washout period, participants received the other form of the snack for 1 week. Snack consumption was recorded by participants in a diary. Participants consumed an average of 186.9 fewer grams of snacks per week when receiving 100 kcal snack packs compared to standard size packages of snacks. Post hoc comparisons revealed the effect of package size depended on both randomization order and study week. Total grams of snacks consumed in week 1 differed significantly between the two randomized groups. In week 2, however, grams of snacks did not differ significantly between the two groups. This interaction was primarily due to a significantly lower consumption of snacks from standard size packages in the week following the portion-controlled packages. The results suggest that portion-controlled packaging reduce total intake from the provided snacks. Further, initial exposure to portion-controlled packages might have increased awareness of portion size such that less was consumed when larger packages were available.

Relationships between human thirst, hunger, drinking, and feeding

There is a widely held view that hunger prompts feeding to ensure energy needs are met, while thirst cues drinking to address hydration requirements. However, recent changes in the nature of the food supply and eating patterns have raised questions about the functionality of these relationships with respect to maintaining energy balance. The increasing consumption of energy-yielding beverages and foods with diluted energy density, through the use of ingredients such as high-intensity sweeteners and fat replacers, poses new challenges to presumed homeostatic energy regulatory mechanisms. This review draws on findings from a recent observational study and other published evidence to explore whether shifts of food composition and use patterns may be disrupting relationships between thirst, hunger, drinking, and eating, resulting in positive energy balance (e.g., drinking low satiety, energy-yielding beverages in response to hunger). The observational study entailed collecting hourly appetitive ratings and dietary recalls from 50 adults for seven consecutive days. These data reveal a clear bimodal daily hunger pattern, whereas thirst is stronger and more stable throughout the day. Further, approximately 75% of fluid intake occurs peri-prandially, with the majority derived from energy-yielding beverages. While there is published evidence that drinking is responsive to feeding, support for the view that drinking is the more tightly regulated behavior is stronger. Our data indicates that, due to a number of plausible factors, neither absolute values nor changes of hunger or thirst are strong predictors of energy intake. However, it is proposed that stable, high thirst facilitates drinking, and with the increased availability and use of energy-yielding beverages that have low satiety properties, can promote positive energy balance. There are marked individual differences in mean daily hunger and thirst ratings with unknown implications for energy balance.

Lack of energy compensation over 4 days when white button mushrooms are substituted for beef

Increasing intake of low energy density (ED) foods in place of high ED foods has been proposed as a strategy for preventing or treating obesity. This study investigated how substituting mushrooms for beef in a test lunch affected energy intake, fat intake, palatability, appetite, satiation and satiety in normal weight, overweight and obese adults. Each subject consumed a total of eight test lunches in our lab over two consecutive weeks. The order of presentation of four consecutive meat lunches and four consecutive mushroom lunches was randomized. Energy content of meat and mushroom lunches varied (783 kcal versus 339 kcal), while volume was held constant. Energy intakes were significantly higher during meat lunches than mushroom lunches (730+/-7.9 kcal versus 310+/-5.8 kcal). Subjects exhibited only partial compensation (11.4+/-12.0%) for this difference over 4 days. Total daily energy intake and fat intake were significantly greater in the meat condition than in the mushroom condition, while ratings of palatability, appetite, satiation and satiety did not differ significantly. These results suggest that substituting low ED foods for high ED foods in otherwise similar recipes can be an effective method for reducing daily energy and fat intake.

Package unit size and amount of food: do both influence intake?

OBJECTIVE

Large portions increase intake and are hypothesized to contribute to the obesity epidemic. However, it is unclear if portion size affects intake through changes in the unit size of available food or the overall amount of food available for consumption. Thus, this study examined the independent effects of package unit size and amount of food on intake. It was hypothesized that both variables would influence intake.

RESEARCH METHODS AND PROCEDURES

Non-obese (BMI <30 kg/m(2)), non-smoking, unrestrained, college-aged men (n = 12) and women (n = 16) who regularly consumed (>or=3 times/wk) snack foods were randomly assigned to one of four groups crossing package unit size (small vs. large) and amount of food (small vs. large). Participants were given a box with 4 snack foods (potato chips, cheese crackers, cookies, and candy) packaged according to their assigned group to take home and eat over 3 days. Dependent variables were energy and gram intake of provided snack foods.

RESULTS

An effect of amount of food was found (p < 0.01). A 100% increase in the amount of food provided produced an 81% increase in energy consumed from the snack foods [small amount, 21,037.6 +/- 10,852 kJ (5,028 +/- 2,596 kcal) vs. large amount, 11,640.7 +/- 4,914.1 kJ (2,782 +/- 1,174 kcal)]. No effect of package unit size was found.

DISCUSSION

These results suggest that the amount of food available to eat strongly influences intake.

Reductions in dietary energy density are associated with weight loss in overweight and obese participants in the PREMIER trial

BACKGROUND

Dietary energy density (ED) reductions are associated with energy intake (EI) reductions. Little is known about influences on body weight (BW).

OBJECTIVES

We examined the effects of behavioral interventions on ED values and explored how 6-mo ED changes relate to BW.

DESIGN

Prehypertensive and hypertensive persons were randomly assigned to 1 of 3 groups: the established group received an 18-session intervention implementing well-established hypertension recommendations (eg, weight loss, sodium reduction, and physical activity), the established+Dietary Approaches to Stop Hypertension (DASH) group received an 18-session intervention also implementing the DASH diet, and the advice group received 1 session on these topics. Two 24-h dietary recalls were collected (n=658).

RESULTS

Each group had significant declines in EI, ED, and BW. The established and established+DASH groups had the greatest EI and BW reductions. The established+DASH group had the greatest ED reduction and the greatest increase in the weight of food consumed. When groups were combined and analyzed by ED change tertiles, participants in the highest tertile (ie, largest ED reduction) lost more weight (5.9 kg) than did those in the middle (4.0 kg) or lowest (2.4 kg) tertile. Participants in the highest and middle tertiles increased the weight of food they consumed (300 and 80 g/d, respectively) but decreased their EI (500 and 250 kcal/d). Conversely, those in the lowest tertile decreased the weight of food consumed (100 g/d), with little change in EI. The highest and middle tertiles had favorable changes in fruit, vegetable, vitamin, and mineral intakes.

CONCLUSION

Both large and modest ED reductions were associated with weight loss and improved diet quality.

Incorporation of air into a snack food reduces energy intake

This study investigated how the air content of a familiar snack food affected energy intake and whether varying the method of serving the snack modified intake. We tested two versions of an extruded snack (cheese puffs) that were equal in energy density (5.7 kcal/g), but differed in energy per volume (less-aerated snack: 1.00 kcal/ml; more-aerated snack: 0.45 kcal/ml). In a within-subjects design, 16 women and 12 men consumed the snacks ad libitum in the laboratory during four afternoon sessions. A standard volume (1250 ml) of each snack was served once in a bowl and once in an opaque bag. Results showed significant differences in intake of the two snacks by energy (p=0.0003) and volume (p<0.0001); subjects consumed 21% less weight and energy (70+/-17 kcal) of the more-aerated snack than the less-aerated snack, although they consumed a 73% greater volume of the more-aerated snack (239+/-24 ml). These findings suggest that subjects responded to both the weight and volume of the snack. Despite differences in intake, hunger and fullness ratings did not differ across conditions. The serving method did not significantly affect intake. Results from this study indicate that incorporating air into food provides a strategy to reduce energy intake from energy-dense snacks.

Sensory-specific satiety with simple foods in humans: no influence of BMI?

OBJECTIVE

Olfacto-gustatory sensory-specific satiety plays an important role in the termination of food ingestion. A defect in this mechanism, by increasing food intake, could be a factor in development of overweight. The present study was conducted to explore whether sensory-specific satiety in the overweight may be different from that in normal-weight subjects.

SUBJECTS

144 subjects (half men, half women; age range: 17-62 years; BMI range: 17-39 kg m(-2)).

MEASUREMENTS

Olfactory pleasure (OP) and flavor pleasure (FP) were evaluated before and after ingestion of a single chosen food. Six foods from three classes were offered: cucumber and tomato, pineapple and banana, and peanut and pistachio. According to the subjects' preference for one of them, subjects were classified into six groups (24 subjects each with equal sex ratio). The experimental sequence was (1) evaluation of the six foods (OP), (2) ad libitum intake of the preferred food (FP) and (3) second evaluation of the six foods (OP).

RESULTS

Food intake was limited by sensory-specific satiety (that is, a decline in FP for the ingested food) in overweight subjects just as it was in the leanest. There was no significant correlation between BMI and hedonic parameters (OP and FP) or intakes (quantity and volume). Pre-ingestive OP and FP correlated with the ingested food's weight (OP: r=0.468; FP: r=0.415; P<0.01), volume (OP: r=0.428; FP: r=0.407; P<0.01) and intake duration (OP: r=0.184; FP: r=0.343; P<0.05). The decline in OP, but not in FP, correlated with ingested weight (r=0.271, P<0.01) and volume (r=0.263, P<0.01) but not with duration.

CONCLUSION

After intake of a single food, olfacto-gustatory sensory-specific satiety correlated with the ingested food's weight and volume and with the duration of ingestion, but not with bodyweight. This suggests that overweight and lean subjects have similar hedonic control of food intake with simple foods.

High-fibre, low-fat diet predicts long-term weight loss and decreased type 2 diabetes risk: the Finnish Diabetes Prevention Study

AIMS/HYPOTHESIS

The aim of this study was to investigate the association of dietary macronutrient composition and energy density with the change in body weight and waist circumference and diabetes incidence in the Finnish Diabetes Prevention Study.

SUBJECTS AND METHODS

Overweight, middle-aged men (n=172) and women (n=350) with impaired glucose tolerance were randomised to receive either 'standard care' (control) or intensive dietary and exercise counselling. Baseline and annual examinations included assessment of dietary intake with 3-day food records and diabetes status by repeated 75-g OGTTs. For these analyses the treatment groups were combined and only subjects with follow-up data (n=500) were included.

RESULTS

Individuals with low fat (<median) and high fibre (>median) intakes lost more weight compared with those consuming a high-fat (>median), low-fibre (<median) diet (3.1 vs 0.7 kg after 3 years). In separate models, hazard ratios for diabetes incidence during a mean follow-up of 4.1 years were (highest compared with lowest quartile) 0.38 (95% CI 0.19-0.77) for fibre intake, 2.14 (95% CI 1.16-3.92) for fat intake, and 1.73 (95% CI 0.89-3.38) for saturated-fat intake, after adjustment for sex, intervention assignment, weight and weight change, physical activity, baseline 2-h plasma glucose and intake of the nutrient being investigated. Compared with the low-fat/high-fibre category, hazard ratios were 1.98 (95% CI 0.98-4.02), 2.68 (95% CI 1.40-5.10), and 1.89 (95% CI 1.09-3.30) for low-fat/low-fibre, high-fat/high-fibre, and high-fat/low-fibre, respectively.

CONCLUSIONS/INTERPRETATION

Dietary fat and fibre intake are significant predictors of sustained weight reduction and progression to type 2 diabetes in high-risk subjects, even after adjustment for other risk factors.

Lifestyle strategies for weight control: experience from the Finnish Diabetes Prevention Study

Currently, in many European countries more than half the adult population is overweight; it hass become 'abnormal' to be of 'normal weight'. The risk of type 2 diabetes, CVD, hypertension and certain forms of cancer increase with increasing weight. Biological evolution has produced body-fat-regulating mechanisms that are more powerful in protecting against weight loss than against weight gain. The current environment offers constant availability of affordable palatable energy-rich foods, with no need to consume the energy through physical activity. The 'obesogenic' environment is to some extent a political issue, but it has been shown that the healthcare system can also have a role in preventing obesity-related morbidity. The Finnish Diabetes Prevention Study was the first controlled randomised study to show that individualised lifestyle counselling of individuals with high risk of developing type 2 diabetes can influence diet, physical activity and body weight, and that type 2 diabetes can be prevented, or at least postponed. Most importantly, lifestyle changes do not have to be extreme. If the population would adopt a lifestyle in line with the official nutrition recommendations, the obesity and diabetes trend could at least be stabilised.

Economic causes and consequences of obesity

Obesity is not only a health but also an economic phenomenon. This chapter (a) examines underlying economic causes, such as technological advancements, behind the obesity epidemic; (b) describes economic consequences of obesity, including increasing obesity-related medical expenditures; and (c) discusses the role of government in combating the obesity epidemic. Because of the high costs of obesity, and the fact that the majority of these costs are financed by taxpayers, there is a clear motivation for government to try to reduce these costs. However, because obesity may result from poor information and addictive behavior and/or as a result of living in an increasingly obesogenic environment, interventions will need to be multifaceted to ensure the best chance of success.

Position of the American Dietetic association: fat replacers

It is the position of the American Dietetic Association that the majority of fat replacers, when used in moderation by adults, can be safe and useful adjuncts to lowering the fat content of foods and may play a role in decreasing total dietary energy and fat intake. Moderate use of low-calorie, reduced-fat foods, combined with low total energy intake, could potentially promote dietary intake consistent with the objectives of Healthy People 2010 and the 2005 Dietary Guidelines for Americans . The obesity epidemic in the nation has been attributed to energy imbalance, mainly because of increased food consumption and/or sedentary lifestyle, or both. Evidence suggests that lowering total energy intake along with a reduction in total fat intake can have a substantial impact on body weight and risk of chronic diseases. Fat replacers are used to provide some or all of the functional properties of fat, while providing fewer calories than the fat being replaced, and are used in a variety of products, from baked goods to frozen desserts. Fat replacers can be effective only if they lower the total caloric content of the food and if the consumer uses these foods as part of a balanced meal plan. Consumers should not be led to believe that fat- and calorie-reduced products can be consumed in unlimited amounts. Fat replacers are most useful when they help with calorie control and when their use encourages the consumption of foods delivering important nutrients.