Comparison of the effects of aspartame and sucrose on appetite and food intake

Health outcomes of non-nutritive sweeteners: analysis of the research landscape

BACKGROUND

Food products containing non-nutritive sweeteners (NNSs) instead of sugar have become increasingly popular in the last decades. Their appeal is obviously related to their calorie-free sweet taste. However, with the dramatic increase in their consumption, it is reasonable and timely to evaluate their potential health benefits and, more importantly, potential adverse effects. The main aim of this scoping review was to map the evidence about health outcomes possibly associated with regular NNS consumption by examining the extent, range, and nature of research activity in this area.

METHODS

We systematically searched Ovid MEDLINE, EMBASE and the Cochrane CENTRAL databases for studies on NNSs (artificial sweeteners or natural, non-caloric sweeteners, either used individually or in combination) using text terms with appropriate truncation and relevant indexing terms. All human studies investigating any health outcomes of a NNS intervention or exposure were eligible for inclusion. No studies were excluded based on language, study design or methodological quality. Data for each health outcome were summarized in tabular form and were discussed narratively.

RESULTS

Finally, we included 372 studies in our scoping review, comprising 15 systematic reviews, 155 randomized controlled trials (RCTs), 23 non-randomized controlled trials, 57 cohort studies, 52 case-control studies, 28 cross sectional studies and 42 case series/case reports. In healthy subjects, appetite and short term food intake, risk of cancer, risk of diabetes, risk of dental caries, weight gain and risk of obesity are the most investigated health outcomes. Overall there is no conclusive evidence for beneficial and harmful effects on those outcomes. Numerous health outcomes including headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were investigated in fewer studies and further research is needed. In subjects with diabetes and hypertension, the evidence regarding health outcomes of NNS use is also inconsistent.

CONCLUSIONS

This scoping review identifies the needs for future research to address the numerous evidence gaps related to health effects of NNSs use.It also specifies the research questions and areas where a systematic review with meta-analyses is required for the proper evaluation of health outcomes associated to regular NNSs consumption.

Comparison of oro-sensory exposure duration and intensity manipulations on satiation

Oro-sensory exposure (OSE) is an important factor in the regulation of food intake with increasing OSE leading to lower food intake. Oral processing time and taste intensity both play an important role in OSE but their individual contribution to satiation is unknown. We aimed to determine the independent and combined effects of oral processing time and taste intensity on satiation. Fifty eight participants (23±9y, BMI 22±2kg/m²) participated in a 2×2 factorial randomized crossover study in which they consumed one of four gel-based model foods until satiation during four sessions. Model foods were offered ad libitum and differed in texture (soft or hard texture, yielding shorter and longer oral processing time) and sweetness (low or high intensity). Model foods were isocaloric and were matched for flavor and palatability. Outcome measures were intake of the model food and the microstructure of eating behavior, such as number of chews and eating rate. There was an overall significant effect of texture (p<0.001) but not sweetness (p=0.33) on intake with a 29.2% higher intake of the soft model foods compared to the hard model foods. After correction for palatability the difference in intake between the soft and hard model foods was 21.5% (p<0.001). The number of chews was significantly lower for the soft (10.1±6.2) than for the hard (26.9±6.2) model foods (p<0.001), which resulted in a significantly lower eating rate (soft, 26.3±10.2 and hard, 15.3±7.1g/min, p<0.001). These results show that increasing texture hardness of gel model foods decreases food intake independent of sweet taste intensity. The higher number of chews and faster eating rate may cause this effect. In conclusion, oro-sensory exposure duration rather than taste intensity appears to be the main determinant of food intake.

The role of sweet taste in satiation and satiety

Increased energy consumption, especially increased consumption of sweet energy-dense food, is thought to be one of the main contributors to the escalating rates in overweight individuals and obesity globally. The individual’s ability to detect or sense sweetness in the oral cavity is thought to be one of many factors influencing food acceptance, and therefore, taste may play an essential role in modulating food acceptance and/or energy intake. Emerging evidence now suggests that the sweet taste signaling mechanisms identified in the oral cavity also operate in the gastrointestinal system and may influence the development of satiety. Understanding the individual differences in detecting sweetness in both the oral and gastrointestinal system towards both caloric sugar and high intensity sweetener and the functional role of the sweet taste system may be important in understanding the reasons for excess energy intake. This review will summarize evidence of possible associations between the sweet taste mechanisms within the oral cavity, gastrointestinal tract and the brain systems towards both caloric sugar and high intensity sweetener and sweet taste function, which may influence satiation, satiety and, perhaps, predisposition to being overweight and obesity.

The effect of sugar-free versus sugar-sweetened beverages on satiety, liking and wanting: an 18 month randomized double-blind trial in children

BACKGROUND

Substituting sugar-free for sugar-sweetened beverages reduces weight gain. A possible explanation is that sugar-containing and sugar-free beverages cause the same degree of satiety. However, this has not been tested in long-term trials.

METHODS

We randomized 203 children aged 7-11 years to receive 250 mL per day of an artificially sweetened sugar-free beverage or a similarly looking and tasting sugar-sweetened beverage. We measured satiety on a 5-point scale by questionnaire at 0, 6, 12 and 18 months. We calculated the change in satiety from before intake to 1 minute after intake and 15 minutes after intake. We then calculated the odds ratio that satiety increased by 1 point in the sugar-group versus the sugar-free group. We also investigated how much the children liked and wanted the beverages.

RESULTS

146 children or 72% completed the study. We found no statistically significant difference in satiety between the sugar-free and sugar-sweetened group; the adjusted odds ratio for a 1 point increase in satiety in the sugar group versus the sugar-free group was 0.77 at 1 minute (95% confidence interval, 0.46 to 1.29), and 1.44 at 15 minutes after intake (95% CI, 0.86 to 2.40). The sugar-group liked and wanted their beverage slightly more than the sugar-free group, adjusted odds ratio 1.63 (95% CI 1.05 to 2.54) and 1.65 (95% CI 1.07 to 2.55), respectively.

CONCLUSIONS

Sugar-sweetened and sugar-free beverages produced similar satiety. Therefore when children are given sugar-free instead of sugar-containing drinks they might not make up the missing calories from other sources. This may explain our previous observation that children in the sugar-free group accumulated less body fat than those in the sugar group.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00893529 http://clinicaltrials.gov/show/NCT00893529.

Comparison of three methods to reduce energy density. Effects on daily energy intake

Reductions in food energy density can decrease energy intake, but it is not known if the effects depend on the way that energy density is reduced. We investigated whether three methods of reducing energy density (decreasing fat, increasing fruit and vegetables, and adding water) differed in their effects on energy intake across the day. In a crossover design, 59 adults ate breakfast, lunch, and dinner in the laboratory once a week for 4 weeks. Across conditions, the entrées were either standard in energy density or were reduced in energy density by 20% using one of the three methods. Each meal included a manipulated entrée along with unmanipulated side dishes, and all foods were consumed ad libitum. Reducing the energy density of entrées significantly decreased daily energy intake compared to standard entrées (mean intake 2667 ± 77 kcal/day; 11,166 ± 322 kJ/day). The mean decrease was 396 ± 44 kcal/day (1658 ± 184 kJ/day) when fat was reduced, 308 ± 41 kcal/day (1290 ± 172 kJ/day) when fruit and vegetables were increased, and 230 ± 35 kcal/day (963 ± 147 kJ/day) when water was added. Daily energy intake was lower when fat was decreased compared to the other methods. These findings indicate that a variety of diet compositions can be recommended to reduce overall dietary energy density in order to moderate energy intake.

Does diet-beverage intake affect dietary consumption patterns? Results from the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial

BACKGROUND

Little is understood about the effect of increased consumption of low-calorie sweeteners in diet beverages on dietary patterns and energy intake.

OBJECTIVE

We investigated whether energy intakes and dietary patterns were different in subjects who were randomly assigned to substitute caloric beverages with either water or diet beverages (DBs).

DESIGN

Participants from the Choose Healthy Options Consciously Everyday randomized clinical trial (a 6-mo, 3-arm study) were included in the analysis [water groups: n = 106 (94% women); DB group: n = 104 (82% women)]. For energy, macronutrient, and food and beverage intakes, we investigated the main effects of time, treatment, and the treatment-by-time interaction by using mixed models.

RESULTS

Overall, the macronutrient composition changed in both groups without significant differences between groups over time. Both groups reduced absolute intakes of total daily energy, carbohydrates, fat, protein, saturated fat, total sugar, added sugar, and other carbohydrates. The DB group decreased energy from all beverages more than the water group did only at month 3 (P-group-by-time < 0.05). Although the water group had a greater reduction in grain intake at month 3 and a greater increase in fruit and vegetable intake at month 6 (P-group-by-time < 0.05), the DB group had a greater reduction in dessert intake than the water group did at month 6 (P-group-by-time < 0.05).

CONCLUSIONS

Participants in both intervention groups showed positive changes in energy intakes and dietary patterns. The DB group showed decreases in most caloric beverages and specifically reduced more desserts than the water group did. Our study does not provide evidence to suggest that a short-term consumption of DBs, compared with water, increases preferences for sweet foods and beverages. This trial was registered at clinicaltrials.gov as NCT01017783.

Effects of chewing gum on short-term appetite regulation in moderately restrained eaters

Orosensory stimulation is an important contributing factor to the development of satiation. Providing orosensory stimulation with few calories may satisfy appetite and help to suppress cravings for high energy snacks. This may be a useful strategy for those motivated to lose or maintain weight. The present study tested the hypothesis that chewing sweetened gum will reduce subjective appetite and subsequent snack intake in moderately restrained eaters. Within-subjects, repeated measures study, sixty healthy participants (53 women; body mass index, in kg/m(2): 26.2±4.5) came to the laboratory 4 times for a standard lunch. Immediately after this meal, participants rated hunger, appetite and cravings for sweet and salty snacks every hour until they returned to the laboratory 3 h later for snack. On two occasions during this 3 h period participants chewed gum for at least 15 min at hourly intervals (45 min) and on two occasions no gum was chewed. On two occasions salty snacks were offered and on two occasions sweet snacks were provided. A small but significant reduction in snack intake was observed, chewing gum reduced weight of snack consumed by 10% compared to no gum (p<0.05). Overall, chewing gum for at least 45 min significantly suppressed rated hunger, appetite and cravings for snacks and promoted fullness (p<0.05). This study demonstrated some benefit of chewing gum which could be of utility to those seeking an aid to appetite control.

Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels

Consumption of sugar-sweetened beverages may be one of the dietary causes of metabolic disorders, such as obesity. Therefore, substituting sugar with low calorie sweeteners may be an efficacious weight management strategy. We tested the effect of preloads containing stevia, aspartame, or sucrose on food intake, satiety, and postprandial glucose and insulin levels.

DESIGN

19 healthy lean (BMI=20.0-24.9) and 12 obese (BMI=30.0-39.9) individuals 18-50 years old completed three separate food test days during which they received preloads containing stevia (290kcal), aspartame (290kcal), or sucrose (493kcal) before the lunch and dinner meal. The preload order was balanced, and food intake (kcal) was directly calculated. Hunger and satiety levels were reported before and after meals, and every hour throughout the afternoon. Participants provided blood samples immediately before and 20min after the lunch preload. Despite the caloric difference in preloads (290kcal vs. 493kcal), participants did not compensate by eating more at their lunch and dinner meals when they consumed stevia and aspartame versus sucrose in preloads (mean differences in food intake over entire day between sucrose and stevia=301kcal, p<.01; aspartame=330kcal, p<.01). Self-reported hunger and satiety levels did not differ by condition. Stevia preloads significantly reduced postprandial glucose levels compared to sucrose preloads (p<.01), and postprandial insulin levels compared to both aspartame and sucrose preloads (p<.05). When consuming stevia and aspartame preloads, participants did not compensate by eating more at either their lunch or dinner meal and reported similar levels of satiety compared to when they consumed the higher calorie sucrose preload.

Habitual high and low consumers of artificially-sweetened beverages: Effects of sweet taste and energy on short-term appetite

This study investigated the effects of sweet taste and energy on subsequent short-term appetite in female habitual high and low consumers of artificially-sweetened beverages. The study was based on the proposal that effects of sweet taste on appetite may differ as a result of the habitual experience of sweetness with or without energy. Following a repeated measures design, 10 female habitual high and 10 female habitual low consumers of artificially-sweetened beverages consumed a non-sweet/low-energy, sweet/low-energy, and sweet/high-energy preload, and cumulative test meal intake (gram, kJ.), cumulative total intake (gram, kJ.), and subjective perceptions of appetite were subsequently assessed. Different effects of sweet taste were found in habitual high and low consumers of artificially-sweetened beverages. Low consumers of artificially-sweetened beverages demonstrated an increase in appetite in response to sweet taste, whereas high consumers did not. Effects of energy on appetite did not differ between consumers. The effects of energy are unsurprising. The effects of sweet taste, however, are of interest. The lack of response to sweet taste in high consumers of artificially-sweetened beverages can be explained as a result of the repeated experience of sweetness without energy by these consumers. This lack of response suggests an adaptation to sweet taste as a result of the habitual dietary pattern of these consumers.

Blood glucose and meal patterns in time-blinded males, after aspartame, carbohydrate, and fat consumption, in relation to sweetness perception

In a study of the impact of aspartame, fat, and carbohydrate on appetite, we monitored blood glucose continuously for 431 (se 16) min. Ten healthy males (19–31 years) participated in three time-blinded visits. As blood glucose was monitored, appetite ratings were scored at randomized times. On the first meal initiation, volunteers consumed one of three isovolumetric drinks (aspartame, 1 MJ simple carbohydrate, and 1 MJ high-fat; randomized order). High-fat and high-carbohydrate foods were available ad libitum subsequently. Blood glucose patterns following the carbohydrate drink (+1·78 (se 0·28) mmol/l in 38 (se 3) min) and high-fat drink (+0·83 (se 0·28) mmol/l in 49 (se 6) min) were predictive of the next intermeal interval (R 0·64 and R 0·97 respectively). Aspartame ingestion was followed by blood glucose declines (40 % of subjects), increases (20 %), or stability (40 %). These patterns were related to the volunteers' perception of sweetness of the drink (R 0·81, P = 0·014), and were predictive of subsequent intakes (R -0·71, P = 0·048). For all drinks combined, declines in blood glucose and meal initiation were significantly associated (χ2 16·8, P < 0·001), the duration of blood glucose responses and intermeal intervals correlated significantly (R 0·715, P = 0·0001), and sweetness perception correlated negatively with hunger suppression (R -0·471, P = 0·015). Effects of fat, carbohydrate, and aspartame on meal initiation, meal size, and intermeal interval relate to blood glucose patterns. Varied blood glucose responses after aspartame support the controversy over its effects, and may relate to sweetness perception.

Cues to overeat: psychological factors influencing overconsumption

Human food intake is driven by necessity, but modern industrialized societies are characterized by food surfeit and an increasingly ‘obesogenic’ environment. This environment tends to discourage energy expenditure and to facilitate energy intake. The amount eaten in any given eating episode depends less on internal need state and more on environmental contextual factors such as the availability of highly-palatable energy-dense foods. In addition, the process of satiation can easily be disrupted by the introduction within a meal of different foods (variety effect), the presence of others (social context) and competing tasks (distraction). Properties of ingestants such as alcohol promote food intake and characteristics of individuals make them more or less susceptible to situational cues to overeat. In the present review the role of each of these environmental factors in promoting overconsumption are considered and the extent to which these factors might contribute to long-term weight regulation is discussed.

Does modification of olfacto-gustatory stimulation diminish sensory-specific satiety in humans?

Alimentary sensory pleasure is an important factor in ingestive behavior. Renewal of olfacto-gustatory pleasure by introducing new foods or through seasoning of previously consumed food might increase intake.

OBJECTIVES

To explore whether sensory-specific satiety (SSS) for a food could be modulated, either by introducing a novel food or by a modification of sensory stimulation via seasoning the food just eaten.

METHODS

180 out of 242 subjects were distributed over 3 experiments involving ad libitum intake of one of 6 fresh foods (cucumber, tomato, pineapple, banana, peanut, pistachio). Blindfolded subjects reported their sensations for the foods on 3 parameters before and after intake of an olfactorily chosen food: Olfactory pleasure (OP), Specific appetite (SA) and Stimulus-Induced Salivation (SIS). EXP. 1: One chosen food was repeatedly presented orthonasally and rated before and after it was eaten. EXP. 2: A second food was olfactorily chosen and ingested after the first one. EXP. 3: The same food was offered again after seasoning.

RESULTS

2 min after ingestion, food intake was limited by SSS. OP, SA, SIS correlated with each other for eaten and non-eaten foods. OP for non-eaten foods increased (p<0.01) after ingestion of the chosen food to specific satiety. When the food just eaten was seasoned, OP increased (p<0.01) and led to additional intake (80% of first intake).

CONCLUSION

A reduction in SSS after introduction of a new flavor or after seasoning an ingested food was observed. Such a reduction has not previously been reported. This could hint at how food sensory variation leads to over-consumption.

Relationships of ratings of appetite to food intake in healthy older men and women

The aim of this study was to determine how rated appetite relates to the amount eaten in a meal in healthy older people. On two study days, 32 healthy older men (n = 16) and women (n = 16) aged 65-85 years, recruited by advertisement, consumed a standardised breakfast and 4 h later were offered lunch from which they could eat freely. Foods eaten at lunch were weighed and energy intake calculated from nutrient composition data. Appetite was assessed at baseline and at 30-min intervals between meals by line ratings of hunger, fullness, nausea and how much could be eaten. The optimum time for correlations both among appetite ratings and between appetite and lunch intake was just before the lunch. Mean coefficients of repeatability (21-38 mm) and correlation coefficients (0.67-0.71) at that point in time were similar to those reported previously in young adults. Thus, in older and well as young adults, the size of a meal is most closely related to rated appetite just before the meal.

Effects of a sweet and a nonsweet lunch on short-term appetite: differences in female high and low consumers of sweet/low-energy beverages

INTRODUCTION

Effects of sweet taste on short-term appetite are still being actively researched. This study investigates the proposal that the effects of sweet tastes on appetite may differ as a result of differing habitual experiences of sweetness with or without energy.

METHODS

Effects of sweet tastes on appetite were investigated in habitual high and low consumers of sweet/low-energy beverages. Sweet taste was manipulated in a preload lunch and appetite was subsequently measured using test meal intake and subjective ratings of general and specific appetites.

RESULTS

The effects of the sweet and nonsweet lunch on short-term appetite differed significantly in high and low consumers of sweet/low-energy beverages, in subjective ratings of appetite for something sweet [consumer x preload x time interaction F(12,126) = 2.68, P = 0.003] and appetite for something savoury [consumer x preload x time interaction F(12,126) = 3.17, P = 0.001]. Effects in low consumers of sweetness without energy demonstrate close association between taste and energy, whereas effects in high consumers suggest a dissociation between taste and energy in these consumers.

DISCUSSION

These findings provide a further indication that the short-term control of appetite varies according to the habitual pattern of dietary intake. The long-term experience of sweetness without energy influences appetite for sweet and savoury tastes.

Effects of sugar intake on body weight: a review

Weight reduction programmes are mainly focused on reducing intake of fat and sugar. In this review we have evaluated whether the replacement of dietary (added) sugar by low-energy sweeteners or complex carbohydrates contributes to weight reduction. In two experimental studies, no short-term differences in weight loss were observed after use of aspartame as compared to sugar in obese subjects following a controlled energy-restricted diet. However, consumption of aspartame was associated with improved weight maintenance after a year. In two short-term studies in which energy intake was not restricted, substitution of sucrose by artificial sweeteners, investigated mostly in beverages, resulted in lower energy intake and lower body weight. Similarly, two short-term studies, comparing the effect of sucrose and starch on weight loss in obese subjects did not find differences when the total energy intake was equal and reduced. An ad libitum diet with complex carbohydrates resulted in lower energy intake compared to high-sugar diets. In two out of three studies, this was reflected in lower body weight in subjects consuming the complex carbohydrate diet. In conclusion, a limited number of relatively short-term studies suggest that replacing (added) sugar by low-energy sweeteners or by complex carbohydrates in an ad libitum diet might result in lower energy intake and reduced body weight. In the long term, this might be beneficial for weight maintenance. However, the number of studies is small and overall conclusions, in particular for the long term, cannot be drawn.

Dietary energy density and weight regulation

Dietary energy density (ED) has been suggested as an important determinant of energy intake and, therefore, energy regulation. This review summarizes published studies on the effects of dietary ED on hunger, satiety, energy intake, and body weight in healthy individuals, and compares the relative effects of ED manipulated by dietary fat only, fat and fiber, water, and type of sweetener. In short-term studies, consumption of low-ED foods promotes satiety, reduces hunger, and decreases energy intake with no marked differences between different dietary manipulations used to change ED. In addition, low-ED diets promote moderate weight loss in long-term studies. In studies lasting longer than 6 months, weight loss was more than three times as great in individuals consuming diets both low in fat and high in fiber compared with diets only low in fat (-3.4 kg versus -1.0 kg). Combined, these studies suggest that diets low in fat and high in fiber may be the most effective low-ED diets for promoting weight loss. Further research is needed on the effects of dietary ED by changing water or sweetener content.

The use of visual analogue scales to assess motivation to eat in human subjects: a review of their reliability and validity with an evaluation of new hand-held computerized systems for temporal tracking of appetite ratings

This present paper reviews the reliability and validity of visual analogue scales (VAS) in terms of (1) their ability to predict feeding behaviour, (2) their sensitivity to experimental manipulations, and (3) their reproducibility. VAS correlate with, but do not reliably predict, energy intake to the extent that they could be used as a proxy of energy intake. They do predict meal initiation in subjects eating their normal diets in their normal environment. Under laboratory conditions, subjectively rated motivation to eat using VAS is sensitive to experimental manipulations and has been found to be reproducible in relation to those experimental regimens. Other work has found them not to be reproducible in relation to repeated protocols. On balance, it would appear, in as much as it is possible to quantify, that VAS exhibit a good degree of within-subject reliability and validity in that they predict with reasonable certainty, meal initiation and amount eaten, and are sensitive to experimental manipulations. This reliability and validity appears more pronounced under the controlled (but more artificial) conditions of the laboratory where the signal:noise ratio in experiments appears to be elevated relative to real life. It appears that VAS are best used in within-subject, repeated-measures designs where the effect of different treatments can be compared under similar circumstances. They are best used in conjunction with other measures (e.g. feeding behaviour, changes in plasma metabolites) rather than as proxies for these variables. New hand-held electronic appetite rating systems (EARS) have been developed to increase reliability of data capture and decrease investigator workload. Recent studies have compared these with traditional pen and paper (P&P) VAS. The EARS have been found to be sensitive to experimental manipulations and reproducible relative to P&P. However, subjects appear to exhibit a significantly more constrained use of the scale when using the EARS relative to the P&P. For this reason it is recommended that the two techniques are not used interchangeably.

Effects of sensory stimulation and post-ingestive consequences on satiation

This study investigated the influence of sensory stimulation, with and without post-ingestive consequences, on satiation by varying the form of a preload and the timing of a mixed meal presented after the preload. Twenty-four, normal-weight, non-dieting, college-aged women were randomized to different preload groups: water preload (Water), sip-and-spit energy-dense preload (Taste), or energy-dense preload (Taste/kcal). Volume of fluid consumed prior to the meal was controlled. All participants had sessions in which a meal was provided immediately (0 min) or 30 min after the preload. Results showed equal suppression of intake for participants receiving sensory stimulation from an energy-dense preload (Taste and Taste/kcal groups) in comparison to a water preload (Water group). No effect of time from preload to food consumption was found; the suppression of intake was similar whether the meal immediately followed the preload or was 30 min after the preload. These findings suggest that sensory aspects of food can influence satiation, and in the conditions of this study, had a larger influence on satiation than post-ingestive consequences.

Reasons for initiation and cessation of eating in obese men and women and the affective consequences of eating in everyday situations

Reasons for the initiation and termination of eating were investigated in 78 female and 36 male obese subjects following a weight control programme. Self-monitoring diaries were completed during a 24-h period, in which subjects selected the main reason for starting and stopping an eating episode. Additionally, subjects recorded mood before and after eating using visual analogue scales. Hunger was chosen as a reason to start eating in only 20% of cases. Environmental cues such as mealtime were selected as the main reason for the initiation of the majority of eating episodes. In contrast, self-assessments such as "I felt I had eaten enough" was the main reason for terminating eating (39.4%). Gender differences in the reasons for initiating eating revealed a greater tendency for men to initiate eating for environmental reasons than women, whereas the opposite was found for the termination of eating, with women more likely to stop eating for environmental reasons than men. Changes in affect during eating revealed a significant decline in negative emotions such as tension and tiredness, and in the heavier subjects a trend for increased happiness was observed following eating. As hunger was less commonly reported as a reason to start eating than external reasons, treatment strategies for the obese might benefit by targeting individual reasons for meal initiation.

Dietary compensation by humans for supplemental energy provided as ethanol or carbohydrate in fluids

Dietary compensation for energy provided as ethanol is reportedly limited. Whether this is a function of the ethanol or other aspect of the medium in which it is ingested is not known. Eight male and eight female adults ingested 1.08 liters of beer (5.0% ethanol w/v, 1891kJ), light beer (2.9% ethanol w/v, 1197kJ), no-alcohol beer (0.1% ethanol w/v, 816kJ), cola (1749kJ) or carbonated water (0kJ) every 3-4 days with a midday meal. Diet records were kept the preceding day and day of beverage ingestion. Energy intake was significantly higher each day an energy-bearing beverage was consumed relative to its preceding day. A literature review revealed dietary compensation for modifications of energy intake via fluids is less precise than when solid foods are manipulated. These findings demonstrate dietary adjustment for energy derived from ethanol is imprecise, but also indicate energy from carbohydrate elicits little dietary response when ingested in a beverage.

The reproducibility of subjective appetite scores

Although subjective appetite scores are widely used, studies on the reproducibility of this method are scarce. In the present study nine healthy, normal weight, young men recorded their subjective appetite sensations before and during 5 h after two different test meals A and B. The subjects tested each meal twice and in randomized order. Visual analogue scale (VAS) scores, 10 cm in length, were used to assess hunger, satiety, fullness, prospective food consumption and palatability of the meals. Plasma glucose and lactate concentrations were determined concomitantly. The repeatability was investigated for fasting values, delta-mean 5 h and mean 5 h values, delta-peak/nadir and peak/nadir values. Although the profiles of the postprandial responses were similar, the coefficients of repeatability (CR = 2SD) on the mean differences were large, ranging from 2.86 to 5.24 cm for fasting scores, 1.36 to 1.88 cm for mean scores, 2.98 to 5.42 cm for delta-mean scores, and 3.16 to 6.44 cm for peak and delta-peak scores. For palatability ratings the CR values varied more, ranging from 2.38 (taste) to 8.70 cm (aftertaste). Part of the difference in satiety ratings could be explained by the differences in palatability ratings. However, the low reproducibility may also be caused by a conditioned satiation or hunger due to the subjects' prior experience of the meals and therefore not just be a reflection of random noise. It is likely, however, that the variation in appetite ratings is due both to methodological day-to-day variation and to biological day-to-day variation in subjective appetite sensations.

Intense sweeteners and the control of appetite

The sensation of sweet taste without calories has been said to increase appetite and promote food consumption. Regular use of intense sweeteners might therefore lead to a paradoxical weight gain. These alarmist reports have not been confirmed by recent experimental data. There is no evidence that the addition of an intense sweetener to a plain stimulus promotes appetite or results in increased food consumption during some later meal. While replacing sugars with intense sweeteners (with attendant decrease in energy) has been said to result in energy compensation, published studies have variously reported perfect compensation, partial compensation, or no compensation at all, depending on the conditions used. Longer-term studies are needed to assess chronic effects of intense sweeteners on dietary compliance and the control of body weight.

Sweeteners: state of knowledge review

Sweeteners are widely used in the food and pharmaceutical industry. The purpose of this paper is to review our current knowledge of sweet taste from chemical, biochemical, electrophysiological, psychophysical, and psychological points of view. The most common sweetners likely to be used in food and pharmaceuticals will be examined in detail. First, the chemical structures of sweet compounds including saccharides, diterpene glycosides, polyols, amino acids, dipeptides, and other nonsugars will be discussed. Second, biochemical approaches to understanding sweetner receptors will be reviewed. Third, electrophysiological and behavioral approaches to understanding sweetner receptors will be discussed. Fourth, psychophysical studies in humans will be shown to be consistent with biochemical and neurophysiological data. In addition, the basic mechanisms of sweet taste revealed by psychophysical studies will be given, including the role of multiple receptor sites, hydrogen bonding, and sodium transport. Finally, the factors that affect preference for sweet taste including the psychological and physiological variables associated with sweet preference will be explored.

Consuming aspartame with and without taste: differential effects on appetite and food intake of young adult males

Despite some reports that aspartame (APM)-sweetened beverages may increase subjective appetite, previously we demonstrated that drinking 280 ml of an APM-sweetened soft drink (170 mg APM) had no effect on appetite, and 560 ml of the same soft drink (340 mg APM) reduced appetite. The present study examined this appetite reduction to determine its cause. Eighteen normal weight young adult males received five treatments (beverage preloads) at 1100 h in a randomized order, one per week: 280 ml of carbonated mineral water (CMW) (control), 560 ml of CMW, 280 ml of CMW with 340 mg of encapsulated APM, 280 ml of CMW sweetened with 340 mg APM, 560 ml of an APM-sweetened soft drink (340 mg APM). Subjective hunger and food appeal were measured from 0930 a.m. to 1230 h, and food intake from a buffet lunch offered at 1205 h was measured. Treatment had no effect on food intake or macronutrient selection. Both 560 ml of CMW or soft drink suppressed appetite, although 280 ml of APM-sweetened mineral water significantly increased subjective appetite relative to the control. Encapsulated APM had no effect on appetite. Therefore, appetite reduction following consumption of an APM-sweetened drink is likely due to drink volume and not the APM content. In addition, consuming APM-sweetened CMW produces a short-term increase in subjective appetite.

Soft drinks with aspartame: effect on subjective hunger, food selection, and food intake of young adult males

Ingestion of aspartame-sweetened beverages has been reported to increase subjective measures of appetite. This study examined the effects of familiar carbonated soft drinks sweetened with aspartame on subjective hunger, energy intake and macronutrient selection at a lunch-time meal. Subjects were 20 normal weight young adult males, classified as either restrained or nonrestrained eaters. Four treatments of carbonated beverages included 280 ml of mineral water, one can of a soft drink (280 ml) consumed in either 2 or 10 minutes, or two cans of a soft drink (560 ml) consumed in 10 minutes, administered at 11:00 a.m. Subjective hunger and food appeal were measured from 9:30 a.m. to 12:30 p.m., and food intake data were obtained from a buffet lunch given at 12:00 noon. There were no treatment effects on energy intake, macronutrient selection or food choice at the lunch-time meal, or food appeal, though restrained eaters consumed more than nonrestrained eaters in all four treatment conditions. Consumption of two soft drinks (560 ml, 320 mg aspartame) significantly reduced subjective hunger from 11:05 a.m. to 11:30 a.m. compared to one soft drink (280 ml, 160 mg aspartame) or 280 ml of mineral water. Thus ingestion of soft drinks containing aspartame did not increase short-term subjective hunger or food intake.

Effects of temperature and mode of presentation of juice on hunger, thirst and food intake in humans

Foods differ in their satiating effects; temperature and mode of presentation may be factors important for these differences. We tested the effects of these two variables in normal weight, non-dieting males and females using vegetable juice. The juice was offered as a preload, with females receiving 300 g and males receiving 400 g under conditions that systematically varied temperature (60-62 degrees C vs. 1 degrees C) and presentation (served in mug vs. bowl with spoon); a no-preload condition was also included. Each preload was followed within 5 min by a second course of grilled cheese sandwiches. In the males, intake was significantly lower after cold but not hot preloads in comparison to the no-preload condition; however, intakes following the hot and cold preloads did not differ significantly. Males also reported a significantly greater decline in thirst following the cold preloads. Temperature of the preloads did not affect food intake or thirst in the female subjects. Neither group was affected by the mode of presentation of the preloads. Further studies with other types of foods and drinks are needed to clarify whether temperature or mode of presentation can influence satiating efficiency.

Hunger ratings are not a valid proxy measure of reported food intake in humans

Hunger ratings have been used as proxy measures of food intake although their validity has not been established. To address this issue, 12 female and 12 male adults of normal weight recorded food intake and hunger ratings every waking hour for 7 consecutive days. Discrepancies were noted in the correlation between hunger ratings and computed energy intake on weekdays vs. weekends, and no significant correlations were observed for individual subjects. Eating often occurred when hunger ratings were low or had not increased, and few individuals displayed a significant correlation between hunger ratings and number of eating occurrences. It was concluded that hunger ratings are not a valid index of energy intake computed from food records or number of eating occurrences.

Effects of aspartame and sucrose on hunger and energy intake in humans

Physiological and behavioral responses to high intensity sweeteners have been poorly characterized, leading to questions regarding their utility in weight management regimens. To address this issue, studies must independently control attributes such as the taste properties, chemical composition and energy contribution of a given sweetener, as well as subject expectations of its effects. In the present study, 24 adults of normal weight consumed breakfasts including unsweetened or sweetened (sucrose or aspartame) cereal for 5 days, during which hunger and energy intake were monitored. The cereals were rated as equally sweet and pleasant and were equicaloric. Half of the subjects were aware of the cereal composition. Neither sweet taste nor aspartame alone significantly affected reported hunger, daily energy intake or subsequent selection of foods with varying taste qualities. Energy intake tended to be more strongly influenced by perceptions of the energy value of the experimental breakfast. Thus, this study failed to find an appetite stimulating effect of either sweetness or sweetener (aspartame or sucrose).

Hunger and food intake following consumption of low-calorie foods

Although high-intensity sweeteners are widely used to decrease the energy density of foods, little is known about how this affects hunger and food intake. We have studied the effects of consumption of commercially available foods sweetened with either sucrose or aspartame on subjective appetite ratings and food intake. When normal-weight non-dieting males and females were given large portions of either a high- or low-calorie pudding or jello and instructed to eat as much as they liked, they ate similar weights of the different caloric versions of each food. Despite the resulting difference in caloric intake (up to 206 kcal), subjects showed only a non-significant trend towards caloric compensation when presented with a variety of foods 2 h later. Total caloric intake (preload plus test meal) did not differ between conditions. Ratings of hunger, desire to eat, the amount subjects wanted to eat, and the pleasantness of the taste of the eaten food were similarly decreased and fullness similarly increased by consumption of the different caloric versions of the foods. Awareness of the caloric content of the foods did not influence intake or appetite in that both informed and uniformed subjects responded similarly in the tests. Thus reduced calorie foods suppressed ratings of hunger for several hours after consumption, but were not associated with a significant reduction in total energy intake.

Aspartame: effect on lunch-time food intake, appetite and hedonic response in children

Two experiments were conducted, each with 20 healthy 9-10-year-old children. After an overnight fast, subjects were given a standardized breakfast at 0830 hrs, the treatments at 1030 hrs, and a lunch containing an excess of foods at 1200 hrs. Visual analog scales of hunger, fullness, and desire to eat were administered 5 min before and 20 and 85 min after treatment. Lunch-time food intake was measured. In experiment 1, either aspartame (34 mg/kg), or the equivalent sweetness of sodium cyclamate, was given in an ice slurry (300 ml) of unsweetened strawberry Kool-Aid with carbohydrate (1.75 g/kg polycose). In experiment 2, drinks (300 ml) contained either sucrose (1.75 g/kg) or aspartame (9.7 mg/kg). In both experiments, significant meal- and time-dependent effects were observed for subjective feelings of hunger, fullness and desire to eat. Treatments, however, did not affect either subjective feelings of appetite or lunch-time food intake. Thus, aspartame consumed without or with carbohydrate, did not affect either hunger or food intake of children when compared with the sweeteners sodium cyclamate and sucrose, respectively.

Children's food intake following drinks sweetened with sucrose or aspartame: time course effects

In two experiments, 2-5-year-old children's responsiveness to caloric density cues was examined. In a preloading protocol, consumption of fixed volumes of drinks (205 ml in Experiment 1; 150 ml in Experiment 2), sweetened with sucrose, aspartame, aspartame plus low glucose maltodextrin, or a water control, was followed by ad lib consumption from among a variety of foods. Caloric drinks had about 90 kcal in Experiment 1, 65 kcal in Experiment 2. The delay interval between the preload and the ad lib consumption was 0, 30 or 60 minutes. In Experiment 1, 24 4- and 5-year-old children participated in only one delay interval, while in Experiment 2, all 20 2- and 3-year-old children were seen in all conditions. Results revealed evidence of caloric compensation, but no evidence of preload x time delay interaction. In both experiments, aspartame also produced a significant suppression of intake relative to water, primarily due to the pattern at 30 min following the preload. Across conditions, the suppression following aspartame was usually significantly less than that produced by the caloric sweet drinks, providing evidence for postingestive effects. In Experiment 1, suppression of intake was related to the children's preferences for the foods, not to macronutrient content; consumption of nonpreferred foods was most suppressed. Consumption of sweetened drinks as long as 1 hour prior to eating suppressed food intake, and this common feeding practice may also reduce dietary variety.

Sensory stimulation and energy density in the development of satiety

To determine the contribution of sensory stimulation to the changing hedonic response to foods, the effects of consuming very low-calorie and higher calorie versions of soup and jello on the subjective pleasantness of foods were compared. Subjects were 24 normal weight females with low dietary restraint. Half the subjects were given test meals of low- and high-calorie tomato soup and half were given low- and high-calorie orange jello. They rated the pleasantness of the appearance, smell, texture and taste of nine sample foods as well as hunger and stomach fullness before and 2, 20, 40 and 60 min after consumption of the test meal. After the 60 min rating subjects were offered as much as they wanted to eat of a second course of cheese on crackers. Despite differences in the energy density of the test meals, there were no significant differences in the weights of food eaten in either the first or second course and no significant compensation in the second course for the energy differences of the first course. No differential effects of the caloric manipulation were observed in terms of hunger or fullness or in the development, time course and magnitude of sensory-specific satiety. That very low-calorie foods can produce sensory-specific satiety indicates that the sensory properties of foods are important for the changing hedonic response to foods as they are consumed.