Interindividual variability in appetitive sensations and relationships between appetitive sensations and energy intake

BACKGROUND

Appetitive sensations (AS) are signals that guide eating behaviors. Marked short-term inter-individual variability in AS has been reported but the long-term stability of individual ratings and their dietary implications are not well characterized.

OBJECTIVES

This study explored the stability of inter-individual ratings of hunger, fullness and thirst for 17 weeks; determined the relationships between these sensations, eating patterns and energy intake (EI); as well as the associations between ratings and selected individual characteristics (age, gender, BMI).

METHODS

A 17-week observational study collected hourly appetitive ratings and dietary intake data from 97 (90 completers, 7 partial completers) healthy adults at weeks 1, 9, and 17.

RESULTS

There were marked and stable inter-individual differences over the 17 weeks for hunger (week 1 vs. week 9, r = 0.72 (p < 0.001); week 1 vs. week 17, r = 0.67 (p < 0.001); week 9 vs. week 17, r = 0.77 (p < 0.001)); fullness (week 1 vs. week 9 r = 0.74 (p < 0.001); week 1 vs. week 17, r = 0.71 (p < 0.001); week 9 vs. week 17, r = 0.81 (p < 0.001)); and thirst (week 1 vs. week 9 r = 0.82 (p < 0.001); week 1 vs. week 17, r = 0.81 (p < 0.001); week 9 vs. week 17, r = 0.88 (p < 0.001)). Cross-correlation functions revealed EI and eating pattern exerted stronger effects on AS than the reverse. However, the absolute effect sizes were small. Path analyses also indicated that there were weak relationships between AS and EI. No robust effects of the studied individual characteristics were observed.

CONCLUSION

This study found that acute and chronic sensations of hunger, fullness and thirst are relatively stable within individuals but vary markedly between individuals. In addition, the present data indicate AS are poorly associated with dietary patterns or with EI under conditions of relatively stable energy balance.

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

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

Systematic Review and Meta-Analysis on the Effect of Portion Size and Ingestive Frequency on Energy Intake and Body Weight among Adults in Randomized Controlled Feeding Trials

Energy intake is the product of portion size (PS)-the energy content of an ingestive event-and ingestive frequency (IF)-the number of ingestive events per unit time. An uncompensated alteration in either PS or IF would result in a change in energy intake and body weight if maintained over time. The objective of this meta-analysis was to assess the independent effects of PS and IF on energy intake and body weight among healthy adults in randomized controlled trials (RCTs). A total of 9708 articles were identified in PubMed, Web of Science, Cochrane, and CINAHL databases. The articles were divided among 10 researchers; each article was screened for eligibility by 2-3 independent reviewers. Exclusion criteria included: populations <19 y and >65 y, unhealthy populations (i.e. participants with an acute or chronic disease), assessments <24 h and <4 wk in duration for trials investigating energy intake or body weight, respectively. Controlled feeding trials (i.e. fixed energy intake) that manipulated IF and PS in the same study intervention (IF/PS) were evaluated separately and for the body weight outcome only. Twenty-two studies (IF = 4, PS = 14, IF/PS = 4) met the inclusion criteria. There was an insufficient number of studies to assess the effect of IF, PS, or IF/PS on body weight. There was heterogeneity in the effect sizes among all comparisons (I2 ≥75%). Consuming larger portion sizes was associated with higher daily energy intake [295 kcal (202, 388), n = 24; weighted mean differences (WMD) (95% CI), n = comparisons], and increased frequency of ingestive events was associated with higher energy intake [203 kcal (76, 330), n = 10]. Results from RCTs support that larger PS and greater IF are both associated with higher energy consumption. However, there is insufficient information to determine chronic effects on body weight. This protocol was registered at the International Prospective Register of Systematic Reviews (PROSPERO) as CRD42018104757.

Perceptual Quality of Nonesterified Fatty Acids Varies with Fatty Acid Chain Length

Nonesterified fatty acids (NEFA) are effective taste stimuli. The quality they impart has not been well characterized. Sourness, and "fattiness" have been reported, but an irritation component has also been described and how these transition with gradations of aliphatic chain length has not been systematically studied. This study examined intensity and quality ratings of NEFA ranging from C2 to C18. Oral sites and the time course of sensations were also monitored. Given all NEFA contain carboxylic acid moieties capable of donating hydrogen ions, the primary stimulus for sour taste, testing was conducted with and without sour adaptation to explore the contribution of sour taste across the range of NEFA. Short-chain NEFA (C2-C6) were rated as predominantly sour, and this was diminished in C2 and C4 by sour adaptation. Medium-chain NEFA (C8-C12) were rated as mainly irritating with long-chain NEFA (C18) described mostly as bitter. The latter may reflect the lack of "fatty" lexicon to describe the sensation. Short-chain NEFA were mostly localized to the anterior tongue and were of rapid onset. The sensation from medium-chain NEFA was attributed to the lateral tongue, whereas medium- and long-chain NEFA sensations were predominantly localized to the back of the tongue and throat and had a longer lag time. The findings indicate there is a systematic transition of NEFA taste quality and irritation with increments in chain length and this is consistent with multiple modes of transduction.

Fatty Acids Taste Intensity Ratings Before and After Sour Taste Adaptation

Objectives

Recent research indicates that the taste quality of fatty acids, called ‘Oleogustus’, differs from the traditionally accepted five basic tastes. However, the actual quality of the sensation has not been characterized. One question is whether there is a sour component because very short-chain fatty acids, like acetic acid, the sour tastant in vinegar, is structurally a fatty acid. The present study investigated the quality sensation of fatty acids of graded chain length.

Methods

Sensory stimuli were acetic acid, butyric acid, hexanoic acid, octanoic acid, decanoic acid, lauric acid, oleic acid, and linoleic acid emulsions and palmitic acid, stearic acid powder. The intensity of the samples before and after expectorating was measured. Next, participants repeatedly sipped, held for 5 seconds, and expectorated a sour solution (0.09% w/w) and rated the intensity on a gLMS until the intensity was lower than “weak”. After adaption to the sour solution, the intensity of the sample was measured before and after expectorating. Participants recorded the quality of each sample.

Results

The intensity of acetic acid was significantly lower after adaptation (P &lt; 0.04) that before adaptation and a similar trend was noted for butyric acid. The other fatty acids were not affected by adaptation. The intensities of all liquid samples except the octanoic acid solution showed a significant difference between before and after expectorating the samples. The intensities of acetic, butyric and hexanoic acids were lower after expectorating the samples than the intensities before expectorating the samples (P &lt; 0.05) while the intensities of decanoic acid, lauric acid, oleic acid, and linoleic acid (P &lt; 0.05) were lower after expectorating. There was no significant difference in intensity of the palmitic acid solution and the intensity of the stearic acid solution between before and after expectorating.

Conclusions

The results showed that fatty acids with chain lengths great than 4 have a unique taste other than the sourness. In addition, short-chain fatty acid solutions had higher intensity before expectorating the solutions while the medium- and long-chain fatty acid solutions had higher intensity after expectorating solutions, indicating that there is a different persistence time for fatty acid directly related to chain-length.

Funding Sources

This study has no sponsors.

Low Calorie Sweeteners Differ in Their Physiological Effects in Humans

Low calorie sweeteners (LCS) are prevalent in the food supply for their primary functional property of providing sweetness with little or no energy. Though tested for safety individually, there has been extremely limited work on the efficacy of each LCS. It is commonly assumed all LCS act similarly in their behavioral and physiological effects. However, each LCS has its own chemical structure that influences its metabolism, making each LCS unique in its potential effects on body weight, energy intake, and appetite. LCS may have different behavioral and physiological effects mediated at the sweet taste receptor, in brain activation, with gut hormones, at the microbiota and on appetitive responses. Further elucidation of the unique effects of the different commercially available LCS may hold important implications for recommendations about their use for different health outcomes.

Systematic Review and Meta-analysis of the Effect of Portion Size and Ingestive Frequency on Energy Intake and Body Weight Among Adults in Randomized Controlled Trials (P08-007-19)

Objectives

Total energy intake is the product of portion size (PS), the energy content of an ingestive event, and ingestive frequency (IF), the number of ingestive events per unit time. An alteration in either portion size or ingestive frequency, that is not compensated by the other, must result in a change in energy intake and, if maintained over time, body weight. The primary objective of this meta-analysis was to assess the independent effects of PS and IF on dietary energy intake and body weight among healthy adults in randomized controlled trials.

Methods

8,614 articles (duplicates removed) published through 2018 with no date restriction were identified with PubMed, Web of Science, Cochrane, and CINAHL databases. The articles were divided among ten researchers and each article was screened for eligibility by two to three independent reviewers. Exclusion criteria included: populations <19 y and >65 y, unhealthy, assessment <24 h in duration, and controlled feeding trials. Studies investigating the effect of IF or PS on body weight were at least 4 weeks in duration. Eleven articles (IF = 3, PS = 8) met the inclusion criteria. There were not enough articles to assess the effect of PS on body weight.

Results

There was significant heterogeneity in the effect sizes among all comparisons (I2 = >50%). Consuming smaller portion sizes was associated with lower 24 h energy intake [–135 kcal (–249, –21), n = 15; WMD (95% CI), n = comparisons]. In contrast, IF was not associated with a difference in 24 h energy intake [–103 kcal (–230, 24), n = 5], but was positively related to body weight in trials ≥6 wk duration [0.40 kg (0.70, 0.11), n = 4].

Conclusions

Results from RCTs support that greater PS but not IF is associated with higher daily energy consumption. However, IF is positively associated with increased body weight over time.

Funding Sources

NA