Systematic literature review shows that appetite rating does not predict energy intake

Augmented gut hormone response to feeding in older adults exhibiting low appetite

Age-related changes in gut hormones may play a role in anorexia of ageing. The aim of this study was to determine concentrations of ghrelin, PYY, and GLP-1 in older adults exhibiting an anorexia of ageing phenotype. Thirteen older adults with healthy appetite (OA-HA; 8f, 75 ± 7 years, 26.0 ± 3.2 kg m-2), fifteen older adults with low appetite (OA-LA; 10f, 72 ± 7 years, 23.6 ± 3.1 kg m-2), and twelve young adults (YA; 6f, 22 ± 2 years, 24.4 ± 2.0 kg m-2) completed the study. Healthy appetite and low appetite were determined based on BMI, habitual energy intake, self-reported appetite, and laboratory-assessed ad libitum lunch intake. Participants provided a fasted measure of subjective appetite and blood sample (0 min) before consuming a standardised breakfast (450 kcal). Appetite was measured and blood samples were drawn throughout a 240-min rest period. At 240 min, an ad libitum lunch meal was consumed. Relative intake at lunch (expressed as percentage of estimated total energy requirement) was lower for OA-LA (19.8 ± 7.7%) than YA (41.5 ± 9.2%, p < 0.001) and OA-HA (37.3 ± 10.0%, p < 0.001). Ghrelin suppression was greater for OA-LA (net AUC, -78719 ± 74788 pg mL-1·240min-1) than both YA (-23899 ± 27733 pg mL-1·240min-1, p = 0.016) and OA-HA (-21144 ± 31161 pg mL-1·240min-1, p = 0.009). There were trends for higher GLP-1 concentrations in OA-LA compared with YA at 90 min (8.85 ± 10.4 pM vs. 1.88 ± 4.63 pM, p = 0.073) and 180 min (5.00 ± 4.71 pM vs. 1.07 ± 2.83 pM, p = 0.065). There was a trend for a greater PYY response for OA-LA compared with OA-HA (net AUC p = 0.062). "Anorexigenic response score" - a composite score of gut hormone responses to feeding - showed greater anorexigenic response in OA-LA, compared with YA and OA-HA. No differences were seen in subjective appetite. These observations suggest augmented anorexigenic responses of gut hormones to feeding may be causal mechanisms of anorexia of ageing.

Appetite, food intake, and gut hormone responses to glycomacropeptide protein ingestion in older adults: A feasibility, acceptability, and pilot study

Glycomacropeptide (GMP) has a unique amino acid profile which may make less satiating than other dietary proteins. This study assessed the feasibility and likely acceptability of a leucine-enriched GMP drink and determined appetite response in older adults (OA). Thirteen OA (11f; 70 ± 4 years) were recruited for sensory assessments of a leucine-enriched GMP drink when mixed with water and with fruit smoothie, compared with whey protein isolate (WHEY). Participants also partook in a single focus group exploring acceptability to protein and supplementation. Separately, a counterbalanced, double-blind study with twelve OA (8f; 69 ± 3 years) was conducted to determine appetite and gut hormone responses. Fasting subjective appetite was recorded using visual analogue scales and a fasted venous blood sample was collected (to measures acyl-ghrelin, PYY, GLP-1, and CCK) before participants consumed either: GMP protein (27g + 3g leucine, 350 mL water), WHEY (30g, 350 mL water), or water. Participants rested for 240 min, with appetite measures and blood sampling throughout. An ad libitum pasta-based meal was then consumed. Sensory testing revealed low pleasantness rating for GMP in water vs. WHEY (16 ± 14 vs 31 ± 24, p = 0.016). GMP addition to smoothie reduced pleasantness (26 ± 21 vs. 61 ± 29, p = 0.009) and worsened the aroma (46 ± 15 vs. 69 ± 28, p = 0.014). The focus group revealed uncertainty of protein needs and a scepticism of supplements, with preference for food. Gut hormone response did not differ between GMP and WHEY (nAUC for all gut hormones p > 0.05). There was no difference between conditions for lunch ad libitum intake (549 ± 171 kcal, 512 ± 238 kcal, 460 ± 199 kcal for GMP, WHEY, and water, p = 0.175), or for subjective appetite response. Leucine-enriched GMP was not less satiating than WHEY, and low palatability and scepticism of supplements question the likely acceptability of GMP supplementation. Providing trusted nutritional advice and food enrichment/fortification may be preferred strategies for increasing protein intake in OA.

Anorexia of ageing is associated with elevated fasted and lower post-prandial ghrelin, independent of ghrelin O-acyltransferase

The role of ghrelin metabolism in anorexia of ageing is unclear. The aim of this study was to determine acyl-ghrelin, total ghrelin, and ghrelin O-acyltransferase concentrations when fasted and in responses to feeding in older adults exhibiting anorexia of ageing. Twenty-five older adults (OA; 15f, 74 ± 7 years, 24.5 kg·m-2) and twelve younger adults (YA; 6f, 21 ± 2 years, 24.4 kg·m-2) provided a fasted measure of subjective appetite and fasted blood sample (0 min) before consuming a standardised porridge breakfast meal (450 kcal). Appetite was measured every 30 min for 240 min and blood was sampled at 30, 60, 90, 120, 180 and 240 min while participants rested. At 240 min, an ad libitum pasta-based lunch meal was consumed. Older adults were identified as those with healthy appetite (HA-OA) or low appetite (LA-OA), based on habitual energy intake, self-report appetite, BMI, and ad libitum lunch intake. YA ate more at lunch (1108 ± 235 kcal) than HA-OA (653 ± 133 kcal, p = 0.007) and LA-OA (369 ± 168 kcal; p < 0.001). LA-OA, but not HA-OA, had higher fasted concentrations of acyl- and total ghrelin than YA (acyl-ghrelin: 621 ± 307 pg·mL-1 vs. 353 ± 166 pg·mL-1, p = 0.047; total ghrelin: 1333 ± 702 pg·mL-1 vs. 636 ± 251 pg·mL-1, p = 0.006). Acyl-ghrelin (60 min and 90 min) and total ghrelin (90 min) were suppressed to a greater extent for LA-OA than for YA (p < 0.05). No differences were observed in subjective appetite, acyl-to-total ghrelin ratio, or plasma GOAT content (p > 0.1). Higher fasting ghrelin and an augmented ghrelin response to feeding in LA-OA, but not HA-OA, suggests that alterations to ghrelin metabolism are not functions of ageing per se and may be independent causal mechanisms of anorexia of ageing.

Impact of Motivation for Eating Habits, Appetite and Food Satisfaction, and Food Consciousness on Food Intake and Weight Loss in Older Nursing Home Patients

BACKGROUND

This study analyzed data from the Long-term care Information system For Evidence (LIFE) database to examine the effects of motivation to eat, appetite and food satisfaction, and food consciousness on food intake and weight loss.

METHODS

Of the 748 nursing home residents enrolled in the LIFE database, 336 met the eligibility criteria for this cross-sectional study. Motivation to eat, appetite and food satisfaction, and food consciousness were rated on five-point Likert scales (e.g., good, fair, normal, not so good, and not good). We applied Spearman rank correlation coefficient and multiple regression analyses to analyze the relationships between these three items, daily energy and protein intake, and body weight loss over 6 months.

RESULTS

The mean participant age was 87.4±8.1 years and 259 (77%) were female. The required levels of care included-level 1, 1 (0%); level 2, 4 (1%); level 3, 107 (32%); level 4, 135 (40%); and level 5, 89 (27%). The mean daily energy intake was 28.2±7.8 kcal/kg. The mean daily protein intake was 1.1±0.3 g/kg. The mean weight loss over six months was 1.2±0.7 kg. We observed strong positive correlations among motivation to eat, appetite and food satisfaction, and food consciousness (r>0.8). These three items were significantly associated with higher daily energy intake but not with daily protein intake. Only appetite and food satisfaction were significantly associated with lower weight loss over six months.

CONCLUSION

The observed associations of appetite and food satisfaction suggest that these factors may be more important to assess than motivation to eat or food consciousness among older adult residents of long-term care facilities.

Development of Momentary Appetite Capture (MAC): A versatile tool for monitoring appetite over long periods

Understanding how an intervention impacts appetite in real-life settings and over several days remains a challenging and under-explored research question. To this end, we developed Momentary Appetite Capture (MAC), a form of ecological momentary assessment that combines automated text messaging with an online platform. Participants report their appetite using visual analogue scales (hunger, desire to eat, and fullness) and a virtual portion-size selection task. In two separate studies, we assessed the feasibility and test-retest reliability of MAC. Participants were prompted every 2 hours over a 14-hour window, and they repeated this assessment over two consecutive weekdays. For each participant, we calculated a daily time-averaged area under the curve (AUC) for each appetite measure. In Study One (N = 25) time-averaged AUC was significantly positively correlated across test days for hunger (r = 0.563, p = .003), desire to eat (r = 0.515, p = .008) and prospective portion size (r = 0.914, p < .001), but not for fullness (r = 0.342, p = .094). Participants completed 95% of MACs (380 of 400), and we used participant feedback to improve the MAC tool and study protocol for Study Two. In Study Two (N = 31), 94% of MACs were completed (468 of 496). Across days, time-averaged AUC was significantly positively correlated for hunger (r = 0.595, p = < .001), fullness (r = 0.501, p = .004), desire to eat (r = 0.585, p < .001), and prospective portion size (r = 0.757, p < .001). Together, these studies suggest that MAC could be an acceptable and reliable tool to track appetite throughout the day. In the future, MAC could be used to explore the impact of weight-loss interventions on natural fluctuations in appetite.

Differential effects of nutritive and non-nutritive sweet mouth rinsing on appetite in adults with obesity

BACKGROUND

Excessive added sugar intake has been associated with obesity; however, the effect of dietary sweetness on energy intake (EI) and appetite in adults with and without obesity has not yet been determined.

OBJECTIVE

To assess the effect of mouth rinses with and without energy and sweetness on measures of appetite, and to compare responses between subjects with body mass index (BMI) between 18.5 and 24.9 kg/m2 or ≥30 kg/m2.

METHODS

In this randomized, double-blind crossover study, 39 subjects (age 23±5y; 17 male, 22 female; BMI 18.5-24.9 kg/m2: n = 21; ≥30 kg/m2: n = 18) performed modified sham-feeding (MSF) with a mouth rinse containing either sucrose, sucralose, maltodextrin, or water for 2min before expectorating the solution. Blood sampling and subjective appetite assessments occurred at baseline (-5) and 15, 30, 60, and 90min post-MSF. After, EI was assessed at a buffet meal and post-meal appetite ratings were assessed hourly for 3h.

RESULTS

Post-MSF ghrelin increased for water vs. maltodextrin (water: p = 0.03). Post-MSF cholecystokinin increased following maltodextrin-MSF (p = 0.03) and sucralose-MSF (p = 0.005) vs. sucrose for those with BMI:18.5-24.9 kg/m2 only. There was greater post-MSF desire to eat in response to water vs. sucrose (p = 0.03) and reduced fullness with sucralose for those with BMI≥30 vs. 18.5-24.9 kg/m2 (p < 0.001). There was no difference in EI at the buffet meal by mouth rinse (p = 0.98) or by BMI (p = 0.12). However, there was greater post-meal fullness following sucralose-MSF vs. water (p = 0.03) and sucrose (p = 0.004) for those with BMI≥30 vs. 18.5-24.9 kg/m2.

CONCLUSION

Sucralose rinsing led to greater cephalic phase CCK release in adults with a BMI:18.5-24.9 kg/m2 only; however, ghrelin responses to unsweetened rinses were energy-specific for all adults. As subsequent EI was unaffected, further investigation of cephalic phase appetite is warranted.

Appetite and its association with mortality in patients with advanced cancer - a Post-hoc Analysis from the Palliative D-study

BACKGROUND

Loss of appetite is a common nutrition symptom in patients with cancer. Understanding the trajectory of appetite could be of clinical use for prognostication in palliative cancer care. Our primary aim was to explore the association between self-assessed appetite and mortality in patients suffering from advanced cancer. Secondary aims included the relation between fatigue, albumin levels and CRP/albumin ratio and mortality. We also aimed to study potential sex-differences in the associations.

METHODS

Post-hoc analyses were performed using data from the Palliative D-study comprising 530 patients with cancer admitted to palliative care. Appetite and fatigue were assessed with the Edmonton Symptom Assessment System (ESAS). Cox proportional hazards models were used to calculate Hazard ratios (HR) with 95% confidence intervals (CI) for exposures of appetite, fatigue, albumin and CRP/albumin ratio, and time from study inclusion to death or censoring. Analyses were also performed stratified by sex.

RESULTS

The follow-up time ranged between 7 to 1420 days. Moderate and poor appetite were significantly associated with a higher mortality rate compared to reporting a good appetite; HR 1.44 (95%CI: 1.16-1.79) and HR 1.78 (95%CI: 1.39-2.29), respectively. A higher mortality rate was also seen among participants reporting severe fatigue compared to those reporting no fatigue; HR 1.84 (95%CI:1.43-2.36). Participants with low albumin levels (< 25 g/L) and those in the highest tertile of CRP/albumin ratio, had higher mortality rates, HR 5.35 (95%CI:3.75-7.63) and HR 2.66 (95%CI:212-3.35), compared to participants with high albumin levels (> 36 g/L) and those in lowest tertile of CRP/albumin ratio. These associations were more pronounced in men than in women.

CONCLUSION

Poor appetite, severe fatigue, low albumin level and a high CRP/albumin ratio were associated with increased mortality rates among patients with advanced cancer. All these variables might be clinically useful for prognostication in palliative cancer care.

TRIAL REGISTRATION

Clinicaltrial.gov. Identifier: NCT03038516;31, January 2017.

The metabolic interplay between dietary carbohydrate and exercise and its role in acute appetite regulation in males: a randomized controlled study

An understanding of the metabolic determinants of postexercise appetite regulation would facilitate development of adjunctive therapeutics to suppress compensatory eating behaviours and improve the efficacy of exercise as a weight-loss treatment. Metabolic responses to acute exercise are, however, dependent on pre-exercise nutritional practices, including carbohydrate intake. We therefore aimed to determine the interactive effects of dietary carbohydrate and exercise on plasma hormonal and metabolite responses and explore mediators of exercise-induced changes in appetite regulation across nutritional states. In this randomized crossover study, participants completed four 120 min visits: (i) control (water) followed by rest; (ii) control followed by exercise (30 min at ∼75% of maximal oxygen uptake); (iii) carbohydrate (75 g maltodextrin) followed by rest; and (iv) carbohydrate followed by exercise. An ad libitum meal was provided at the end of each 120 min visit, with blood sample collection and appetite assessment performed at predefined intervals. We found that dietary carbohydrate and exercise exerted independent effects on the hormones glucagon-like peptide 1 (carbohydrate, 16.8 pmol/L; exercise, 7.4 pmol/L), ghrelin (carbohydrate, -48.8 pmol/L; exercise: -22.7 pmol/L) and glucagon (carbohydrate, 9.8 ng/L; exercise, 8.2 ng/L) that were linked to the generation of distinct plasma 1 H nuclear magnetic resonance metabolic phenotypes. These metabolic responses were associated with changes in appetite and energy intake, and plasma acetate and succinate were subsequently identified as potential novel mediators of exercise-induced appetite and energy intake responses. In summary, dietary carbohydrate and exercise independently influence gastrointestinal hormones associated with appetite regulation. Future work is warranted to probe the mechanistic importance of plasma acetate and succinate in postexercise appetite regulation. KEY POINTS: Carbohydrate and exercise independently influence key appetite-regulating hormones. Temporal changes in postexercise appetite are linked to acetate, lactate and peptide YY. Postexercise energy intake is associated with glucagon-like peptide 1 and succinate levels.

A pecan-enriched diet reduced postprandial appetite intensity and enhanced peptide YY secretion: A randomized control trial

BACKGROUND & AIMS

Tree nuts have been shown to have satiating qualities; however, little is known concerning the effect of pecans on measures of appetite. The purpose of this study was to examine the impact of a pecan-enriched diet on subjective, physiological, and direct measures of appetite in older adults.

METHODS

This was a randomized, controlled trial in which healthy older adults (50-75 y) were randomized to either consume 68 g of pecans/day (pecan; n = 21) or avoid all nuts (control; n = 23) for 4 weeks. At pre- (V1) and post-diet (V2) visits body weight (BW) and body fat percentage (BF) were assessed and actual change in these outcomes for pecan were compared to theoretical changes if pecans were consumed without compensation. Subjective appetite was measured using visual analog scale (VAS), and blood was collected to assess changes in physiological appetite before and every 30 min for 4 h following a high-fat meal. Energy intake (EI) at a buffet meal was then assessed in the laboratory ("in-lab"). VAS assessments continued hourly for the next 7 h and EI ("at-home") was self-reported.

RESULTS

BW and BF did not change for pecan or control across the intervention and theoretical change in BW (theoretical: 2.2 ± 0.1 vs. actual: 0.4 ± 0.2 kg; p < 0.0001) and BF (theoretical: 0.4 ± 0.04 vs. actual: 0.2 ± 0.2%; p < 0.0001) was significantly greater than actual change for pecan. From V1 to V2, there was an increase in fasting (pecan: 77.0 ± 4.6 to 93.5 ± 6.1 vs control: 76.0 ± 5.0 to 72.5 ± 5.0 pg/mL; p = 0.01) and postprandial peptide YY for pecan vs. control (p = 0.04); however, fasting and postprandial cholecystokinin and ghrelin did not differ (p > 0.05). There were no differences in the change in subjective appetite ratings at fasting, following the high-fat meal (in-lab), at-home, or across the full day between groups (p > 0.05 for all). However, there was a significant suppression of peak desire to eat ratings for pecan vs. control (pecan: 67.9 ± 4.6 to 57.1 ± 5.2 vs. control: 61.9 ± 4.2 to 60.6 ± 4.3 mm; p = 0.04). Combined, buffet meal, and at-home EI did not differ significantly within pecan and control; however, there was a trend (p = 0.11) for a between group difference in buffet meal EI driven by increased EI for control (+137 ± 86 kcal) vs. decreased EI for pecan (-45 ± 77 kcal).

CONCLUSION

A 4-week pecan-enriched diet led to enhanced satietogenic metrics compared to a diet void of all nuts. As weight remained stable during the intervention, adding pecans to the daily diet may be beneficial to appetite control and weight maintenance in a healthy older population.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov: NCT04385537.

Ultraprocessed Foods and Obesity Risk: A Critical Review of Reported Mechanisms

Epidemiologic evidence supports a positive association between ultraprocessed food (UPF) consumption and body mass index. This has led to recommendations to avoid UPFs despite very limited evidence establishing causality. Many mechanisms have been proposed, and this review critically aimed to evaluate selected possibilities for specificity, clarity, and consistency related to food choice (i.e., low cost, shelf-life, food packaging, hyperpalatability, and stimulation of hunger/suppression of fullness); food composition (i.e., macronutrients, food texture, added sugar, fat and salt, energy density, low-calorie sweeteners, and additives); and digestive processes (i.e., oral processing/eating rate, gastric emptying time, gastrointestinal transit time, and microbiome). For some purported mechanisms (e.g., fiber content, texture, gastric emptying, and intestinal transit time), data directly contrasting the effects of UPF and non-UPF intake on the indices of appetite, food intake, and adiposity are available and do not support a unique contribution of UPFs. In other instances, data are not available (e.g., microbiome and food additives) or are insufficient (e.g., packaging, food cost, shelf-life, macronutrient intake, and appetite stimulation) to judge the benefits versus the risks of UPF avoidance. There are yet other evoked mechanisms in which the preponderance of evidence indicates ingredients in UPFs actually moderate body weight (e.g., low-calorie sweetener use for weight management; beverage consumption as it dilutes energy density; and higher fat content because it reduces glycemic responses). Because avoidance of UPFs holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, and food wastage), it is imprudent to make recommendations regarding their role in diets before causality and plausible mechanisms have been verified.

The effects of resistance exercise on appetite sensations, appetite related hormones and energy intake in hormone receptor-positive breast cancer survivors

Appetite is a determinant of dietary intake and is impacted by sex hormones, exercise, and body composition among individuals without chronic conditions. Whether appetite is altered by exercise in the context of estrogen suppression and cancer survivorship is unknown. This randomized cross-over study compared appetite and ad libitum energy intake (EI) after acute resistance exercise (REx) versus sedentary (SED) conditions and in relation to body composition and resting metabolic rate (RMR) in breast cancer survivors (BCS). Physically inactive premenopausal females with previous stage I-III estrogen receptor-positive breast cancer completed a single bout of REx or SED 35 minutes after a standardized breakfast meal. Appetite visual analog scales and hormones (total ghrelin and peptide-YY [PYY]) were measured before and 30, 90, 120, 150, and 180 minutes post-meal and expressed as area under the curve (AUC). Participants were offered a buffet-type meal 180 minutes after breakfast to assess ad libitum EI. Body composition (dual X-ray absorptiometry) and RMR (indirect calorimetry) were measured during a separate visit. Sixteen BCS were included (age: 46 ± 2 y, BMI: 24.9 ± 1.0 kg/m²). There were no differences in appetite ratings or EI between conditions. There were no differences in appetite hormone AUC, but REx resulted in lower ghrelin 120 (-85 ± 39 pg/mL, p = 0.031) and 180 (-114 ± 43 pg/mL, p = 0.018) minutes post-breakfast and higher PYY 90 (21 ± 10 pg/mL, p = 0.028) and 120 (14 ± 7 pg/mL, p = 0.041) minutes post-breakfast. Fat-free mass and RMR negatively correlated with hunger and prospective food consumption AUC after SED, but not REx. In sum, a single REx bout temporarily reduces orexigenic and increases anorexic appetite hormones, but not acute subjective appetite sensations or EI.

The effect of extracted and isolated fibers on appetite and energy intake: A comprehensive review of human intervention studies

In light of the increasing prevalence of obesity and cardiometabolic diseases, the underconsumption of fiber is concerning due to its various associated health benefits such as weight management. Adding extracted or isolated dietary fibers into various consumer products is a practical strategy for addressing the fiber gap. This comprehensive review identified evidence on the efficacy of different types of extracted and isolated fibers in reducing appetite and energy intake. Published reports of randomized controlled trials assessing appetite or energy intake in healthy adults were systematically searched, and those investigating extracted and isolated fibers following acute or chronic intake were selected. A total of 136 studies, consisting of 107 acute studies and 29 chronic studies, were included in the review. Overall, most fiber types did not show significant effects on appetite ratings and energy intakes. Acute intakes of two viscous fibers, alginate or guar gum, as well as oat fiber, were observed to most frequently result in reductions in appetite ratings. Additionally, chronic, but not acute, intakes of resistant maltodextrin/dextrin were also beneficial for appetite ratings. Viscous fibers were more likely to improve appetite ratings compared to non-viscous fibers, and fermentability did not appear to affect appetite ratings. Unfortunately, the current evidence base is highly varied due to the many differences in methodology and limited research on many of the fibers. While the possible benefits of extracted and isolated fibers on appetite sensations, food intake, and ultimately body weight regulation should not be completely dismissed, our review highlights the complexity of this research area and the gaps that need to be addressed to improve the robustness of the evidence.

Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity

Morning loaded calorie intake in humans has been advocated as a dietary strategy to improve weight loss. This is also supported by animal studies suggesting time of eating can prevent weight gain. However, the underlying mechanisms through which timing of eating could promote weight loss in humans are unclear. In a randomized crossover trial (NCT03305237), 30 subjects with obesity/overweight underwent two 4-week calorie-restricted but isoenergetic weight loss diets, with morning loaded or evening loaded calories (45%:35%:20% versus 20%:35%:45% calories at breakfast, lunch, and dinner, respectively). We demonstrate no differences in total daily energy expenditure or resting metabolic rate related to the timing of calorie distribution, and no difference in weight loss. Participants consuming the morning loaded diet reported significantly lower hunger. Thus, morning loaded intake (big breakfast) may assist with compliance to weight loss regime through a greater suppression of appetite.

Impact of starting BMI and degree of weight loss on changes in appetite-regulating hormones during diet-induced weight loss

OBJECTIVE

The aim of this study was to determine whether the hormone changes following weight loss are proportional to the degree of weight loss and to starting BMI.

METHODS

A very low-energy diet was used to achieve 15% weight loss. Fasting and postprandial gut hormones and leptin were measured during a meal test at baseline and at 5% (1%), 10% (2%), and 15% (2.5%) weight loss. Linear mixed-effects models were used to analyze hormone changes.

RESULTS

From baseline to 5% weight loss, decreases were seen in fasting concentrations of leptin (-8.25 ng/mL; p < 0.001), amylin (-21.3 pg/mL; p < 0.001), and glucagon-like peptide 1 (-59.55 pg/mL; p < 0.001). There was a small further reduction in leptin between 5% and 15% weight loss (-1.88 ng/mL; p = 0.019) but not in glucagon-like peptide 1 and amylin. Fasting ghrelin showed a significant increase at 10% weight loss (41.64 pg/mL; p = 0.002), with a nonsignificant increase from 10% to 15% loss (26.03 pg/mL; p = 0.065). Postprandial changes in hormone levels were variable. There was no correlation between baseline weight and the degree of hormone changes.

CONCLUSIONS

The majority of changes in fasting gut hormones and leptin occurred in early weight loss, with minor further changes up to 15% weight loss. Starting weight did not affect the degree of hormone change.

Predictive Validity of Image-Based Motivation-to-Eat Visual Analogue Scales in Normal Weight Children and Adolescents Aged 9-14 Years

Paper-based motivation-to-eat visual analogue scales (VASs) developed for adults are widely used in the pediatric age range. The VAS is comprised of four domains: hunger, fullness, desire to eat, and prospective food consumption. The purpose of the present study was to determine agreement between the traditional paper-based VAS and a novel digital VAS (with and without images), as well as the novel digital VAS's predictive validity for subsequent food intake (FI) in 9-14-year-old children and adolescents. Following an overnight fast and 3 h after consuming a standardized breakfast at home, children and adolescents (n = 17) completed three different VAS instruments (VAS_paper, VAS_images, VAS_no-images) in a randomized order at five time-points: 0 min (baseline), 5 min (immediately after consuming a 147 kcal yogurt treatment), 20 min, 35 min (immediately before an ad libitum lunch), and 65 min (immediately post ad libitum lunch). All three instruments were comparable, as shown by low bias and limits of agreement on Bland-Altman plots, moderate to excellent intraclass correlation coefficients for all domains at all time-points (ICC = 0.72-0.98), and no differences between the incremental area under the curve for any of the domains. All three instruments also showed good predictive validity for subsequent FI, with the strongest relationship observed immediately before the ad libitum lunch (p = 0.56-0.63). There was no significant association between subjective thirst and water intake, except with VAS_no-images at baseline (r = 0.49, p = 0.046). In conclusion, the present study suggests that a novel image-based digital VAS evaluating motivation-to-eat is interchangeable with the traditional paper-based VAS, and provides good predictive validity for next-meal FI in 9-14-year-old normal weight children and adolescents.

Homeostatic regulation of food intake

Food intake and energy expenditure are key regulators of body weight. To regulate food intake, the brain must integrate physiological signals and hedonic cues. The brain plays an essential role in modulating the appropriate responses to the continuous update of the body energy-status by the peripheral signals and the neuronal pathways that generate the gut-brain axis. This regulation encompasses various steps involved in food consumption, include satiation, satiety, and hunger. It is important to have a comprehensive understanding of the mechanisms that regulate food consumption as well as to standardize the vocabulary for the steps involved. This review discusses the current knowledge of the regulation and the contribution peripheral and central signals at each step of the cycle to control appetite. We also highlight how food intake has been measured. The increasingly complex understanding of regulation and action mechanisms intervening in the gut-brain axis offers ambitious targets for new strategies to control appetite.

A hypocaloric diet rich in high fiber rye foods causes greater reduction in body weight and body fat than a diet rich in refined wheat: A parallel randomized controlled trial in adults with overweight and obesity (the RyeWeight study)

BACKGROUND AND AIM

A high intake of whole grain foods is inversely associated with body mass index (BMI) and body fat in observational studies, but mixed results have been found in interventional studies. Among whole grains, rye is the richest source of dietary fiber and meals containing high-fiber rye foods have shown increased satiety up to 8 h, compared to meals containing refined wheat products. The aim of the study was to determine the effect of consuming high fiber rye products, compared to refined wheat products, on body weight and body fat loss in the context of an energy restricted diet.

METHODS

After a 2-week run-in period, 242 males and females with overweight or obesity (BMI 27-35 kg/m²), aged 30-70 years, were randomized (1:1) to consume high fiber rye products or refined wheat products for 12 weeks, while adhering to a hypocaloric diet. At week 0, week 6 and week 12 body weight and body composition (dual energy x-ray absorptiometry) was measured and fasting blood samples were collected. Subjective appetite was evaluated for 14 h at week 0, 6 and 12.

RESULTS

After 12 weeks the participants in the rye group had lost 1.08 kg body weight and 0.54% body fat more than the wheat group (95% confidence interval (CI): 0.36; 1.80, p < 0.01 and 0.05; 1.03, p = 0.03, respectively). C-reactive protein was 28% lower in the rye vs wheat group after 12 weeks of intervention (CI: 7; 53, p < 0.01). There were no consistent group differences on subjective appetite or on other cardiometabolic risk markers.

CONCLUSION

Consumption of high fiber rye products as part of a hypocaloric diet for 12 weeks caused a greater weight loss and body fat loss, as well as reduction in C-reactive protein, compared to refined wheat. The difference in weight loss could not be linked to differences in appetite response.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov, Identifier: NCT03097237.

Association of gastric emptying with postprandial appetite and satiety sensations in obesity

OBJECTIVE

Satiety, defined as the duration of the sensation of fullness, is usually measured by validated visual analog scales (VAS) for appetite. Gastric function plays a key role in food intake regulation. However, the association between gastric emptying (GE) and VAS appetite is unknown.

METHODS

In this cross-sectional study, 134 participants (mean [SEM] age = 39 [0.8] years, mean [SEM] BMI = 38 [0.5] kg/m² , 67% females) completed simultaneous measurements of GE and VAS appetite. After a 320-kcal meal, GE was measured by scintigraphy and appetite by validated 100-mm VAS for 240 minutes. Satiation was defined as calories consumed to terminate meal and was measured by an ad libitum meal. GE, VAS, and ad libitum meal tests were measured on the same day. Percent of meal retention in the stomach, VAS area under curve (AUC_{0-240 min} ), and overall appetite score (OAS) were calculated. Pearson correlation (ρ) determined the association of GE with VAS appetite and satiation. Appetite components were also analyzed by quartiles based on GE_{120 min} .

RESULTS

GE_{120 min} was correlated with sensation of VAS hunger_{AUC(0-240 min)} (ρ = 0.24, p = 0.004), fullness_{AUC(0-240 min)} (ρ = 0.16, p = 0.05), and OAS_{AUC(0-240 min)} (ρ = 0.20, p = 0.02). Patients with rapid GE_{120 min} had a mean increase in VAS hunger_{AUC(0-240 min)} by 32 mm/min (15.62%, p = 0.03) compared with normal/slow GE_{120 min} .

CONCLUSIONS

GE is associated with the sensations of appetite, and rapid GE is associated with increased appetite, which may contribute to weight gain.

Short-Term Protein Supplementation Does Not Alter Energy Intake, Macronutrient Intake and Appetite in 50-75 Year Old Adults

Ageing is associated with a reduction in muscle mass and strength, termed sarcopenia. Dietary protein is important for the maintenance of muscle mass through the promotion of muscle protein synthesis. However, protein is also reported to be a highly satiating nutrient. This raises concerns that protein intake for musculoskeletal health reasons in older adults may exacerbate age-related decreased appetite and may result in reduced energy and nutrient intake. This study aimed to investigate the effect of short-term protein supplementation and its timing (morning vs. evening), on energy and nutrient intake and appetite measures in middle-older age adults. Twenty-four 50-75 year olds were recruited to a randomised cross-over trial. In phase 1 (pre-supplementation) participants completed a food diary and reported hunger and appetite on three alternate days. During the second and third phases, participants consumed a 20 g whey protein gel (78 mL/368 kJ), for four days, either in the morning (after breakfast) or the evening (before bed), whilst completing the same assessments as phase 1. No differences in dietary intakes of energy, macronutrients and micronutrients were recorded when comparing the pre-supplementation phase to the protein supplementation phases, irrespective of timing (excluding the contribution of the protein supplement itself). Similarly, no differences were observed in self-reported feelings of hunger and appetite. In conclusion, a 20 g/day whey protein supplement given outside of meal-times did not alter habitual dietary intakes, hunger or appetite in this middle-older age adult population in the short-term. This approach may be a useful strategy to increasing habitual protein intake in the middle-older age population.

The influence of supraliminal priming on energy density of food selection: a randomised control trial

Background

Many people exercise because they know it is good for their health. Although this is true, it can make us feel deserving of a reward and lead us to eat more indulgent, less healthy food than if we had not done any exercise. Generally, lower energy-dense (LED) foods are recognised as healthier choices than higher energy-dense (HED) options. Despite our intention to make healthy choices, seeing tempting higher-calorie foods on offer often side-tracks us. Priming is a psychological tool that makes specific changes to our environment that remind us of our motivation to be healthy. This makes it easier to choose a healthier option, by nudging us towards it without us even realising. However, it is currently unclear which method of priming achieves the best results.

Aims

Our study explores whether priming people to expect they will receive LED food leads them to make this healthier choice after exercise, even when also offered tempting less healthy HED foods at the moment of selection.

Methods

Our study observed the foods selected by university athletes after their sports matches. Before the match, half of the participants were primed by asking them to choose a LED snack from the options we offered, which they would receive after the match. The remaining half of participants were not asked this same question. To distract the athletes from our observation of their food choices, participants completed a task prior to choosing their snack, which was disguised as a ‘thank you’ for taking part.

Results

Overall, we found the priming group did not choose LED foods significantly more than the control group, hence priming did not increase LED food selection.

Conclusion

Importantly, our results indicate that priming must be more noticeable to achieve its goal. Additionally, we demonstrated that priming may be less successful for young athletic individuals, compared to older and more overweight adults recruited in other studies. This highlights the importance of studying a broader demographic range of individuals from the general population. We support future research into this area, which will help us to tweak priming to achieve the best outcomes.

Trial registration

ISRCTN Registry, ISRCTN74601698. Date registered: 02/10/2020 (retrospectively registered).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-021-00554-1.

Exertional sodium loss does not increase immediate salt appetite or dietary sodium intake in athletes

We tested whether salt preference increases immediately after exertion-induced Na⁺ loss in sweat, and whether this may generalise to an increase in habitual dietary Na⁺ intake. For the first aim, trained athletes (n = 20) exercised in 2 ambient temperatures and sweat Na⁺ loss related to immediate salt preference assessed by taste, intake and psychophysical tests. For the second aim, we compared dietary and urinary Na⁺, and salt preference, seasoning and hedonics in the athletes and sedentary men (n = 20). No relationship was found between sodium loss during exercise and immediate preference for salt or psychophysical responses, and no differences in comparison to sedentary men. However, athlete diet had fewer foods (29.4 ± 1.5 vs 37.8 ± 1.9, p < 0.001), less seasoning (19 vs 32. p = 0.011) and more athletes reported dietary limitations (31 vs 11, p < 0.05), although nutrient content did not differ. Together these might suggest athlete adherence to a healthy diet at the expense of variety and flavour and a dissociation between dietary reports and intake. Athletes, more than controls, liked foods rich in energy and K⁺ suggesting compensatory-driven hedonics, although overall their intake did not differ. The findings are consistent with the absence of a salt appetite responding to Na⁺ loss in humans, and specifically that trained athletes do not increase their preference for salt in immediate response to exertion-induced Na⁺ loss and are not at risk for increased dietary Na⁺ compared to sedentary men.

Weight loss-induced increase in fasting ghrelin concentration is a predictor of weight regain: Evidence from the Diabetes Remission Clinical Trial (DiRECT)

AIM

To investigate whether appetite-related hormones were predictors of weight regain in the Diabetes Remission Clinical Trial (DiRECT).

MATERIALS AND METHODS

DiRECT is a cluster-randomized clinical trial, designed to assess the effect of weight loss on type 2 diabetes remission. For this post hoc analysis, data were available for 253 (147 interventions, 106 controls) individuals with type 2 diabetes (age 53.6 ± 7.5 years, body mass index 34.7 ± 4.4 kg/m2 , 59% men). Intervention participants received a 24-month weight management programme, and controls remained on usual diabetes care. Fasting plasma concentrations of leptin, ghrelin, glucagon-like peptide-1 and peptide YY were measured at baseline, 12 months and 24 months in all participants, and at 5 months in a subset of participants in the intervention (n = 56) and control groups (n = 22). Potential predictors were examined using multivariable linear regression models.

RESULTS

The intervention group lost 14.3 ± 6.0% body weight at 5 months but regained weight over time, with weight losses of 10.0 ± 7.5% at 12 months and 7.6 ± 6.3% at 24 months. Weight loss in controls was 1.1 ± 3.7% and 2.1 ± 5.0% at 12 and 24 months, respectively. Body weight increased by 2.3% (95% confidence interval [CI] 0.4, 4.1; P = 0.019) between 12 and 24 months for every 1-ng/mL increase in ghrelin between baseline and 12 months, and weight regain between 12 and 24 months was increased by 1.1% (95% CI 0.2, 2.0; P = 0.023) body weight for every 1-ng/mL increase in ghrelin at 12 months.

CONCLUSION

The rise in ghrelin (but not any other measured hormone) during diet-induced weight loss was a predictor of weight regain during follow-up, and concentrations remained elevated over time, suggesting a small but significant compensatory drive to regain weight. Attenuating the effects of ghrelin may improve weight-loss maintenance.

Circulating Metabolites Associated with Postprandial Satiety in Overweight/Obese Participants: The SATIN Study

Scope: To identify a metabolomic profile related to postprandial satiety sensations involved in appetite control would help for a better understanding of the regulation of food intake. Methods and Results: A cross-sectional analysis of plasma metabolites was conducted over 151 overweight/obese adults from the “Satiety Innovation”-SATIN study, a randomized clinical trial of a 12-week weight-loss maintenance period. Postprandial satiety sensations (3 h-iAUC) were assessed by visual analogue scale (VAS) at the beginning and at the end of the study. Fasting plasma metabolites were profiled using a targeted multiplatform metabolomics approach before each appetite test meal. Associations between 124 metabolites and iAUC-satiety were assessed using elastic net linear regression analyses. The accuracy of the multimetabolite weighted models for iAUC-VAS was evaluated using a 10-fold cross-validation (CV) approach and the Pearson’s correlation coefficients were estimated. Five and three metabolites were selected in the first and the second assessments, respectively. Circulating glycine and linoleic acid concentrations were consistently and positively associated with higher iAUC-satiety in both visits. Sucrose and sphingomyelins (C32:2, C38:1) were negatively associated with iAUC-satiety in the first visit. The Pearson correlations coefficients between the metabolomic profiles and iAUC-satiety in the first and the second appetite assessments were 0.37 and 0.27, respectively. Conclusion: Higher glycine and linoleic acid were moderately but consistently associated with higher postprandial satiety in two different appetite assessments in overweight and obese subjects.

Daily energy balance and eating behaviour during a 14-day cold weather expedition in Greenland

We assessed energy compensation, appetite, and reward value of foods during a 14-day military expedition in Greenland realized by 12 male French soldiers, during which energy compensation was optimized by providing them with easy-to-eat palatable foods in excess. Although daily energy expenditure (estimated by accelerometry) stayed relatively constant throughout the expedition (15 ± 9 MJ·day−1), energy intake (EI; estimated by self-reported diaries) was 17% higher during the D8–D14 period compared with the D1–D7 period, leading to a neutral energy balance (EB). Body fat mass (BFM) significantly decreased (–1.0 ± 0.7 kg, p < 0.001) but not body mass (BM). Neither hunger scores (assessed by visual analog scales) nor components of the reward value of food (explicit liking (EL) and food preference) were significantly altered. However, changes in EL at D10 were positively correlated with changes in BM (r = 0.600, p < 0.05) and BFM (r = 0.680, p < 0.05) and changes in hunger in the EI of the relevant period (r = 0.743, p < 0.01 for D1–D7, r = 0.652, p < 0.05 for D8–14). This study shows that the negative EB and BM loss can be attenuated by an appropriate food supply and that subjective components of eating behaviour, such as hunger and EL, may be useful to predict the magnitude of energy compensation.

Novelty Energy intake increases during of a 14-day expedition in the cold. Energy compensation was likely facilitated by providing participants with easy-to-eat palatable and familiar foods. Hunger scores and EL for energy-dense foods were associated with high EIs and low BM changes.

Very Low and Higher Carbohydrate Diets Promote Differential Appetite Responses in Adults with Type 2 Diabetes: A Randomized Trial

BACKGROUND

Effects of very low carbohydrate (VLC) diets on appetite response in individuals with type 2 diabetes remain unclear.

OBJECTIVE

A secondary analysis was conducted to determine appetite responses to an energy-restricted [30% of energy (%E) deficit] very low carbohydrate (VLC) diet compared with a higher carbohydrate (HC) diet in adults who were overweight or obese with type 2 diabetes.

METHODS

Forty-four men and 40 women (mean ± SD, age: 58.7 ± 6.6 y; weight: 100.4 ± 15.5 kg; BMI: 34.5 ± 4.1 kg/m2; glycated hemoglobin: 7.3 ± 1.0%; duration of diabetes: 6.7 ± 5.6 y) were randomly assigned to diets categorized as VLC [14%E carbohydrate (<50 g/d), 28%E protein, 58%E fat (<10%E saturated fat)], or energy-matched HC [53%E carbohydrate, 17%E protein, 30%E fat (<10%E saturated fat)] combined with progressive multicomponent exercise (60 min; 3 d/wk). Body weight, average weekly "daily fasting" and "daily overall" appetite perceptions (hunger, fullness, prospective consumption, and desire to eat-visual analog scales) were assessed at baseline and after 4 and 16 wk. Changes between diets over time were assessed using repeated measures ANOVA.

RESULTS

Significant decreases in body weight did not differ between groups (VLC: -11.0 ± 5.4 kg/16 wk compared with HC: -10.1 ± 4.3 kg/16 wk, P = 0.40). Compared with HC, VLC had greater decreases in "daily overall" ratings of fullness (P time × diet < 0.01), such that scores were higher in HC at Week 4 (VLC:48 ± 3 vs HC:56 ± 3 mm, P = 0.001) and 16 (VLC:51 ± 2 vs HC:57 ± 3 mm, P = 0.019). Compared with HC, VLC had greater increases in prospective consumption ratings (P time × diet = 0.03), such that scores were lower in HC at Week 4 (VLC:33 ± 2 vs HC:28 ± 2 mm, P = 0.008), but not at Week 16 (VLC:33 ± 2 vs HC 31 ± 2 mm, P = 0.289).

CONCLUSIONS

In the context of energy restriction, both HC and VLC energy-matched diets promoted comparable effects on fasting perceptions of appetite, but the HC diet resulted in greater "daily overall" fullness and reduced prospective consumption. Further research is required to evaluate the effects of ad libitum diets differing in amounts of carbohydrate on appetite response in populations with type 2 diabetes. This trial was registered at www.anzctr.org.au as ACTRN12612000369820.

The role of appetite-related hormones, adaptive thermogenesis, perceived hunger and stress in long-term weight-loss maintenance: a mixed-methods study

BACKGROUND/OBJECTIVES

Weight-loss maintenance is challenging, and few succeed in the long term. This study aimed to explain how appetite-related hormones, adaptive thermogenesis, perceived hunger and stress influence weight-loss maintenance.

SUBJECTS/METHODS

Fifteen adult women (age, 46.3 ± 9.5 years; BMI, 39.4 ± 4.3 kg/m²) participated in a 24-month intervention, which included 3-5 months total diet replacement (825-853 kcal/d). Body weight and composition (Magnetic Resonance Imaging), resting metabolic rate (indirect calorimetry), and fasting plasma concentration of leptin, ghrelin, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and growth differentiation factor 15 (GDF-15) were measured at baseline and after weight loss, around 6 months. Perceptions relating to weight-loss maintenance were explored using qualitative interviews.

RESULTS

Mean (SD) changes in body weight (-13.8 ± 6.3 kg) and total adipose tissue (-11.5 ± 4.9 kg) were significant (P < 0.001). Weight loss was associated with a significant reduction in resting metabolic rate (-291 ± 226 kcal/day, P < 0.001) and adaptive thermogenesis (-150 ± 162 kcal/day, P = 0.003), reduction in leptin (P < 0.001) and GLP-1 (P = 0.015), an increase in ghrelin (P < 0.001), and no changes in PYY and GDF-15. Weight regain between 6 and 24 months (6.1 ± 6.3 kg, P < 0.05) was negatively correlated with GLP-1 at baseline (r = −0.7, P = 0.003) and after weight loss (r = -0.7, P = 0.005). Participants did not report increased hunger after weight loss, and stress-related/emotional eating was perceived as the main reason for regain.

CONCLUSIONS

Weight regain is more likely with lower fasting GLP-1 at baseline and following weight loss, but psychological aspects of eating behaviour appear as important in attenuating weight-loss maintenance.

Pre-Sleep Casein Protein Ingestion Does Not Impact Next-Day Appetite, Energy Intake and Metabolism in Older Individuals

Maintaining adequate daily protein intake is important to maintain muscle mass throughout the lifespan. In this regard, the overnight period has been identified as a window of opportunity to increase protein intake in the elderly. However, it is unknown whether pre-sleep protein intake affects next-morning appetite and, consequently, protein intake. Therefore, the purpose of the current study was to investigate the effects of a pre-sleep protein drink on next-morning appetite, energy intake and metabolism. Twelve older individuals (eight males, four females; age: 71.3 ± 4.2 years) took part in a single-blind randomised cross-over study. After a standardised dinner, participants consumed either a 40-g protein drink, isocaloric maltodextrin drink, or placebo water control before bedtime. Next-morning appetite, energy intake, resting metabolic rate (RMR), respiratory exchange rate (RER), and plasma acylated ghrelin, leptin, glucose, and insulin concentrations were assessed. No between-group differences were observed for appetite and energy intake at breakfast. Furthermore, RMR, RER, and assessed blood markers were not significantly different between any of the treatment groups. Pre-sleep protein intake does not affect next-morning appetite and energy intake and is therefore a viable strategy to increase daily protein intake in an older population.

Is reduction in appetite beneficial for body weight management in the context of overweight and obesity? Yes, according to the SATIN (Satiety Innovation) study

New dietary-based concepts are needed for treatment and effective prevention of overweight and obesity. The primary objective was to investigate if reduction in appetite is associated with improved weight loss maintenance. This cohort study was nested within the European Commission project Satiety Innovation (SATIN). Participants achieving ≥8% weight loss during an initial 8-week low-energy formula diet were included in a 12-week randomised double-blind parallel weight loss maintenance intervention. The intervention included food products designed to reduce appetite or matching controls along with instructions to follow national dietary guidelines. Appetite was assessed by ad libitum energy intake and self-reported appetite evaluations using visual analogue scales during standardised appetite probe days. These were evaluated at the first day of the maintenance period compared with baseline (acute effects after a single exposure of intervention products) and post-maintenance compared with baseline (sustained effects after repeated exposures of intervention products) regardless of randomisation. A total of 181 participants (forty-seven men and 134 women) completed the study. Sustained reduction in 24-h energy intake was associated with improved weight loss maintenance (R 0·37; P = 0·001), whereas the association was not found acutely (P = 0·91). Suppression in self-reported appetite was associated with improved weight loss maintenance both acutely (R −0·32; P = 0·033) and sustained (R −0·33; P = 0·042). Reduction in appetite seems to be associated with improved body weight management, making appetite-reducing food products an interesting strategy for dietary-based concepts.

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.

Is reducing appetite beneficial for body weight management in the context of overweight and obesity? A systematic review and meta-analysis from clinical trials assessing body weight management after exposure to satiety enhancing and/or hunger reducing products

This review aims to investigate whether interventions that enhance satiety and/or reduce hunger lead to beneficial effects on body weight management in the context of overweight and obesity. A comprehensive review protocol was prepared before conducting a systematic search in PubMed identifying 517 papers with 12 meeting the inclusion criteria. A thorough risk of bias assessment was performed based on the Cochrane collaboration's tool for assessing risk of bias. Based on a meta-analysis, the average of 75 subjects exposed to satiety enhancing and/or hunger reducing foods during more than 8 weeks coincidently reduced their body weight by 3.60 (1.05; 6.15) kg (mean (95% confidence interval)) more compared with controls. Two studies analysed whether individual reductions in appetite were associated with body weight. Decreased ad libitum energy intake after exposure to the satiety enhancing and/or hunger reducing interventions explained 58% (P < 0.001) and 23% (P < 0.001) of the variations in the subsequent weight losses over 12 and 8 weeks, respectively. Robust acute effects on appetite were found equally likely to be linked to improved body weight management as sustained effects. Satiety enhancing and/or hunger reducing interventions are supported to improve body weight management, but studies specifically designed to demonstrate a causal link remain needed.

Food Type and Lentil Variety Affect Satiety Responses but Not Food Intake in Healthy Adults When Lentils Are Substituted for Commonly Consumed Carbohydrates

BACKGROUND

Lentils have potential to increase satiety and may contribute to a body weight management strategy; however, the effects on satiety of replacing common food ingredients with lentils within food products remain largely unknown.

OBJECTIVE

The aim of this study was to determine the effects of replacing wheat and rice with 2 lentil varieties within muffins and chilies on satiety, test-meal food intake, and 24-h energy intake.

METHODS

Healthy adults consumed muffins or chilies in which wheat or rice was substituted with green (61.8 g) or red (54 g) lentils in 2 randomized crossover studies (muffin study: n = 24, mean ± SE age: 25.4 ± 0.9 y, BMI (in kg/m2): 23.2 ± 0.5; chili study: n = 24, age: 25.7 ± 1.0 y, BMI: 23.2 ± 0.5), with ≥1-wk washout periods between study visits and studies. Subjective appetite sensations measured over 180 min were summarized with total area under the curve (AUC), food intake was measured at an ad libitum test meal, and 24-h energy intake was measured using weighed food records. Treatment effects were compared within each study using repeated-measures ANCOVA (subjective appetite sensations) and ANOVA (food intake, 24-h energy intake).

RESULTS

Green, but not red, lentil chili significantly increased fullness AUC (17.5%, P = 0.02) and decreased desire to eat AUC (20.1%, P = 0.02) and prospective food consumption AUC (16.7%, P = 0.04) compared with rice chili, with no significant differences between chili treatments for test-meal food intake or 24-h energy intake. Muffin treatments did not significantly differ for any outcomes.

CONCLUSIONS

Replacing rice with green, but not red lentils within chili increases satiety but does not decrease food intake, whereas replacing wheat with lentils within muffins does not increase satiety or decrease food intake in healthy adults. Further study of the role of lentil replacement in food products in body weight management is warranted. This trial was registered at clinicaltrials.gov as NCT03128684.

Novel Methodological Considerations Regarding the Use of Visual Analog Scale (VAS) Appetite Questionnaires in Tightly Controlled Feeding Trials

Visual analog scale (VAS) questionnaires are widely used in nutrition research to assess appetite and subsequent food intake. However, a number of methodological considerations exist. The study aims were to test whether 1) appetite VASs alter subsequent food intake and 2) viewing previous appetite responses influences subsequent responses. Twelve healthy adults (age: 22 ± 3 y; BMI: 22.0 ± 3.1 kg/m2) completed the randomized crossover study. On separate days, participants were provided breakfast preloads and completed appetite VASs every 30 min for 4 h or did not complete the questionnaires. When completing VASs, the participants were shown their previous responses (PR) or were not (No-PR). After 4 h, an ad libitum lunch was provided. Hunger, fullness, desire to eat, and prospective food consumption were not different between PR and No-PR. All data are reported as mean ± SEM. VASs did not affect lunch intake (484 ± 50 kcal) compared with no VASs (500 ± 53 kcal, nonsignificant). Thus, neither past appetite responses nor the use of appetite VASs influenced ingestive behavior in healthy adults. This trial was part of a larger acute, randomized crossover trial registered at clinicaltrials.gov as NCT03154606.

Habitual Breakfast Patterns Do Not Influence Appetite and Satiety Responses in Normal vs. High-Protein Breakfasts in Overweight Adolescent Girls

Differences in postprandial insulin, glucose, and/or free fatty acid concentrations, following the consumption of breakfast, have been demonstrated to be dependent on habitual breakfast patterns. This study examined the effects of habitual breakfast patterns on postprandial appetite, satiety, and hormonal responses along with daily food intake following the consumption of normal-protein (NP) vs. higher-protein (HP) breakfasts in overweight adolescents. Thirty-seven girls (age: 19 ± 1 year; BMI: 29.0 ± 3.4 kg/m²) participated in the semi-randomized crossover design study. Participants were grouped according to whether they habitually skipped (SKIP, n = 18) or consumed breakfast (CONSUME, n = 19), and consumed a NP (350 kcal; 13 g protein) or HP (350 kcal; 35 g protein) breakfast for 3 days/pattern. On day 4, breakfast was provided, and appetite questionnaires and blood samples were collected throughout an 8 h testing day. Daily food intake was also assessed. Regardless of habitual breakfast patterns, the consumption of HP breakfast led to greater daily fullness (29,030 ± 6,010 min × mm) vs. NP breakfast (26,910 ± 5580 min × mm; p = 0.03). Daily protein consumption was greater (98 ± 15 g vs. 78 ± 15 g), and carbohydrate consumption was lower (331 ± 98 g vs. 367 ± 94 g) with HP vs. NP (both, p < 0.001). No other differences were observed. These data suggest that the recommendation to consume a HP breakfast for improved satiety and ingestive behavior is appropriate for overweight adolescent girls, regardless of habitual breakfast patterns.

Influence of rice, pea and oat proteins in attenuating glycemic response of sugar-sweetened beverages

PURPOSE

Liquids have higher ingestion and gastric-emptying rates, resulting in rapid glycemic response. They are also less satiating than solid foods. This study examined if the addition of plant proteins alter postprandial glucose, insulin, triglycerides, glucose-dependent insulinotropic peptide (GIP), glycogen-like peptide-1 (GLP-1) and appetitive responses to a sugar-sweetened beverage.

METHODS

This was a randomized, crossover acute feeding study consisting of four treatments: chocolate beverage alone (50 g carbohydrate), or added with 24 g oat, pea or rice proteins. Twenty Chinese males (mean ± SD age 26 ± 5 years; body mass index 21.5 ± 1.7 kg/m2) ingested the test drink after an overnight fast. Venous blood samples and subjective appetite ratings were collected before test beverage and at fixed intervals for 180 min. Blood biochemical data and appetite ratings were compared using repeated-measures ANOVA.

RESULTS

Significant interaction effects were found in postprandial glucose excursions (time × protein effects, p = 0.003). Glucose iAUC was lower in pea and rice proteins, although not significantly (p > 0.385). Insulin iAUC was significantly higher in the oat (p = 0.035) and pea (p = 0.036) protein beverages. GIP and GLP-1 release in a sub-sample (n = 10) followed a comparable order as insulin release (p = 0.397 and 0.454, respectively). Significant interaction effects were found in fullness ratings (p = 0.024), and a trend of greater suppression of hunger and desire-to-eat was also documented (p = 0.088 and 0.080, respectively).

CONCLUSIONS

Plant proteins altered the glycemic and appetitive responses of Asian males to a sugar-sweetened beverage. Food-based interventions are useful in promoting glycemic control. This trial was registered with ClinicalTrials.gov as NCT02933424.

Impact of weight loss achieved through a multidisciplinary intervention on appetite in patients with severe obesity

The impact of lifestyle-induced weight loss (WL) on appetite in patients with obesity remains controversial. This study aimed to assess the short- and long-term impact of WL achieved by diet and exercise on appetite in patients with obesity. Thirty-five (22 females) adults with severe obesity (body mass index: 42.5 ± 5.0 kg/m²) underwent a 2-yr WL program focusing on diet and exercise. Body weight (BW), cardiovascular fitness (V̇o_2max), appetite feelings, and plasma concentrations of insulin, active ghrelin (AG), glucagon-like peptide 1 (GLP-1), peptide YY (PYY), and cholecystokinin (CCK), in the fasting and postprandial states, were measured at baseline (B), week 4 (W4), and 1 and 2 yr (and average values for all fasting and postprandial time points computed). BW was significantly reduced and V̇o_2max (ml·kg^-1·min^-1) increased at all time points compared with B (3.5, 8.1, and 8.4% WL and 7, 11, and 8% increase at W4 and 1 and 2 yr, respectively). Basal hunger and average hunger and desire to eat were significantly increased at 1 and 2 yr. Basal fullness was significantly increased at W4, and average ratings were reduced at 1 yr. Average AG and PYY were significantly increased, and insulin was reduced, at all time points compared with B. Average GLP-1 was reduced at W4, and CCK was increased at 2 yr. After lifestyle-induced WL, patients with severe obesity will, therefore, have to deal with increased hunger in the long term. In conclusion, sustained WL at 2 yr achieved with diet and exercise is associated with increased hunger feelings and ghrelin concentration but also increased postprandial concentrations of satiety hormones.

Subjective feelings of appetite of wholegrain breakfasts evaluated under controlled, laboratory and 'at home' conditions

BACKGROUND

Appetite regulating properties of foods are usually investigated under laboratory conditions, whereas in real life, foods are consumed under at home conditions. The objective of this study was to compare the acute effects of breakfasts when tested in a laboratory condition and in an at home condition. Appetite regulating properties of two bread breakfasts and two cereal breakfasts were also compared.

SUBJECTS AND METHODS

In this randomized cross-over trial balanced for laboratory and at home test conditions, thirty-two women consumed five breakfasts, i.e. two bread breakfasts, two cereal breakfasts and one fried-egg breakfast. Visual analogue scales for measuring appetite were captured via an on-line scoring system and were analyzed as incremental area under the curve, as satiation phase and as satiety phase.

RESULTS

Location effects were limited to two small effects only. An overall location effect in hunger feelings was observed (p = 0.040), which occurred specifically during the short satiation period (p = 0.0002) where hunger feelings scored higher under laboratory conditions. Similarly, a location effect was observed for desire to eat (p = 0.001); this was again higher under laboratory conditions. No other location effects were observed. Bread breakfasts did not differ in their appetite regulating properties. The Steel Cut oatmeal breakfast was reported to be more satiating (p = 0.001) as compared to the ready-to-eat cereal.

CONCLUSIONS

Whereas the five breakfasts varied somewhat in their appetite regulating properties, evaluation under laboratory conditions overall did not result in different appetite scores compared to the at home conditions. This suggests that at home testing may be a useful alternative to laboratory test conditions for nutrition research.

Protein for Life: Review of Optimal Protein Intake, Sustainable Dietary Sources and the Effect on Appetite in Ageing Adults

With an ageing population, dietary approaches to promote health and independence later in life are needed. In part, this can be achieved by maintaining muscle mass and strength as people age. New evidence suggests that current dietary recommendations for protein intake may be insufficient to achieve this goal and that individuals might benefit by increasing their intake and frequency of consumption of high-quality protein. However, the environmental effects of increasing animal-protein production are a concern, and alternative, more sustainable protein sources should be considered. Protein is known to be more satiating than other macronutrients, and it is unclear whether diets high in plant proteins affect the appetite of older adults as they should be recommended for individuals at risk of malnutrition. The review considers the protein needs of an ageing population (>40 years old), sustainable protein sources, appetite-related implications of diets high in plant proteins, and related areas for future research.

Mechanisms responsible for homeostatic appetite control: theoretical advances and practical implications

Homeostatic appetite control is part of a psychobiological system that has evolved to maintain an adequate supply of nutrients for growth and maintenance. The system links the physiological needs for energy with the behaviour that satisfies these needs (feeding), and is shaped by excitatory and inhibitory signals. Owing to rapid shifts in the food environment, homeostatic appetite control is not well adapted for modern-day human functioning. Areas covered: Homeostatic appetite control has two divisions. Tonic processes exert stable and enduring influences, with signals arising from bodily tissues and metabolism. Episodic processes fluctuate rapidly and are related to nutrient ingestion and the composition of foods consumed. Research in these areas incorporates potent endocrine signals that can influence behaviour. Expert commentary: The regulation of adipose tissue, and its impact on appetite (energy) homeostasis, has been heavily researched. More recently however, it has been demonstrated that fat-free mass has the potential to act as a tonic driver of food intake. A challenging issue is to determine how the post-prandial action of episodic satiety hormones and gastrointestinal mechanisms can effectively brake the metabolic drive to eat, in order to keep food intake under control and prevent a positive energy balance and fat accumulation.

Cross-sectional and longitudinal associations between different exercise types and food cravings in free-living healthy young adults

INTRODUCTION

An increase in energy intake due to alterations in hedonic appetite sensations may, at least in part, contribute to lower-than-expected weight loss in exercise interventions. The aim of this study was to examine cross-sectional and longitudinal associations between habitual exercise participation and food cravings in free-living young adults.

METHODS

A total of 417 adults (49% male, 28 ± 4 years) reported frequency and duration of walking, aerobic exercise, resistance exercise and other exercise at baseline and every 3 months over a 12-month period. Food cravings were assessed via the Control of Eating Questionnaire at baseline and 12-month follow-up.

RESULTS

Cross-sectional analyses revealed more frequent cravings for chocolate and a greater difficulty to resist food cravings in women compared to men (p < 0.01). Only with resistance exercise significant sex by exercise interaction effects were observed with favorable responses in men but not in women. Significant main effects were shown for walking and aerobic exercise with exercisers reporting more frequent food cravings for chocolate and fruits and greater difficulty to resist eating compared to non-exercisers (p < 0.05). Longitudinal analyses revealed significant interaction effects for other exercise (p < 0.05) with favorable results in men but not women. Furthermore, significant main effects were observed for aerobic exercise, resistance exercise and total exercise with an increase in exercise being associated with a reduced difficulty to resist food cravings (p < 0.05).

DISCUSSION

The association between exercise participation and hedonic appetite sensations varies by exercise type and sex. Even though exercise was associated with more frequent and greater difficulty to food cravings in the cross-sectional analyses, which may be attributed to greater energy demands, longitudinal results indicate beneficial effects of increased exercise on appetite control, particularly in men.

Reducing Calorie Intake May Not Help You Lose Body Weight

As the widespread availability of highly calorific food has resulted in a high incidence of obesity, attempts to decrease body weight have concentrated on trying to reduce energy intake. It is suggested that this is not the best approach. Although consuming more calories than expended is part of the initial problem, it does not follow that reducing intake, unless consciously counting calories, is the best solution. Mechanisms smooth out the large day-to-day differences in energy consumption, decreasing the importance of the size of a meal. In the short term a reduction in energy intake is counteracted by mechanisms that reduce metabolic rate and increase calorie intake, ensuring the regaining of lost weight. For example, even a year after dieting, hormonal mechanisms that stimulate appetite are raised. Over a million calories are consumed a year yet weight changes to only a small extent; there must be mechanisms that balance energy intake and expenditure. As obesity reflects only a small malfunctioning of these mechanisms, there is a need to understand the control of energy balance and how to prevent the regaining of weight after it has been lost. By itself, decreasing calorie intake will have a limited short-term influence.

Timeline of changes in appetite during weight loss with a ketogenic diet

Background/objective:

Diet-induced weight loss (WL) leads to increased hunger and reduced fullness feelings, increased ghrelin and reduced satiety peptides concentration (glucagon-like peptide-1 (GLP-1), cholecystokinin (CCK) and peptide YY (PYY)). Ketogenic diets seem to minimise or supress some of these responses. The aim of this study was to determine the timeline over which changes in appetite occur during progressive WL with a ketogenic very-low-energy diet (VLED).

Subjects/methods:

Thirty-one sedentary adults (18 men), with obesity (body mass index: 37±4.5 kg m⁻²) underwent 8 weeks (wks) of a VLED followed by 4 wks of weight maintenance. Body weight and composition, subjective feelings of appetite and appetite-related hormones (insulin, active ghrelin (AG), active GLP-1, total PYY and CCK) were measured in fasting and postprandially, at baseline, on day 3 of the diet, 5 and 10% WL, and at wks 9 and 13. Data are shown as mean±s.d.

Results:

A significant increase in fasting hunger was observed by day 3 (2±1% WL), (P<0.01), 5% WL (12±8 days) (P<0.05) and wk 13 (17±2% WL) (P<0.05). Increased desire to eat was observed by day 3 (P<0.01) and 5% WL (P<0.05). Postprandial prospective food consumption was significantly reduced at wk 9 (16±2% WL) (P<0.01). Basal total PYY was significantly reduced at 10% WL (32±8 days) (P<0.05). Postprandial active GLP-1 was increased at 5% WL (P<0.01) and CCK reduced at 5 and 10% WL (P<0.01, for both) and wk 9 (P<0.001). Basal and postprandial AG were significantly increased at wk 13 (P<0.001, both).

Conclusions:

WL with a ketogenic VLED transiently increases the drive to eat up to 3 weeks (5% WL). After that, and while participants are ketotic, a 10–17% WL is not associated with increased appetite. However, hunger feelings and AG concentrations increase significantly from baseline, once refeeding occurs.

The Differential Role of Smell and Taste For Eating Behavior

Food choice and food intake are guided by both sensory and metabolic processes. The senses of taste and smell play a key role in the sensory effects on choice and intake. This article provides a comprehensive overview of, and will argue for, the differential role of smell and taste for eating behavior by focusing on appetite, choice, intake, and satiation. The sense of smell mainly plays a priming role in eating behavior. It has been demonstrated that (orthonasal) odor exposure induces appetite specifically for the cued food. However, the influence of odors on food choice and intake is less clear, and may also depend on awareness or intensity of the odors, or personality traits of the participants. Taste on the other hand, has a clear role as a (macro)nutrient sensing system, during consumption. Together with texture, taste is responsible for eating rate, and thus in determining the oral exposure duration of food in the mouth, thereby contributing to satiation. Results from these experimental studies should be taken to real-life situations, to assess longer-term effects on energy intake. With this knowledge, it will be possible to steer people's eating behavior, as well as food product development, toward a less obesogenic society.