Influence of BMI and gender on postprandial hormone responses

Effect of 100% Orange Juice and a Volume-Matched Sugar-Sweetened Drink on Subjective Appetite, Food Intake, and Glycemic Response in Adults

Dietary recommendations to reduce the consumption of free sugars often group 100% fruit juice with other sugar-containing beverages. The objective of this study was to determine the effect of consuming 100% orange juice compared to an orange drink on next-meal food intake (FI), glycemic response, average appetite, emotions, and sensory characteristics in normal-weight adults. Thirty-six normal-weight adults (age: 26.8 ± 0.9 years) consumed, in random order and at least 5 days apart, three 240 mL test beverages as follows: (a) 100% orange juice, (b) orange drink, or (c) water. Subjective sweetness and pleasantness were determined immediately after test beverage consumption. Glycemic response, average appetite, and subjective emotions were measured every 15 min for 60 min. Food intake was determined at a pizza lunch 60 min later. Rest-of-day glycemic response and energy intake (EI) were determined using a continuous glucose monitor and food record, respectively. Lunch FI (p = 0.054) and total EI (p = 0.01) were both lower after 100% orange juice compared with the orange drink. Caloric compensation was 84% after 100% orange juice and -25% after the orange drink (p = 0.047). Average appetite was not significantly different between the test beverages (p > 0.05). Blood glucose iAUC adjusted for available carbohydrate was lower after 100% orange juice compared with the orange drink (p < 0.001). Rest-of-day blood glucose concentrations were lower after 100% orange juice compared with the orange drink (p = 0.03) and water control (p < 0.001). In conclusion, consumption of 100% orange juice as a preload resulted in higher caloric compensation, lower total daily EI, and lower blood glucose concentrations compared to the orange drink.

Trends in Obesity-Related Mortality and Racial Disparities

BACKGROUND

Across the globe, obesity stands as a prominent public health concern, linked to a heightened susceptibility to a range of metabolic and cardiovascular disorders. This study reveals a disproportionate impact of obesity on African American (AA) communities, irrespective of socioeconomic status. Structural racism plays a critical role in perpetuating healthcare disparities between AA and other racial/ethnic groups in the United States. These disparities are reflected in limited access to nutritious food, safe exercise spaces, health insurance, and medical care, all of which significantly influence healthcare outcomes and obesity prevalence. Additionally, both conscious and unconscious interpersonal racism adversely affect obesity care, outcomes, and patient-healthcare provider interactions among Blacks.

STUDY OBJECTIVE

This study aims to analyze and compare obesity-related mortality rates among AAs, Whites, and other racial groups.

METHODOLOGY

We queried the CDC WONDER dataset, incorporating all US death certificates. During data extraction, various ICD 10 codes were used to denote different obesity categories: E66.1 (drug-induced obesity), E66.2 (severe obesity with alveolar hypoventilation), E66.3 (overweight), E66.8 (other forms of obesity), E66.9 (unspecified obesity), E66.0 (obesity due to excess calorie intake), E66.01 (severe obesity due to excess calories), and E66.09 (other forms of obesity caused by excess calorie intake). Our study encompassed decedents aged ≥15 years, with obesity-related diseases as the underlying cause of death from 2018 to 2021. Sex- and race-specific obesity-related mortality rates were examined for AAs, Whites, and other races. Resultant mortality trends were computed and presented as ratios comparing AA and White populations.

RESULTS

This study reveals lower obesity-related mortality rates in AAs compared to Whites. Furthermore, women exhibited higher rates than men. In the 15 to 24 age bracket, males comprised 60.11% of the 361 deaths, whereas females made up 39.89%. In this demographic, 35.46% of deaths were among Blacks, with 64.54% among Whites. Within the 25 to 34 age group, females constituted 37.26% of the 1943 deaths, and males 62.74%. Whites made up 62.94% of the fatalities, Blacks 33.40%, with other racial groups accounting for the remainder. These trends extended through the 35-44, 45-54, 55-64, 65-74, and 75+ age categories, with variations in death proportions among genders and races. Whites consistently accounted for the highest death percentages across all age groups, followed by Blacks. Our data indicate that obesity-related mortality tends to occur earlier in life.

CONCLUSION

Our results corroborate previous studies linking elevated mortality risk to obesity and overweight conditions. The uniformity of our findings across age groups, as well as genders, supports the proposal for applying a single range of body weight throughout life. Given the ongoing rise in obesity and overweight conditions across the United States, excess mortality rates are projected to accelerate, potentially leading to decreased life expectancy. This highlights the urgency for developing and implementing effective strategies to control and prevent obesity nationwide.

Potential contributors to variation in weight-loss response to liraglutide

Obesity treatment requires a chronic state of negative energy balance. Obesity medications can help with this, increasing long-term dietary compliance by promoting satiety or reducing hunger. However, efficacy and safety of obesity medications vary for individuals. Early identification of non-responders to obesity medications may limit drug exposure while optimizing benefits for responders. This review summarizes factors that impact weight-loss response to liraglutide. Factors linked to greater weight loss on liraglutide include being female, not having diabetes, having relatively high baseline weight, and losing at least 4% of initial weight after 16 weeks of treatment. Other covariates that may predict treatment response but require further confirmation include central effects, nausea, gastric emptying of solids, and genotype. Baseline body mass index, race, and age seem less relevant for predicting weight-loss response to liraglutide. Lesser known and harder-to-measure factors such as cerebral blood flow, food cue reactivity, gut hormone levels, and dietary adherence possibly impact variability of response to liraglutide. This information should assist healthcare providers with establishing realistic weight-loss probability for individual patients. Future research should improve the ability to identify responders to liraglutide. Importantly, this review may provide a framework to identify responders to other obesity medications.

The effects of early short-term insulin treatment vs. glimepiride on beta cell function in newly diagnosed type 2 diabetes with HbA1c above 9

BACKGROUND

Type 2 diabetes mellitus (T2D) is a complex metabolic impairment. Beta cell (BC) failure is the most challenging among its pathogenetic mechanisms. Recognizing reversible contributors to BC failure could guide individualized approach to early T2D treatment. The aim of this study was to compare early short-term insulin treatment vs. glimepiride, both added to metformin, on BC function, glycemic and lipid control, during 12-month follow-up.

METHODS

Eighty newly diagnosed T2D patients, 30-65 years of age, presenting with HbA1c ≥ 9% were enrolled in the study. They were randomly assigned to single-month initial insulin therapy (INS) added to metformin, or to glimepiride and metformin (OAD) as only treatment. Subjects assigned to initial insulin intervention were thereafter switched to OAD. C-peptide (C-Pep) was analyzed at baseline and 2 hours after standardized test meal (STM). All subjects were STM-retested after 3 and 12 months. HbA1c, serum lipids, BMI, HOMA IR, and HOMA B were assessed over follow-up.

RESULTS

HbA1c was lower in INS vs OAD at 3-months: 6.26 ± 0.18% vs 6.78 ± 0.10% (p = 0.016), remaining so by 12 months (p =0.056). BMI-adjusted ΔC-Pep was greater in INS vs. OAD at 3 months (4.60 ± 0.59 vs. 3.21 ± 0.34 m2 /kg; p = 0.044), persisting by 12months (4.57 ± 0.56 vs. 3.04 ± 0.34 m2/kg; p = 0.023). Average ΔC-Pep improvement from recruitment to 3 months was 100.8% in INS,vs. 51.3% in OAD. Prevalence of STM-ΔC-Pep response greater than 2.4 ng/mL had risen 3.2-fold by 12 months in the INS, vs. 2.4-fold only in the OAD group (p = 0.018).

DISCUSSION

Early short-term insulin intervention in newly diagnosed T2D improves beta cell function more than glimepiride, both added to metformin, resulting in a superior and longer lasting glycemic and lipid control.

Prospective Cohort of Pre- and Post-Diagnosis Diet with Survival Outcomes: an Alberta Endometrial Cancer Cohort Study

BACKGROUND

The prognostic relationship between diet and endometrial cancer survival remains largely unknown. We sought to determine pre- and post-diagnosis dietary composition, glycemic load (GL), inflammatory potential (dietary inflammatory index) and quality [Canadian Healthy Eating Index (C-HEI) 2005] associations with disease-free (DFS) and overall survival (OS) among endometrial cancer survivors. In addition, we assessed associations between dietary changes with OS and explored obesity/physical activity effect modification.

METHODS

Survivors, diagnosed in Alberta, Canada between 2002 and 2006, completed past-year, food-frequency questionnaires at-diagnosis (n = 503) and 3-year follow-up (n = 395). Participants were followed to death or January 2022. Cox proportional regression estimated HR [95% confidence intervals (CI)] for dietary survival associations.

RESULTS

During 16.9 median years of follow-up, 138 participants had a DFS event and 120 died. Lower pre-diagnosis GL (HRT1vsT3, 0.49; 95% CI, 0.25-0.97) and greater post-diagnosis energy intakes (EI) from total- and monounsaturated-fat (HRT3vsT1, 0.48; 95% CI, 0.26-0.87) were associated with better OS. Higher pre-diagnosis C-HEI, less inflammatory diets and lower added sugar intakes were nonlinearly associated with better DFS. Consistently low pre- to post-diagnosis EI from carbohydrates and total-fats were associated with better (HR, 0.36; 95% CI, 0.18-0.72) and worse (HR, 2.26; 95% CI, 1.21-4.20) OS, respectively. Decreased pre- to post-diagnosis C-HEI was associated with worse OS. In stratified analysis, healthy diets were most beneficial for survivors with obesity and physical inactivity.

CONCLUSIONS

Adherence to higher quality dietary patterns were associated with better survival.

IMPACT

Our study provides novel evidence that both pre- and post-diagnosis diet are important prognostic factors for endometrial cancer survivors. Post-diagnosis survival associations with diet composition and quality highlight the potential for future interventions.

Obesity among African American people in the United States: A review

Obesity is a growing public health crisis in the United States and is associated with a substantial disease burden due to an increased risk for multiple complications, including cardiovascular and metabolic diseases. As highlighted in this review, obesity disproportionately affects the African American population, women in particular, regardless of socioeconomic status. Structural racism remains a major contributor to health disparities between African American people and the general population, and it limits access to healthy foods, safe spaces to exercise, adequate health insurance, and medication, all of which impact obesity prevalence and outcomes. Conscious and unconscious interpersonal racism also impacts obesity care and outcomes in African American people and may adversely affect interactions between health care practitioners and patients. To reduce health disparities, structural racism and racial bias must be addressed. Culturally relevant interventions for obesity management have been successfully implemented that have shown benefits in weight management and risk-factor reduction. Strategies to improve health care practitioner-patient engagement should also be implemented to improve health outcomes in African American people with obesity. When managing obesity in African American people, it is critical to take a holistic approach and to consider an individual's social and cultural context in order to implement a successful treatment strategy.

Obesity among Latinx people in the United States: A review

Obesity is a serious, chronic disease that is associated with a range of adiposity-based comorbidities, including cardiovascular disease, type 2 diabetes, and nonalcoholic fatty liver disease. In the United States, obesity is a public health crisis, affecting more than 40% of the population. Obesity disproportionately affects Latinx people, who have a higher prevalence of obesity and related comorbidities (such as cardiovascular disease, type 2 diabetes, and nonalcoholic fatty liver disease) compared with the general population. Many factors, including genetic predisposition, environmental factors, traditional calorie-dense Latinx diets, family dynamics, and differences in socioeconomic status, contribute to the increased prevalence and complexity of treating obesity in the Latinx population. Additionally, significant heterogeneity within the Latinx population and disparities in health care access and utilization between Latinx people and the general population add to the challenge of obesity management. Culturally tailored interventions have been successful for managing obesity and related comorbidities in Latinx people. Antiobesity medications and bariatric surgery are also important options for obesity treatment in Latinx people. As highlighted in this review, when managing obesity in the Latinx population, it is critical to consider the impact of genetic, dietary, cultural, and socioeconomic factors, in order to implement an individualized treatment strategy.

Differences in gastrointestinal hormones and appetite ratings between individuals with and without obesity-A systematic review and meta-analysis

Determining if gastrointestinal (GI) hormone response to food intake differs between individuals with, and without, obesity may improve our understanding of obesity pathophysiology. A systematic review and meta-analysis of studies assessing the concentrations of GI hormones, as well as appetite ratings, following a test meal, in individuals with and without obesity was undertaken. Systematic searches were conducted in the databases MEDLINE, Embase, Cochrane Library, PsycINFO, Web of Science, and ClinicalTrials.gov. A total of 7514 unique articles were retrieved, 115 included in the systematic review, and 70 in the meta-analysis. The meta-analysis compared estimated standardized mean difference in GI hormones' concentration, as well as appetite ratings, between individuals with and without obesity. Basal and postprandial total ghrelin concentrations were lower in individuals with obesity compared with controls, and this was reflected by lower postprandial hunger ratings in the former. Individuals with obesity had a lower postprandial concentration of total peptide YY compared with controls, but no significant differences were found for glucagon-like peptide 1, cholecystokinin, or other appetite ratings. A large methodological and statistical heterogeneity among studies was found. More comprehensive studies are needed to understand if the differences observed are a cause or a consequence of obesity.

Appetite ratings and ghrelin concentrations in young adults after administration of a balanced meal. Does sex matter?

Background

Sex-based differences in appetite ratings have been observed previously. Ghrelin is the only known orexigenic peptide hormone. Sex differences in postprandial ghrelin responses may underlie different perceptions of hunger and satiety, but results are conflicting. We conducted a parallel study to evaluate sex differences in postprandial appetite ratings and ghrelin concentration after administration of a physiological meal among students of University of Milan.

Methods

Twenty-four healthy, normal weight volunteers (12 men and 12 women) aged 18–35 years were recruited. A balanced mixed meal meeting 40% of the estimated daily energy expenditure and providing 60% of calories from carbohydrates, 25% from lipids and 15% from protein was administrated. Sex differences in appetite ratings (satiety, hunger, fullness and desire to eat) and magnitude of ghrelin suppression during postprandial period (up to 180 min) were determined.

Results

In the fasting state, men and women did not differ in appetite ratings and ghrelin concentrations. After feeding, women tended to reach peak of satiety earlier than men, who in turn reached the nadir of hunger later than women (median: 30 min, interquartile range (IQR): 1; 120 vs. 1 min, IQR 1; 1, p = 0.007). Ghrelin suppression was greater in women (median decremental AUC − 95, IQR − 122; − 66) than in men (median decremental AUC − 47, IQR − 87; − 31, p = 0.041).

Conclusions

These findings suggest sex differences in the postprandial appetite regulation that might be important for nutritional strategy to prevent and treat obesity and eating disorders.

Dysregulation of hepatic metabolism with obesity: factors influencing glucose and lipid metabolism

The liver is a key metabolic organ that undertakes a multitude of physiological processes over the course of a day, including intrahepatic lipid and glucose metabolism which plays a key role in the regulation of systemic lipid and glucose concentrations. It serves as an intermediary organ between exogenous (dietary) and endogenous energy supply to extrahepatic organs. Thus, perturbations in hepatic metabolism can impact widely on metabolic disease risk. For example, the accumulation of intra-hepatocellular TAG (IHTG), for which adiposity is almost invariably a causative factor may result in dysregulation of metabolic pathways. Accumulation of IHTG is likely due to an imbalance between fatty acid delivery, synthesis and removal (via oxidation or export as TAG) from the liver; insulin plays a key role in all of these processes.

Absence of a sexual dimorphism in postprandial glucose metabolism after administration of a balanced mixed meal in healthy young volunteers

BACKGROUND/OBJECTIVES

A different ability to regulate glucose homeostasis between men and women may contribute to their difference in diabetes prevalence and in its predisposing conditions. Data on this issue are controversial because of heterogeneous protocols and insufficient control of confounders affecting glucose metabolism like age, body composition, and physical activity level. To clarify this issue, we compared among sexes the postprandial glucose metabolism after the administration of a balanced mixed meal normalized to daily energy expenditure.

SUBJECTS/METHODS

Thirty-six healthy young volunteers (18 men and 18 women; age, 23.9 ± 2.8 years; BMI, 21.9 ± 1.7 kg/m²) were recruited for the experiment. After overnight fast, subjects consumed a mixed meal providing 40% of daily energy expenditure (60% carbohydrates, 25% lipids, 15% proteins) estimated multiplying resting energy expenditure, obtained by Harris & Benedict equation, for the corresponding physical activity level. Blood was sampled at 0, 10, 20, 30, 45, 60, 90, 120, and 180 min and serum concentrations of glucose, insulin, and C-peptide were measured.

RESULTS

Fasting serum glucose concentrations were lower in women than in men, while fasting insulin and C-peptide concentrations did not differ between sexes. Linear mixed models did not show any significant effect of sex and sex # time interaction on postprandial serum glucose, insulin, and C-peptide concentrations. The comparison of areas under the curve between the sexes revealed similar glycemic, insulinemic, and C-peptide postprandial responses between men and women.

CONCLUSIONS

Our results do not support the hypothesis of a sexual dimorphism in the regulation of carbohydrate metabolism in young when a mixed meal normalized on individual daily energy expenditure is ingested.

Hormone replacement therapy in relation to the risk of colorectal cancer in women by BMI: a multicentre study with propensity score matching

BACKGROUND

Epidemiological evidence about hormone replacement therapy and colorectal carcinogenesis by demographic and clinical traits remains unclear. We aimed to assess this postulated association in a large multicentre study and further explore the modification effect by BMI and others.

METHODS

We retrospectively collected records of women diagnosed with colorectal cancer (CRC) at the age of 50 years and older during 2014-2017 and their HRT dispensing prior to CRC diagnosis in three tertiary hospitals in China. CRC cases were matched with controls at a ratio of 1:3 using nearest neighbour propensity scores matching to better control for the remaining imbalance between groups, which generated a total of 824 cases with 2472 controls.

RESULTS

Our study confirmed the inversed association between colorectal cancer risk and hormone replacement therapy (OR, 0.62; 95% CI, 0.54-0.75), which was more prominent among women having multiple HRT dispenses (OR, 0.60; 95% CI, 0.52-0.76). Furthermore, significant associations were consistently observed for the short-term (OR, 0.69; 95% CI, 0.57-0.88), middle-term (OR, 0.51; 95% CI, 0.41-0.66), and long-term HRT users (OR, 0.70; 95% CI, 0.43-0.90). Estrogen-related regimen reduced CRC risk more than progestogen-only. We, for the first time, found that the modifying effect of BMI on HRT use and CRC risk was in different ways when BMI was categorized by a medium level of 27.

CONCLUSION

Our findings mainly suggest that there might be a different mechanism for the reversed association between HRT and colorectal tumorigenesis by BMI level, providing thoughts on clinical treatment of CRC.

Fresh Mango Consumption Promotes Greater Satiety and Improves Postprandial Glucose and Insulin Responses in Healthy Overweight and Obese Adults

Mangos are an understudied fruit rich in fiber and polyphenols that have been linked to better metabolic outcomes and promotion of satiety. The purpose of this study was to examine the effect of mango consumption on postprandial glucose, insulin, and satiety responses. Using a randomized crossover study design, 23 overweight and obese men and women consumed 100 kcal snacks of fresh mangos or isocaloric low-fat cookies on two separate occasions. Insulin and satiety hormones were measured at baseline and 45 min post-snack consumption. Glucose was measured at baseline, 30, 60, 90, and 120 min after snack consumption. Satiety questionnaires were completed at baseline and every 20 min for 120 min post-consumption. Both mangos and low-fat cookies increased insulin, with a significantly lower increase for mangos compared with low-fat cookies at 45 min post-snack consumption (P ≤ .05). Glucose increased at 30 min for both snacks; however, the increase was significantly higher for low-fat cookie consumption (P ≤ .05). Cholecystokinin increased after mangos and low-fat cookie consumption (P ≤ .05); however, no differences were detected between the snacks. Adiponectin increased after mango consumption (P ≤ .05) but not after low-fat cookies. Mango consumption reduced hunger, anticipated food consumption and thirst, and increased feelings of fullness (P ≤ .05). Low-fat cookie consumption increased fullness for a shorter time period and did not reduce participants' desire to eat. These results suggest that relative to a refined cookie snack, mangos promote greater satiety and improve postprandial glycemic responses. Future research on long-term effects of mango consumption on food intake, weight control, and glucose homeostasis is warranted. Clinical Trial Registration number: #NCT03957928.

Changes in ghrelin, substance P and vasoactive intestinal peptide levels in the gastroduodenal mucosa of patients with morbid obesity

AIMS

The aim of the study was to assess changes in levels of substance P (SP), vasoactive intestinal peptide (VIP) and ghrelin in the gastroduodenal mucosa of obese individuals, which has not been studied before.

METHODS

Forty-six patients with a body mass index (BMI) of >40 kg/m² and 20 patients with a BMI of 18-25 kg/m² were included in the study. VIP and SP levels in the fundus, antrum and duodenal mucosa were measured in freshly frozen tissues using enzyme-linked immunosorbent assay (ELISA). Fasting levels of ghrelin in blood were also measured with ELISA. Tissue levels of ghrelin were assessed by immunohistochemical staining, and immunoreactivity scores were used for ghrelin evaluation in tissues.

RESULTS

Antrum SP levels were higher in the obese group than in the control group. A significant number of obese patients had low VIP levels in the fundus and antrum. Intense ghrelin staining was observed in a limited number of cells in the mucosal area of the gastric fundus that was similar in the control and patient groups. In the antrum and duodenum, ghrelin staining was low in all the samples examined.

CONCLUSION

Here, we found that SP levels are increased, while VIP levels are decreased in the antrum of morbidly obese individuals. Previous studies show that SP increases gastroduodenal motility, that VIP slows it down, and that the gastric emptying rate is higher in obese individuals, preventing negative feedback mechanisms upon food intake. Therefore, increases in SP and decreases in VIP levels in the antrum may contribute to obesity by accelerating gastric emptying.

Gastrointestinal peptides in eating-related disorders

Food intake is tightly controlled by homeostatic signals sensitive to metabolic need for the regulation of body weight. This review focuses on the peripherally-secreted gastrointestinal peptides (i.e., ghrelin, cholecystokinin, glucagon-like peptide 1, and peptide tyrosine tyrosine) that contribute to the control of appetite and discusses how these peptides or the signals arising from their release are disrupted in eating-related disorders across the weight spectrum, namely anorexia nervosa, bulimia nervosa, and obesity, and whether they are normalized following weight restoration or weight loss treatment. Further, the role of gut peptides in the pathogenesis and treatment response in human weight conditions as identified by rodent models are discussed. Lastly, we review the incretin- and hormone-based pharmacotherapies available for the treatment of obesity and eating-related disorders.

Attenuated Postprandial GLP-1 Response in Parkinson's Disease

The incretin hormone glucagon-like peptide 1 (GLP-1) has neuroprotective effects in animal models of Parkinson’s disease (PD), and GLP-1 receptor agonists are associated with clinical improvements in human PD patients. GLP-1 is produced and secreted by intestinal L-cells in response to consumption of a meal. Specifically, intestinal microbiota produce short chain fatty acids (SCFA) which, in turn, promote secretion of GLP-1 into the systemic circulation, from which it can enter the brain. Our group and others have reported that PD patients have an altered intestinal microbial community that produces less SCFA compared to age-matched controls. In this report, we demonstrate that PD patients have diminished GLP-1 secretion in response to a meal compared to their household controls. Peak postprandial GLP-1 levels did not correlate with PD disease severity, motor function, or disease duration. These data provide the scientific rationale for future studies designed to elucidate the role of GLP-1 in the pathogenesis of PD and test the potential utility of GLP-1-directed therapies.

Leg Fidgeting During Prolonged Sitting Improves Postprandial Glycemic Control in People with Obesity

OBJECTIVE

Studies have shown that fidgeting augments metabolic demand and increases blood flow to the moving limbs, whereas prolonged sitting suppresses these factors and exacerbates postprandial glucose excursions. Therefore, the hypothesis of this study was that leg fidgeting during prolonged sitting would improve postprandial glycemic control.

METHODS

Adults with obesity (n = 20) participated in a randomized crossover trial in which blood glucose and insulin concentrations were measured during a 3-hour sitting period following the ingestion of a glucose load (75 g). During sitting, participants either remained stationary or intermittently fidgeted both legs (2.5 minutes off and 2.5 minutes on). Accelerometer counts, oxygen consumption, and popliteal-artery blood flow were also measured during the sitting period.

RESULTS

As expected, fidgeting increased accelerometer counts (P < 0.01), oxygen consumption (P < 0.01), and blood flow through the popliteal artery (P < 0.05). Notably, fidgeting lowered both glucose (P < 0.01) and insulin (P < 0.05) total area under the curve (AUC) and glucose incremental AUC (P < 0.05). Additionally, there was a strong negative correlation between fidgeting-induced increases in blood flow and reduced postprandial glucose AUC within the first hour (r = -0.569, P < 0.01).

CONCLUSIONS

Leg fidgeting is a simple, light-intensity physical activity that enhances limb blood flow and can be incorporated during prolonged sitting to improve postprandial glycemic control in people with obesity.

Old Paradoxes and New Opportunities for Appetite Control in Obesity

Human obesity is accompanied by alterations in the blood concentrations of multiple circulating appetite regulators. Paradoxically, most of the appetite-inhibitory hormones are elevated in nonsyndromic obesity, while most of the appetite stimulatory hormones are reduced, perhaps reflecting vain attempts of regulation by inefficient feedback circuitries. In this context, it is important to understand which appetite regulators exhibit a convergent rather than paradoxical behavior and hence are likely to contribute to the maintenance of the obese state. Pharmacological interventions in obesity should preferentially consist of the supplementation of deficient appetite inhibitors or the neutralization of excessive appetite stimulators. Here, we critically analyze the current literature on appetite-regulatory peptide hormones. We propose a short-list of appetite modulators that may constitute the best candidates for therapeutic interventions.

Glycemic Index, Glycemic Load, and Cardiovascular Disease and Mortality

BACKGROUND

Most data regarding the association between the glycemic index and cardiovascular disease come from high-income Western populations, with little information from non-Western countries with low or middle incomes. To fill this gap, data are needed from a large, geographically diverse population.

METHODS

This analysis includes 137,851 participants between the ages of 35 and 70 years living on five continents, with a median follow-up of 9.5 years. We used country-specific food-frequency questionnaires to determine dietary intake and estimated the glycemic index and glycemic load on the basis of the consumption of seven categories of carbohydrate foods. We calculated hazard ratios using multivariable Cox frailty models. The primary outcome was a composite of a major cardiovascular event (cardiovascular death, nonfatal myocardial infarction, stroke, and heart failure) or death from any cause.

RESULTS

In the study population, 8780 deaths and 8252 major cardiovascular events occurred during the follow-up period. After performing extensive adjustments comparing the lowest and highest glycemic-index quintiles, we found that a diet with a high glycemic index was associated with an increased risk of a major cardiovascular event or death, both among participants with preexisting cardiovascular disease (hazard ratio, 1.51; 95% confidence interval [CI], 1.25 to 1.82) and among those without such disease (hazard ratio, 1.21; 95% CI, 1.11 to 1.34). Among the components of the primary outcome, a high glycemic index was also associated with an increased risk of death from cardiovascular causes. The results with respect to glycemic load were similar to the findings regarding the glycemic index among the participants with cardiovascular disease at baseline, but the association was not significant among those without preexisting cardiovascular disease.

CONCLUSIONS

In this study, a diet with a high glycemic index was associated with an increased risk of cardiovascular disease and death. (Funded by the Population Health Research Institute and others.).

Walking Initiated 20 Minutes before the Time of Individual Postprandial Glucose Peak Reduces the Glucose Response in Young Men with Overweight or Obesity: A Randomized Crossover Study

BACKGROUND

Although a single bout of postmeal exercise can lower postprandial glucose (PPG), its optimal timing remains unclear.

OBJECTIVE

This study aimed to investigate the effect of exercise timing using an individualized approach on PPG in overweight or obese young men.

METHODS

Twenty men [age: 23.0 ± 4.3 y; BMI (kg/m2): 27.4 ± 2.8] each completed three 240-min trials in a randomized order separated by 6-14 d: 1) sitting (SIT), 2) walking initiated at each participant's PPG-peak time (PPGP) (iP), and 3) walking initiated 20 min before the PPGP (20iP). For each participant, PPGP was predetermined using continuous glucose monitoring. Walking was performed at 50% maximal oxygen consumption for 30 min. Venous blood was collected at 15- and 30-min intervals for 0-120 min and 120-240 min, respectively. The primary outcome was plasma PPG. Generalized estimating equations were used for comparison between trials.

RESULTS

Compared with SIT, the 4-h incremental AUCs (iAUCs) for plasma PPG (-0.6 mmol · L-1 · h; P = 0.047) and insulin (-28.7%, P < 0.001) were reduced in 20iP only, and C-peptide concentrations were lower after iP (-14.9%, P = 0.001) and 20iP (-28.7%, P < 0.001). Plasma insulin (-11.1%, P = 0.006) and C-peptide (-8.3%, P = 0.012) were lower due to the 20iP compared with iP treatment. Finally, PPG reductions due to iP and 20iP occurred only in men with a BMI > 27.5 kg/m2 (iP, -11.2%; 20iP, -14.7%; P = 0.047) and higher glucose iAUC values during SIT (iP, -25.5%; 20iP, -25.7%; P < 0.001).

CONCLUSIONS

Walking initiated 20 min before PPGP lowered PPG and plasma insulin and C-peptide concentrations in young men with overweight or obesity, in particular in those with high BMI or glucose iAUC values during SIT; it also lowered plasma insulin and C-peptide concentrations more effectively than did exercise initiated at PPGP. This trial was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn/index.aspx) as ChiCTR1900023175.

Appetite-Regulating Hormones Are Reduced After Oral Sucrose vs Glucose: Influence of Obesity, Insulin Resistance, and Sex

CONTEXT

Fructose compared to glucose has adverse effects on metabolic function, but endocrine responses to oral sucrose vs glucose is not well understood.

OBJECTIVE

We investigated how oral sucrose vs glucose affected appetite-regulating hormones, and how biological factors (body mass index [BMI], insulin sensitivity, sex) influence endocrine responses to these 2 types of sugar.

DESIGN

Sixty-nine adults (29 men; 23.22 ± 3.74 years; BMI 27.03 ± 4.96 kg/m2) completed the study. On 2 occasions, participants consumed 300-mL drinks containing 75 g of glucose or sucrose. Blood was sampled at baseline, 10, 35, and 120 minutes post drink for plasma glucose, insulin, glucagon-like peptide (GLP-1)(7-36), peptide YY (PYY)total, and acyl-ghrelin measures. Hormone levels were compared between conditions using a linear mixed model. Interaction models were performed, and results were stratified to assess how biological factors influence endocrine responses.

RESULTS

Sucrose vs glucose ingestion provoked a less robust rise in glucose (P < .001), insulin (P < .001), GLP-1 (P < .001), and PYY (P = .02), whereas acyl-ghrelin suppression was similar between the sugars. We found BMI status by sugar interactions for glucose (P = .01) and PYY (P = .03); obese individuals had smaller increases in glucose and PYY levels after consuming sucrose vs glucose. There were interactions between insulin sensitivity and sugar for glucose (P = .003) and insulin (P = .04), and a sex by sugar interaction for GLP-1 (P = .01); men demonstrated smaller increases in GLP-1 in response to oral sucrose vs glucose.

CONCLUSION

Sucrose is less efficient at signaling postprandial satiation than glucose, and biological factors influence differential hormone responses to sucrose vs glucose consumption.

Effects of gastrointestinal delivery of non-caloric tastants on energy intake: a systematic review and meta-analysis

Purpose

Taste receptors are expressed throughout the gastrointestinal tract. The activation of post-oral taste receptors using tastants could provide a non-invasive treatment option in combating the obesity epidemic. The aim of this review was to examine the effect of post-oral delivery of non-caloric tastants on eating behavior reflected by primary outcome energy intake and secondary outcomes GI symptoms and perceptions and potential underlying mechanisms. This review was conducted according to the PRISMA guidelines for systematic reviews.

Methods

A systematic literature search of the Cochrane, PubMed, Embase, and Medline databases was performed. This systematic review and meta-analysis was registered in the PROSPERO database on 26 February 2020 (ID: CRD42020171182). Two researchers independently screened 11,912 articles and extracted information from 19 articles. If at least two studies investigated the effect of the same taste compound on primary outcome energy intake, a meta-analysis was performed to determine pooled effect sizes.

Results

Nineteen papers including healthy volunteers were included. In the 19 papers analyzed, effects of various tastants were investigated in healthy volunteers. Most extensively investigated were bitter tastants. The meta-analysis of effects of bitter tastants showed a significant reduction in energy intake of 54.62 kcal (95% CI − 78.54 to − 30.69, p = 0.0014).

Conclusions

Bitter stimuli are most potent to influence eating behavior. Energy intake decreased after post-oral delivery of bitter tastants. This highlights the potential of a preventive role of bitter tastants in battling the obesity epidemic.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02485-4.

Revisiting the Compensatory Theory as an explanatory model for relapse in obesity management

Weight regain remains the main challenge in obesity management, and its etiology remains elusive. The aim of the present review was to revise the available evidence regarding the "Compensatory Theory," which is an explanatory model of relapse in obesity treatment, and to propose alternative mechanisms that can contribute to weight regain. It has been proposed, and generally accepted as true, that when a person loses weight the body fights back, with physiological adaptations on both sides of the energy balance equation that try to bring body weight back to its original state: this is the Compensatory Theory. This theory proposes that the increased orexigenic drive to eat and the reduced energy expenditure that follow weight loss are the main drivers of relapse. However, evidence showing a link between these physiological adaptations to weight loss and weight regain is lacking. Here, we propose that the physiological adaptations to weight loss, both at the level of the homeostatic appetite control system and energy expenditure, are in fact a normalization to a lower body weight and not drivers of weight regain. In light of this we explore other potential mechanisms, both physiological and behavioral, that can contribute to the high incidence of relapse in obesity management. More research is needed to clearly ascertain whether the changes in energy expenditure and homeostatic appetite markers seen in reduced-obese individuals are a compensatory mechanism that drives relapse or a normalization towards a lower body weight, and to explore alternative hypotheses that explain relapse in obesity management.

Changes in the Homeostatic Appetite System After Weight Loss Reflect a Normalization Toward a Lower Body Weight

OBJECTIVE

To compare appetite markers in reduced-obese individuals with a nonobese control group.

METHODS

A total of 34 adults with obesity who lost 17% body weight at week 13 and maintained this weight loss (WL) at 1 year were compared with 33 nonobese controls matched for body composition. Basal and postprandial subjective appetite ratings and appetite-related hormone concentrations (ghrelin, total peptide YY, peptide YY3-36, total and active glucagon-like peptide 1, and cholecystokinin) were measured in all participants and repeated at week 13 and 1 year in the weight-reduced group.

RESULTS

WL led to a reduction in prospective food consumption and an increase in feelings of hunger, fullness, and ghrelin secretion (basal and postprandial), but these new ratings were no different from those seen in controls. Postprandial concentrations of active glucagon-like peptide 1, total peptide YY, and cholecystokinin were lower in individuals with obesity at all time points compared with controls.

CONCLUSION

The increased drive to eat (both subjective feelings of hunger and ghrelin concentrations) seen in reduced-obese individuals, both after acute and sustained WL, reflects a normalization toward a lower body weight. Overall, WL does not have a sustained negative impact on satiety peptide secretion, despite a blunted secretion in individuals with obesity compared with nonobese controls.

The importance of language in engagement between health-care professionals and people living with obesity: a joint consensus statement

Obesity is a chronic condition that requires long-term management and is associated with unprecedented stigma in different settings, including during interactions with the health-care system. This stigma has a negative effect on the mental and physical health of people with obesity and can lead to avoidance of health care and disruption of the doctor-patient relationship. Considerable evidence exists to suggest that simply having a conversation about obesity can lead to weight loss, which translates into health benefits. However, both health-care practitioners and people living with obesity report apprehension in initiating this conversation. We have collaborated with stakeholders from Obesity UK, physicians, dieticians, clinical psychologists, obesity researchers, conversation analysts, nurses, and representatives from National Health Service England Diabetes and Obesity. This group has contributed to the production of this consensus statement, which addresses how people living with obesity wish to have their condition referred to and provides practical guidance for health-care professionals to facilitate collaborative and supportive discussions about obesity. Expert stakeholders consider that changes to language used at the point of care can alleviate the stigma of obesity within the health-care system and support improved outcomes for both people living with obesity and for the health-care system.

Effect of Dietary Macronutrients on Postprandial Glucagon and Insulin Release in Obese and Normal-Weight Women

The aim of the study was to assess the effect of dietary macronutrients on circulating glucagon and insulin levels in obese and normal-weight women. Potentially, the impaired release of glucagon may proceed abnormal glucose metabolism in obese patients ahead of overt diabetes. In 20 insulin-sensitive women (11 obese and 9 normal-weight), plasma concentrations of insulin and glucagon levels were assessed before and after 3 different macronutrient test meals. AUC_total insulin in the obese group was increased after protein and carbohydrates compared to fatty test meal consumption (3981 ± 2171 and 4869 ± 2784 vs. 2349 ± 1004 μIU∗h/m, p < 0.05, respectively), but without a difference between protein and carbohydrates ingestion. However, in the normal-weight group, AUC_total insulin was increased after carbohydrates compared to fatty test meal ingestion (3929 ± 1719 vs. 2231 ± 509 μIU∗h/ml, p < 0.05) and similar after carbohydrate and protein as well as after fatty and protein test meals (3929 ± 1719 vs. 2231 ± 509 vs. 3046 ± 1406 μIU∗h/ml, respectively). However, AUC_total insulin was significantly increased in obese compared to normal-weight women only after carbohydrate test meal ingestion (4869 ± 2784 vs. 3929 ± 1719 μIU∗h/ml, p < 0.05). AUC_total glucagon was similar after carbohydrate, protein, and fatty test meals ingestion in obese and normal-weight women (921 ± 356 vs. 957 ± 368 vs. 926 ± 262 ng∗h/ml and 1196 ± 14 vs. 1360 ± 662 vs. 1792 ± 1176 ng∗h/ml, respectively). AUC_total glucagon was significantly lower in obese than normal-weight women after a fatty meal (926 ± 262 vs. 1792 ± 1176 ng∗h/ml, p < 0.01). Postprandial glucagon secretion is not related to the macronutrient composition of the meal in normal-weight women since postprandial glucagon concentrations were stable and did not change after carbohydrate, protein, and fatty test meals. Lower glucagon secretion was observed in obese subjects after fatty meal consumption when compared to normal-weight subjects. Postprandial insulin profile was significantly higher after carbohydrate than fatty test meal intake in the obese group and did not differ between obese and normal-weight groups after carbohydrate, protein, and fatty test meals consumption. Impaired glucagon secretion after fatty meat suggests early pancreatic alpha-cell dysfunction, after a carbohydrate meal is a compensatory mechanism.

The Effect of Potato Protease Inhibitor II on Gastrointestinal Hormones and Satiety in Humans During Weight Reduction

CONTEXT

It is questioned whether the potato protein protease inhibitor II (PI2) reduces appetite and exerts effects on the satiety hormone cholecystokinin (CCK).

OBJECTIVE

To investigate PI2 impact on gastrointestinal hormones and appetite measures during weight reduction.

DESIGN

In a randomized, placebo-controlled trial over 20 weeks, fifty-two overweight/obese participants (BMI 25.2-38.0 kg/m²) received a protein-rich diet (30%) adjusted to 500 kcal below their individual daily needs. Subjects ingested a capsule containing either PI2 (150 mg) or placebo twice daily 1 hr before lunch and dinner. At week 0 and week 10 participants joined breakfast test meals to determine CCK, GLP-1, ghrelin, leptin, glucose and insulin concentrations in a time course experimental manner. Appetite sensations were measured on test meal days and in week 4, 9, 14 and 19 using visual analogue scales.

RESULTS

Weight loss at week 10 and 20 in the PI2 group was 4.3±3.1 kg and 5.6±4.1 kg, in the control group: 4.7±4.0 kg and 6.8±3.7 kg. A significant effect of PI2 on circulating CCK levels was observed at week 10. The other hormones were unaffected by PI2. At week 10, PI2 group subjects showed higher satiety and decreased desire to eat compared to placebo. During study duration, PI2 showed a significant impact on appetite ratings prior to lunch, one hour before dinner and just before dinner.

CONCLUSION

PI2 increased circulating CCK plasma levels during the diet intervention. Likewise, PI2 modulated appetite sensation from week 4 to 20. The study demonstrated that the PI2 can modulate a key satiety signal.

Exploration of associations between the FTO rs9939609 genotype, fasting and postprandial appetite-related hormones and perceived appetite in healthy men and women

BACKGROUND

The fat mass and obesity-associated gene (FTO) rs9939609 A-allele has been associated with obesity risk. Although the exact mechanisms involved remain unknown, the FTO rs9939609 A-allele has been associated with an impaired postprandial suppression of appetite.

OBJECTIVES

To explore the influence of FTO rs9939609 genotype on fasting and postprandial appetite-related hormones and perceived appetite in a heterogeneous sample of men and women.

DESIGN

112 healthy men and women aged 18-50-years-old completed three laboratory visits for the assessment of FTO rs9939609 genotype, body composition, aerobic fitness, resting metabolic rate, visceral adipose tissue, liver fat, fasting leptin, and fasting and postprandial acylated ghrelin, total PYY, insulin, glucose and perceived appetite. Participants wore accelerometers for seven consecutive days for the assessment of physical activity and sedentary behaviour. Multivariable general linear models quantified differences between FTO rs9939609 groups for fasting and postprandial appetite outcomes, with and without the addition of a priori selected physiological and behavioural covariates. Sex-specific univariable Pearson's correlation coefficients were quantified between the appetite-related outcomes and individual characteristics.

RESULTS

95% confidence intervals for mean differences between FTO rs9939609 groups overlapped zero in unadjusted and adjusted general linear models for all fasting (P ≥ 0.28) and postprandial (P ≥ 0.19) appetite-related outcomes. Eta² values for explained variance attributable to FTO rs9939609 were <5% for all outcomes. An exploratory correlation matrix indicated that associations between fasting and postprandial acylated ghrelin, total PYY and general or abdominal adiposity were also small (r = -0.23 to 0.15, P ≥ 0.09). Fasting leptin, glucose and insulin and postprandial insulin concentrations were associated with adiposity outcomes (r = 0.29 to 0.81, P ≤ 0.033).

CONCLUSIONS

Associations between the FTO rs9939609 genotype and fasting or postprandial appetite-related outcomes were weak in healthy men and women.

Six Weeks of Morning Fasting Causes Little Adaptation of Metabolic or Appetite Responses to Feeding in Adults with Obesity

OBJECTIVE

The aim of this study was to determine the effects of sustained morning fasting or breakfast consumption on metabolism, energy intake, and appetite in healthy adults with obesity.

METHODS

An independent-measures randomized controlled trial with baseline and follow-up laboratory assessment days separated by a 6-week intervention of either morning fasting (0 kcal until 12:00 pm) or daily breakfast (> 700 kcal by 11:00 am) was performed. Measures included metabolic outcomes (glucose, insulin, nonesterified fatty acids), hormones regulating appetite (total/acylated ghrelin, peptide YY, leptin), and energy expenditure (diet-induced thermogenesis) parameters throughout a laboratory test day and ad libitum intake following a fixed breakfast.

RESULTS

Allocation to fasting versus breakfast resulted in minimal adaptation as reflected by the metabolic outcomes or the majority of appetite regulatory outcomes for either area under curve or time-course-based measures (P > 0.05). Ad libitum lunch intake was not different (P = 0.13), nor was diet-induced thermogenesis or a composite appetite score (both P > 0.10). However, there was a reduced total area under the curve for peptide YY (P = 0.05) and increased postprandial hunger ratings (P = 0.05) in the breakfast group.

CONCLUSIONS

There was little evidence of metabolic adaptation to acute feeding or negative consequences from sustained morning fasting. This indicates that previously observed differences between breakfast consumers and skippers may be acute effects of feeding or may have resulted from other lifestyle factors.

A 6-week supplementation with grape pomace to subjects at cardiometabolic risk ameliorates insulin sensitivity, without affecting other metabolic syndrome markers

Grape polyphenols have shown a promising role in the modulation of metabolic syndrome (MetS), mostly in animal models. However, clinical studies are scarce and they usually only consider a fraction of polyphenols, ignoring the non-extractable polyphenols (high molecular weight compounds or associated with macromolecules such as dietary fibre). This study aimed at evaluating the effect of grape pomace, rich in both extractable and non-extractable polyphenols, on markers of MetS. Fifty subjects (22 women) aged 20-65 with at least two MetS factors were randomly assigned to the product (daily dose of 8 g of dried grape pomace) or to the control group in a 6 week crossover design with a 4 week wash-out. Samples were collected at the beginning and at the end of both periods; half of the participants were subjected to an oral glucose tolerance test at the beginning and the end of the supplementation period. Grape pomace supplementation significantly improved fasting insulinaemia (p < 0.01), without affecting other cardiometabolic risk parameters. A tendency towards an improvement in postprandial insulinaemia was observed, particularly in those subjects with higher fasting insulin levels. Therefore, supplementation with grape pomace may be a strategy for improving insulin sensitivity in subjects at high cardiometabolic risk.

Assessing the influence of fasted and postprandial states on day-to-day variability of appetite and food preferences

INTRODUCTION

Ratings of subjective appetite and food hedonics provide valuable information about energy and macronutrient intake. Ensuring reproducibility of measures of subjective appetite, and food liking and wanting is essential for accurate understanding about their implementation in intervention studies.

METHODS

Nineteen participants participated in two separate 10-h test days consisting of 6 test meals. Subjective appetite was measured in the fasted state and periodically across the test day in a postprandial state. Liking and wanting were measured using the Leeds Food Preferences Questionnaire (LFPQ) immediately before and after breakfast, immediately before the second meal, and at the end of the test day.

RESULTS

Reproducibility of appetite scores was similar to those previously reported in males, however females tended to have consistently higher CVs, wider CRs and wider 95% CIs. Variability in food hedonics was of a similar magnitude to subjective appetite with CVs for fasting explicit liking and wanting between 15.3 and 33.4%, correlations for both implicit and explicit liking and wanting between 0.18 and 0.87 and CRs indicating 95% of between-day changes for any given individual should fall within ±43.4 mm of the mean change. Averages of food hedonics during the test day reduced CVs, improved correlations and reduced CRs. Despite no mean change in preceding energy and nutrient intake, individual changes in prior energy and macronutrient intake appeared to influence individual between-day changes in appetite and food hedonics, and appetite and food hedonics were intricately linked.

CONCLUSIONS

Larger subject numbers may be required for appetite studies with female participants due to greater appetite variability. The LFPQ as a tool for measuring implicit and explicit liking and wanting is sufficiently reproducible and improved by averaging multiple measures across a day.

Postprandial gut hormone responses to Hass avocado meals and their association with visual analog scores in overweight adults: A randomized 3 × 3 crossover trial

OBJECTIVE

To evaluate changes in postingestive gut hormone concentrations from the consumption of Hass avocado by addition or inclusion to lunch test meals, and to examine their association with measures of appetite sensation.

METHODS

A randomized 3 × 3 crossover study was conducted with 26 healthy overweight adults. Participants consumed one of three test meals: avocado-free control (C); isoenergic avocado inclusive (AI); and, energy increased avocado added (AA) one week apart. Ghrelin, peptide YY_3-36 (PYY_3-36), gastric inhibitory peptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations were measured at specific times before and following the test meals. Appetite sensations (Hunger, Fullness, Satisfied, Desire, How Much) were self-assessed using a visual analog scale (VAS) tool at matching time points and a Composite VAS score was computed. Mixed models and repeated measures analysis were used to compare differences among the test meals for VAS measurements and gut hormones, and their associations were evaluated using regression analysis.

RESULTS

A decrease in the 3-hour GLP-1 area under the curve (AUC) was observed in the AA meal compared to the C meal (P = 0.03). Negative associations were found for PYY_3-36 and GIP for Hunger, Desire and How Much, and positive associations for Fullness, Satisfied and the Composite VAS score (all P < 0.001). For GLP-1, a negative association for Hunger and a positive association for Satisfied and the Composite VAS score (all P < 0.05) were noted.

CONCLUSIONS

Postprandial responses to PYY_3-36, GIP and GLP-1 concentrations were associated with VAS measures and the Composite VAS score following consumption of test meals in overweight adults.

Effect of gender on the acute effects of whey protein ingestion on energy intake, appetite, gastric emptying and gut hormone responses in healthy young adults

BACKGROUND/OBJECTIVES

Protein supplements, usually drinks rich in whey protein, are used widely for weight loss purposes in overweight adults. Information comparing the effects of whey protein on appetite and energy intake in men and women is limited. The objective was to compare the acute effects of whey-protein intake on energy intake, appetite, gastric emptying and gut hormones in healthy young men and women.

SUBJECTS/METHODS

Gastric emptying (3D-ultrasonography), blood glucose and plasma insulin, glucagon, ghrelin, cholecystokinin (CCK), gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) concentrations (0-180 min), appetite (visual analogue scales), and ad libitum energy intake from a buffet meal (180-210 min) were determined after ingestion of 30 g (120 kcal) or 70 g (280 kcal) whey protein, or a flavoured-water control drink (~2 kcal) in 8 healthy young men (25 ± 2 y, 72 ± 3 kg, 23 ± 1 kg/m²) and 8 women (23 ± 1 y, 64 ± 2 kg, 24 ± 0.4 kg/m²).

RESULTS

There was a protein-load effect on gastric emptying, blood glucose, plasma insulin, glucagon, ghrelin, CCK, GIP and GLP-1 concentrations, and perceptions of hunger, desire to eat and prospective food consumption (P < 0.05). Ad libitum energy intake (average decrease of 206 ± 39 kcal (15 ± 2%) for men and of 46 ± 54 kcal (0 ± 26%) for women for the mean of the intakes after the 30 and 70 g whey-protein loads) and hunger were suppressed more by whey-protein ingestion in men than women (P = 0.046). There was no difference in suppression of energy intake between the 30 and 70 g protein loads (P = 0.75, interaction effect P = 0.19). Consequently, total energy intake (protein drink plus buffet meal) increased more compared to control in women than men (P = 0.010). The drinks emptied more slowly, and plasma glucagon, CCK and GLP-1 increased less after the protein drinks, in women than men (P < 0.05).

CONCLUSION

The acute effects of whey protein ingestion on appetite, energy intake, gastric emptying and gut hormone responses are influenced by gender in healthy young adults.

Diurnal Variation of Sweet Taste Recognition Thresholds Is Absent in Overweight and Obese Humans

Sweet taste thresholds are positively related to plasma leptin levels in normal weight humans: both show parallel diurnal variations and associations with postprandial glucose and insulin rises. Here, we tested whether this relationship also exists in overweight and obese (OW/Ob) individuals with hyperleptinemia. We tested 36 Japanese OW/Ob subjects (body mass index (BMI) > 25 kg/m²) for recognition thresholds for various taste stimuli at seven different time points from 8:00 a.m. to 10:00 p.m. using the staircase methodology, and measured plasma leptin, insulin, and blood glucose levels before each taste threshold measurement. We also used the homeostatic model assessment of insulin resistance (HOMA-IR) to evaluate insulin resistance. The results demonstrated that, unlike normal weight subjects, OW/Ob subjects showed no significant diurnal variations in the recognition thresholds for sweet stimuli but exhibited negative associations between the diurnal variations of both leptin and sweet recognition thresholds and the HOMA-IR scores. These findings suggest that in OW/Ob subjects, the basal leptin levels (~20 ng/mL) may already exceed leptin’s effective concentration for the modulation of sweet sensitivity and that this leptin resistance-based attenuation of the diurnal variations of the sweet taste recognition thresholds may also be indirectly linked to insulin resistance in OW/Ob subjects.

A study of glycaemic effects following acute anthocyanin-rich blueberry supplementation in healthy young adults

The postprandial response to ingested carbohydrate is recognised as a marker of metabolic health. Postprandial hyperglycaemia is observed in type 2 diabetes mellitus and is a significant risk factor for cardiovascular disease. Cognitive deficits are also associated with type 2 diabetes. Therefore interventions which moderate postprandial glucose profiles are desirable. Here we investigated the impact of anthocyanin-rich wild blueberries on postprandial glucose response. Seventeen healthy young adults consumed a range of doses of freeze-dried wild blueberry powder, in smoothie form, in both sugar-matched and no-added-sugar conditions. Plasma glucose was determined by a capillary sampling method at baseline and at regular intervals up to 2.5 hours postprandially. Blueberries were observed to significantly extend the postprandial glucose response beyond the period observed for a sugar-matched control, characteristic of a beneficial glycaemic response. Furthermore, blueberries were observed to reduce peak postprandial glucose levels, although statistical significance was not achieved. The findings suggest a tempering of the postprandial glucose response in the presence of anthocyanin-rich blueberry, and are discussed with reference to likely glucoregulatory mechanisms of action and their implications for cognitive and type 2 diabetes research.

Yacon syrup: Food applications and impact on satiety in healthy volunteers

Syrup obtained from yacon roots could be well positioned as a nutritional product due to its high fructooligosaccharides (FOS) content. Considering this, we examined the potential food applications of yacon syrup, using the focal group methodology, and its sensorial acceptability when incorporated in yogurt. The beneficial effects of the consumption of yacon syrup were studied over a 2-week period in a double-blind placebo-controlled experiment (namely Test A) and other consistent of only one day of yacon syrup consumption (namely Test B) were also evaluated. The doses of yacon syrup for both experiments were 8.74g of FOS/day. Energy intake, hunger, satiety, fullness and prospective food consumption were assessed with analogue scales at the end of each test. The results indicate that the yogurt was the food most suggested by the focus group, and the average of the scores given to the attributes when the yacon syrup was incorporated into a yogurt were: 7.78 for appearance; 7.72 for aroma; 7.02 for flavor and 6.96 for overall acceptability, corresponding to "like very much" and "like moderately". Furthermore, the results indicate that yacon syrup has a positive effect on appetite and its effect was dependent on gender and period of intervention, being statistically significant (P<0.05) in women, after 2-week period. These findings suggested that increasing FOS intake could help to increase satiety, and consequently, be helpful in the management of type 2-diabetes or control of the current high prevalence of overweight or obesity.

Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB

The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials.

Glucagon-like peptide 1 in the pathophysiology and pharmacotherapy of clinical obesity

Though the pathophysiology of clinical obesity is undoubtedly multifaceted, several lines of clinical evidence implicate an important functional role for glucagon-like peptide 1 (GLP-1) signalling. Clinical studies assessing GLP-1 responses in normal weight and obese subjects suggest that weight gain may induce functional deficits in GLP-1 signalling that facilitates maintenance of the obesity phenotype. In addition, genetic studies implicate a possible role for altered GLP-1 signalling as a risk factor towards the development of obesity. As reductions in functional GLP-1 signalling seem to play a role in clinical obesity, the pharmacological replenishment seems a promising target for the medical management of obesity in clinical practice. GLP-1 analogue liraglutide at a high dose (3 mg/d) has shown promising results in achieving and maintaining greater weight loss in obese individuals compared to placebo control, and currently licensed anti-obesity medications. Generally well tolerated, provided that longer-term data in clinical practice supports the currently available evidence of superior short- and long-term weight loss efficacy, GLP-1 analogues provide promise towards achieving the successful, sustainable medical management of obesity that remains as yet, an unmet clinical need.

The effect of fiber-rich milk and equi-carbohydrate snack on glycemic and insulin response and satiety feeling

Background: Additional dietary fibers which can decrease the glycemic response by slowing down digestion whilst maintaining the available carbohydrate content is one approach of healthy diet. This study aimed to compare post-prandial glycemic and insulin response, hunger and satiety feeling after consuming fiber-rich milk compare with equi-carbohydrate food as morning snack in healthy adults.Methods: Cross-over study was conducted on 12 healthy subjects who fulfilled the criteria.  Each test food was given after consuming standard breakfast. Venous blood samples for insulin and glucose level were taken before consuming test food, at 30, 60, 120, and 180 minutes after, and plotted against time to generate a curve. Hunger and satiety assessments were taken by visual analog scale (VAS) after each blood sampling.Results: In average, age was 30.8+4.3 years old, body mass index was 20.6±1.6 kg/m2. Seven of twelve subjects were females. There were significantly differences in postprandial glycemic response (p<0.001), insulin response (p=0.045) and hunger feeling (p=0.021) between the two foods. However, postprandial satiety feelings were not different significantly (p=0.357). The glycemic response area under the curve of fiber-rich milk was significantly lower than the equi-carbohydrate snack (p=0.010). Conclusion: Differences in glycemic and insulin response, and hunger feeling between two test foods, suggesting that fiber-rich milk can be used as an alternative snack for healthy adults. Further study is needed for the use of fiber-rich milk as an alternative snack for pre-diabetic patients.

Differential effects of hunger and satiety on insular cortex and hypothalamic functional connectivity

The insula cortex and hypothalamus are implicated in eating behaviour, and contain receptor sites for peptides and hormones controlling energy balance. The insula encompasses multi‐functional subregions, which display differential anatomical and functional connectivities with the rest of the brain. This study aimed to analyse the effect of fasting and satiation on the functional connectivity profiles of left and right anterior, middle, and posterior insula, and left and right hypothalamus. It was hypothesized that the profiles would be altered alongside changes in homeostatic energy balance. Nineteen healthy participants underwent two 7‐min resting state functional magnetic resonance imaging scans, one when fasted and one when satiated. Functional connectivity between the left posterior insula and cerebellum/superior frontal gyrus, and between left hypothalamus and inferior frontal gyrus was stronger during fasting. Functional connectivity between the right middle insula and default mode structures (left and right posterior parietal cortex, cingulate cortex), and between right hypothalamus and superior parietal cortex was stronger during satiation. Differences in blood glucose levels between the scans accounted for several of the altered functional connectivities. The insula and hypothalamus appear to form a homeostatic energy balance network related to cognitive control of eating; prompting eating and preventing overeating when energy is depleted, and ending feeding or transferring attention away from food upon satiation. This study provides evidence of a lateralized dissociation of neural responses to energy modulations.

Influence of Nutrition Claims on Appetite Sensations according to Sex, Weight Status, and Restrained Eating

Nutrition claims may help people to adopt healthier eating habits, but little is known about the potential cognitive effects of such claims on appetite sensations. The main purpose of this study was to evaluate the impact of nutrition claims and individual factors on perceived appetite sensations. According to a three ("healthy" versus "diet" (i.e., satiating) versus "hedonic") by two (restrained or not restrained) by two (normal-weight or overweight/obese) by two (men versus women) factorial design, 164 males and 188 females aged 18-65 were invited to taste an oatmeal-raisin snack in a blinded and ad libitum context. Visual analog scales (150 mm) were used to evaluate appetite sensations before and over 1 h after consumption period. BMI and Restraint Scale were used to categorize participants according to their weight and restraint status. No main condition effect was observed for any of the four appetite sensations. However, subgroups analysis revealed significant differences among specific subgroups. A main effect of sex was also observed for all appetite sensations with men reporting higher levels of desire to eat, hunger and prospective food consumption, and lower levels of fullness than women. These findings highlight the importance of considering individual characteristics in interaction when studying appetite sensations.

Altered gut and adipose tissue hormones in overweight and obese individuals: cause or consequence?

The aim of this article is to review the research into the main peripheral appetite signals altered in human obesity, together with their modifications after body weight loss with diet and exercise and after bariatric surgery, which may be relevant to strategies for obesity treatment. Body weight homeostasis involves the gut–brain axis, a complex and highly coordinated system of peripheral appetite hormones and centrally mediated neuronal regulation. The list of peripheral anorexigenic and orexigenic physiological factors in both animals and humans is intimidating and expanding, but anorexigenic glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY (PYY) and orexigenic ghrelin from the gastrointestinal tract, pancreatic polypeptide (PP) from the pancreas and anorexigenic leptin from adiposites remain the most widely studied hormones. Homeostatic control of food intake occurs in humans, although its relative importance for eating behaviour is uncertain, compared with social and environmental influences. There are perturbations in the gut–brain axis in obese compared with lean individuals, as well as in weight-reduced obese individuals. Fasting and postprandial levels of gut hormones change when obese individuals lose weight, either with surgical or with dietary and/or exercise interventions. Diet-induced weight loss results in long-term changes in appetite gut hormones, postulated to favour increased appetite and weight regain while exercise programmes modify responses in a direction expected to enhance satiety and permit weight loss and/or maintenance. Sustained weight loss achieved by bariatric surgery may in part be mediated via favourable changes to gut hormones. Future work will be necessary to fully elucidate the role of each element of the axis, and whether modifying these signals can reduce the risk of obesity.

Postprandial effects of consuming a staggered meal on gut peptide and glycemic responses in obese women and men

Eating slowly by staggering a meal may reduce energy intake. Our aim was to examine the effect of eating a portion of beans 15min before the rest of the meal, on gastrointestinal (GI) peptides, glucose and insulin concentrations and subsequent energy intake in obese adults. This was a randomised crossover design study with 28 obese subjects. Participants consumed a standardised breakfast on test days followed by test meals: (1) control meal containing 86g (0.5 cup) of beans, and (2) staggered meal in which 86g (0.5 cup) of beans were consumed 15min before the rest of the meal. Blood obtained prior to and at 30, 60, and 120min following the meals was analysed for acylated ghrelin, unacylated ghrelin, glucagon-like peptide-1 (GLP-1), peptide YY, oxyntomodulin, glucose and insulin. Feelings of hunger and satiety were assessed using analog visual scales. Energy intake following the test meal was obtained by computer assisted dietary recalls. Mixed model statistical analysis of data showed time effects for unacylated ghrelin, GLP-1, glucose, insulin, hunger and fullness, however, meal effects were not shown for any of the parameters. GLP-1 area under the curve from baseline to 120min (AUC0-120) decreased by 19% (P=0.024) and that of glucose increased by 7% (P=0.046) following the staggered compared to the control bean meal. Energy intake subsequent to the test meals did not differ between treatments. In conclusion, lengthening meal times by staggering eating did not benefit hormonal, metabolic or appetite control in obese individuals.

Responses in gut hormones and hunger to diets with either high protein or a mixture of protein plus free amino acids supplied under weight-loss conditions

High-protein diets are an effective means for weight loss (WL), but the mechanisms are unclear. One hypothesis relates to the release of gut hormones by either protein or amino acids (AA). The present study involved overweight and obese male volunteers (n 18, mean BMI 36·8 kg/m2) who consumed a maintenance diet for 7 d followed by fully randomised 10 d treatments with three iso-energetic WL diets, i.e. with either normal protein (NP, 15% of energy) or high protein (HP, 30%) or with a combination of protein and free AA, each 15% of energy (NPAA). Psychometric ratings of appetite were recorded hourly. On day 10, plasma samples were taken at 30 min intervals over two consecutive 5 h periods (covering post-breakfast and post-lunch) and analysed for AA, glucose and hormones (insulin, total glucose-dependent insulinotropic peptide, active ghrelin and total peptide YY (PYY)) plus leucine kinetics (first 5 h only). Composite hunger was 16% lower for the HP diet than for the NP diet (P<0·01) in the 5 h period after both meals. Plasma essential AA concentrations were greatest within 60 min of each meal for the NPAA diet, but remained elevated for 3-5 h after the HP diet. The three WL diets showed no difference for either fasting concentrations or the postprandial net incremental AUC (net AUCi) for insulin, ghrelin or PYY. No strong correlations were observed between composite hunger scores and net AUCi for either AA or gut peptides. Regulation of hunger may involve subtle interactions, and a range of signals may need to be integrated to produce the overall response.

The role of glucagon-like peptide-1 impairment in obesity and potential therapeutic implications

The hormone glucagon-like peptide-1 (GLP-1) is released from the gut in response to food intake. It acts as a satiety signal, leading to reduced food intake, and also as a regulator of gastric emptying. Furthermore, GLP-1 functions as an incretin hormone, stimulating insulin release and inhibiting glucagon secretion from the pancreas in response to food ingestion. Evidence suggests that the action or effect of GLP-1 may be impaired in obese subjects, even in those with normal glucose tolerance. GLP-1 impairment may help explain the increased gastric emptying and decreased satiety signalling seen in obesity. Incretin impairment, probably associated with reduced insulinotropic potency of GLP-1, is also characteristic of type 2 diabetes (T2D). Therefore, it is possible that incretin impairment may contribute to the pathophysiological bridge between obesity and T2D. This review summarises current knowledge about the pathophysiology and consequences of GLP-1 and incretin impairment in obesity, and examines the evidence for an incretin-related link between obesity and T2D. It also considers the current literature surrounding the novel use of GLP-1 receptor agonists as a treatment for obesity in patients with normoglycaemia, prediabetes and T2D.

Sex differences in the physiology of eating

Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.