Updating gender differences in the control of homeostatic and hedonic food intake: Implications for binge eating disorder

Food preference-based screening method for identification of effectors of substance use disorders using Caenorhabditis elegans

Substance use disorder (SUD) affects over 48 million Americans aged 12 and over. Thus, identifying novel chemicals contributing to SUD will be critical for developing efficient prevention and mitigation strategies. Considering the complexity of the actions and effects of these substances on human behavior, a high-throughput platform using a living organism is ideal. We developed a quick and easy screening assay using Caenorhabditis elegans. C. elegans prefers high-quality food (Escherichia coli HB101) over low-quality food (Bacillus megaterium), with a food preference index of approximately 0.2, defined as the difference in the number of worms at E. coli HB101 and B. megaterium over the total worm number. The food preference index was significantly increased by loperamide, a μ-opioid receptor (MOPR) agonist, and decreased by naloxone, a MOPR antagonist. These changes depended on npr-17, a C. elegans homolog of opioid receptors. In addition, the food preference index was significantly increased by arachidonyl-2'-chloroethylamide, a cannabinoid 1 receptor (CB1R) agonist, and decreased by rimonabant, a CB1R inverse agonist. These changes depended on npr-19, a homolog of CB1R. These results suggest that the conserved opioid and endocannabinoid systems modulate the food preference behaviors of C. elegans. Finally, the humanoid C. elegans strains where npr-17 was replaced with human MOPR and where npr-19 was replaced with human CB1R phenocopied the changes in food preference by the drug treatment. Together, the current results show that this method can be used to rapidly screen the potential effectors of MOPR and CB1R to yield results highly translatable to humans.

Decoding the influence of central LEAP2 on food intake and its effect on accumbal dopamine release

The gut-brain peptide ghrelin and its receptor are established as a regulator of hunger and reward-processing. However, the recently recognized ghrelin receptor inverse agonist, liver-expressed antimicrobial peptide 2 (LEAP2), is less characterized. The present study aimed to elucidate LEAP2s central effect on reward-related behaviors through feeding and its mechanism. LEAP2 was administrated centrally in mice and effectively reduced feeding and intake of palatable foods. Strikingly, LEAP2s effect on feeding was correlated to the preference of the palatable food. Further, LEAP2 reduced the rewarding memory of high preference foods, and attenuated the accumbal dopamine release associated with palatable food exposure and eating. Interestingly, LEAP2 was widely expressed in the brain, and particularly in reward-related brain areas such as the laterodorsal tegmental area (LDTg). This expression was markedly altered when allowed free access to palatable foods. Accordingly, infusion of LEAP2 into LDTg was sufficient to transiently reduce acute palatable food intake. Taken together, the present results show that central LEAP2 has a profound effect on dopaminergic reward signaling associated with food and affects several aspects of feeding. The present study highlights LEAP2s effect on reward, which may have applications for obesity and other reward-related psychiatric and neurological disorders.

Longitudinal study of the impact of the COVID-19 pandemic on diet and physical activity among Latinos of Mexican ancestry

BACKGROUND

The COVID-19 pandemic caused societal disruption in the United States and most of the world, affecting many aspects of life, including healthcare and health-related behaviors such as diet, food security, and physical activity. Communities with economic and health disparities may have been particularly affected. This study was undertaken to determine how conditions in the early pandemic (January, 2021-February, 2022) affected Latino patients of Mexican Ancestry at high risk of type 2 diabetes mellitus who participated in El Banco por Salud biobank project in Tucson, Arizona.

METHODS

Baseline, prepandemic measurements were available in 17, 21, and 60 patients with normal hemoglobin A1c (HbA1c), prediabetes, and type 2 diabetes, respectively.

RESULTS

People with healthy HbA1c were significantly younger, less obese, and had higher HDL cholesterol. HbA1c was unaffected by the pandemic in any group. Triglycerides, total and HDL cholesterol levels fell in all groups during the pandemic. Physical activity levels in all groups were remarkably low, with most reporting no engagement in any voluntary physical activity. Engagement in physical activity or its enjoyment was lower in patients with diabetes and prediabetes than in younger, less obese patients. Major diet differences were between men and women and were present before the pandemic. Women consumed significantly more vegetables, fruit, and salad than men. The only pandemic-related change in diet was a drop in egg consumption, possibly explaining the fall in total cholesterol.

CONCLUSION

Societal disruption during the COVID-19 pandemic had minimal effects on adverse health-related behaviors, cardiometabolic risk, or changes in glycemic control in a Latino community with diabetes and healthcare disparities in the Southwest US.

Obesity: a gender-view

PURPOSE

There is a growing awareness of the importance of understanding gender differences in obesity. The aim of this short review was to revise the current evidence on anthropometric characteristics and nutritional and pharmacological aspects of obesity from a gender perspective.

METHODS

A literature search within PubMed was performed. Selected publications related to obesity and gender differences were reviewed.

RESULTS

The prevalence of obesity among men is higher than in women, but women have a higher percentage of body fat content compared to men, and gender appears to be an important factor in the manifestation of central (android) or peripheral (gynoid) obesity. In addition, while in most clinical trials, women are still underrepresented, in clinical registration trials of anti-obesity drugs, women are commonly up-represented and gender-specific analysis is uncommon. Considering that adipose tissue is one of the factors affecting the volume of distribution of many drugs, mainly lipophilic drugs, gender differences might be expected in the pharmacokinetics and pharmacodynamics of anti-obesity drugs. Indeed, although Liraglutide 3 mg, a long-acting glucagon-like peptide-1 receptor agonist, and naltrexone/bupropion display lipophilic properties, currently, a gender-dose adjustment for both these drugs administration is not recommended. In addition, despite that predicted responders to treatment offer substantial opportunities for efficient use, especially of expensive new therapies, such as anti-obesity drugs, data on gender differences to identify early responders to both these have not yet been investigated. Finally, bariatric surgery gender disparity reflects healthcare practices. Weight loss similar, but differing effects: women need more correction and face psychology challenges; men have worse physiology and fewer comorbidity improvements.

CONCLUSION

Gender differences exist in obesity prevalence and phenotype, body fat distribution, drug efficacy, clinical trial representation, and different secondary effects of bariatric surgery. Gender is an important variable in obesity analysis.

The transplantation of the gut microbiome of fat-1 mice protects against colonic mucus layer disruption and endoplasmic reticulum stress induced by high fat diet

High-fat diets alter gut barrier integrity, leading to endotoxemia by impacting epithelial functions and inducing endoplasmic reticulum (ER) stress in intestinal secretory goblet cells. Indeed, ER stress, which is an important contributor to many chronic diseases such as obesity and obesity-related disorders, leads to altered synthesis and secretion of mucins that form the protective mucus barrier. In the present study, we investigated the relative contribution of omega-3 polyunsaturated fatty acid (PUFAs)-modified microbiota to alleviating alterations in intestinal mucus layer thickness and preserving gut barrier integrity. Male fat-1 transgenic mice (exhibiting endogenous omega-3 PUFAs tissue enrichment) and wild-type (WT) littermates were fed either an obesogenic high-fat diet (HFD) or a control diet. Unlike WT mice, HFD-fed fat-1 mice were protected against mucus layer alterations as well as an ER stress-mediated decrease in mucin expression. Moreover, cecal microbiota transferred from fat-1 to WT mice prevented changes in the colonic mucus layer mainly through colonic ER stress downregulation. These findings highlight a novel feature of the preventive effects of omega-3 fatty acids against intestinal permeability in obesity-related conditions.

Sport and exercise medicine/physiotherapy publishing has a gender/sex equity problem: we need action now!

OBJECTIVES

We aimed to determine (1) the proportion of women authors overall, in first (lead) and last (senior) author positions, (2) the proportion of women research participants and (3) the association between women in first and/or last author positions and the proportion of women research participants in original research articles and editorials/opinion pieces in four sport and exercise medicine/physiotherapy journals.

METHODS

The journals evaluated were the British Journal of Sports Medicine, Journal of Orthopaedic and Sports Physical Therapy, Physical Therapy in Sport and International Journal of Sports Physical Therapy.We reviewed all original research articles and editorials/opinion pieces published in 2008, 2009, 2018 and 2019. For each, we aimed to determine the gender/sex of all authors (through gender pronouns, Google Scholar, ResearchGate, institutional profiles, personal websites, photographs and/or social media), and the gender/sex of study participants reported as 'female' or 'male' or 'women' or 'men' or 'girls' or 'boys'.

RESULTS

We included 952 original studies and 219 editorials/opinion pieces. There were 5146 authors of original studies and 706 authors of editorials/opinion pieces. Compared with 2008/2009, the proportion of women as first and last authors was 3.6% (33.0% compared with 29.4%) and 4.8% (33.2% compared with 27.4%) higher respectively in 2018/2019. On average, the proportion of women participants in original studies remained largely unchanged over the 10-year period, only 10% of all participants were women in studies.

CONCLUSION

Women are strikingly under-represented in first and last author positions, as are women participants in sports and exercise medicine/physiotherapy journals.

Sex differences in neuroimmunoendocrine communication. Involvement on longevity

Endocrine, nervous, and immune systems work coordinately to maintain the global homeostasis of the organism. They show sex differences in their functions that, in turn, contribute to sex differences beyond reproductive function. Females display a better control of the energetic metabolism and improved neuroprotection and have more antioxidant defenses and a better inflammatory status than males, which is associated with a more robust immune response than that of males. These differences are present from the early stages of life, being more relevant in adulthood and influencing the aging trajectory in each sex and may contribute to the different life lifespan between sexes.

Habitual behaviour associated with exposure to high-calorie diet is prevented by an orexin-receptor-1 antagonist

Habitual actions, which are associated with addictive behaviours, contribute to the loss of control of food seeking seen following exposure to calorie-dense foods in rats. Antagonism of orexin-receptor-1 (ORX-R1) has been shown to reduce a range of stimulus-driven feeding behaviours, but have yet to be implicated in the regulation of habitual actions. In the current study, male Long-Evans rats were given 'binge-like' access to high-calorie diet (HCD) or standard chow diet, and were subsequently trained to press a lever for food outcome. When lever responses were tested following outcome devaluation, chow-fed rats displayed goal-directed actions, whereas HCD-exposed rats displayed habitual actions. In study 1, it was shown that systemic administration of the ORX-R1 antagonist, SB-334867, prior to test restored goal-directed behaviour in HCD-exposed rats. In study 2, intra-nigral administration of SB-334867 similarly restored goal-directed behaviour, thereby implicating the substantia nigra as an important site for this effect. This study demonstrates that targeting ORX-R1 reduces habitual food seeking in male rats which may be important for understanding and treating compulsive feeding, obesity and binge eating disorder. This study also implicates the lateral hypothalamus, where ORX is produced, in mediating the expression of habits for the first time, and thus extends on the neurocircuits known to regulate habitual actions. Further investigation is required to determine whether the same effects are also seen in female rats, given that there are recognised sexual dimorphisms in feeding behaviour and a higher incidence of disordered eating in female than male populations.

A Tailored Gender-Sensitive mHealth Weight Loss Intervention (I-GENDO): Development and Process Evaluation

BACKGROUND

Given the increase in the prevalence of overweight and obesity worldwide, the number of digital weight loss interventions has also risen. However, these interventions often lack theoretical background and data on long-term effectiveness. The consideration of individual and gender differences in weight-related psychological parameters might enhance the efficacy and sustainability of mobile-based weight loss interventions.

OBJECTIVE

This paper presented an introduction to and the process evaluation of a 12-week gender-sensitive mobile health (mHealth) weight loss intervention (I-GENDO) combining computer-based and self-tailoring features.

METHODS

Between August 2020 and August 2021, individuals with overweight (BMI 25.0-29.9 kg/m²), those with obesity class I (BMI 30.0-34.9 kg/m²), and those with obesity class II (BMI 35.0-39.9 kg/m²) were recruited to the I-GENDO project, a multicenter study in Germany. The mHealth intervention aimed at targeting individual psychological factors associated with the development and persistence of overweight and obesity (eg, emotional eating) using computer-based tailoring. Moreover, the intervention took a gender-sensitive approach by implementing self-tailoring of gender-targeted module versions. The computer-based assignment of the main modules, self-selection of gender-targeted module versions, and use patterns were evaluated while considering gender. Moreover, gender differences in the usability assessment were analyzed.

RESULTS

Data from the intervention arm of the study were processed. A total of 116 individuals with overweight and obesity (77/116, 66.4% women; age mean 47.28, SD 11.66 years; BMI mean 33.58, SD 3.79 kg/m2) were included in the analyses. Overall, the compliance (90/109, 82.6%) and satisfaction with the app (mean 86% approval) were high and comparable with those of other mobile weight loss interventions. The usability of the intervention was rated with 71% (5.0/7.0 points) satisfaction. More women obtained the main module that focused on emotion regulation skills. Most men and women selected women-targeted versions of the main modules. Women used the app more frequently and longer than men. However, women and men did not differ in the progress of use patterns throughout the intervention.

CONCLUSIONS

We developed a tailored gender-sensitive mHealth weight loss intervention. The usability of and engagement with the intervention were satisfactory, and the overall satisfaction with the intervention was also high. Gender differences must be considered in the evaluation of the effectiveness and sustainability of the intervention.

The relationship of hedonic hunger with food addiction and obesity in university students

PURPOSE

In this study, it was aimed to evaluate the relationship of hedonic hunger with food addiction and obesity in university students.

METHODS

The research sample consists of 275 university students between the ages of 19-28 years. Body weight (kg), height (cm), waist and hip circumference (cm) were measured by applying a face-to-face questionnaire including descriptive characteristics of individuals, the Power of Food Scale (PFS), the Palatable Eating Motive Scale (PEMS) and the Modified Yale Food Addiction Scale (mYFAS) 2.0. Statistical analysis of the data was done with SPSS (Statistical Package for Social Sciences) 18.

RESULTS

In individuals, according to the mean PFS score the presence of food power-induced hedonic hunger was detected. While according to the mean PEMS score no motivational hedonic hunger was detected. According to the BMI classification the average scores of PFS (p = 0.002), PEMS (p = 0.009), and mYFAS 2.0 (p < 0.001) showed a gradual increase from underweight to obese. A weak positive correlation was found between BMI and PFS score (r = 0.238; p < 0.05) and PEMS score (r = 0.196; p < 0.05), respectively. The moderate positive correlation (r = 0.439 p < 0.001) was found between mYFAS 2.0 and the PEMS scores.

CONCLUSION

As a result, the presence of food-based hedonic hunger was determined in young individuals. A relationship was determined between food addiction and hedonic hunger caused by the motivation to consume delicious foods. Accordingly, hedonic hunger is related to food addiction and obesity in university students.

LEVEL OF EVIDENCE

V, cross-sectional descriptive study.

Ghrelin deficiency sex-dependently affects food intake, locomotor activity, and adipose and hepatic gene expression in a binge-eating mouse model

Binge-eating disorder is the most prevalent eating disorder diagnosed, affecting three times more women than men. Ghrelin stimulates appetite and reward signaling, and loss of its receptor reduces binge-eating behavior in male mice. Here, we examined the influence of ghrelin itself on binge-eating behavior in both male and female mice. Five-wk-old wild-type (WT) and ghrelin-deficient (Ghrl^-/-) mice were housed individually in indirect calorimetry cages for 9 wks. Binge-like eating was induced by giving mice ad libitum chow, but time-restricted access to a Western-style diet (WD; 2 h access, 3 days/wk) in the light phase (BE); control groups received ad libitum chow (CO), or ad libitum access to both diets (CW). All groups of BE mice showed binge-eating behavior, eating up to 60% of their 24-h intake during the WD access period. Subsequent dark phase chow intake was decreased in Ghrl^-/- mice and remained decreased in Ghrl^-/- females on nonbinge days. Also, nonbinge day locomotor activity was lower in Ghrl^-/- than in WT BE females. Upon euthanasia, Ghrl^-/- BE mice weighed less and had a lower lean body mass percentage than WT BE mice. In BE and CW groups, ghrelin and sex altered the expression of genes involved in lipid processing, thermogenesis, and aging in white adipose tissue and livers. We conclude that, although ghrelin deficiency does not hamper the development of binge-like eating, it sex-dependently alters food intake timing, locomotor activity, and metabolism. These results add to the growing body of evidence that ghrelin signaling is sexually dimorphic.NEW & NOTEWORTHY Ghrelin, a peptide hormone secreted from the gut, is involved in hunger and reward signaling, which are altered in binge-eating disorder. Although sex differences have been described in both binge-eating and ghrelin signaling, this interaction has not been fully elucidated. Here, we show that ghrelin deficiency affects the behavior and metabolism of mice in a binge-like eating paradigm, and that the sex of the mice impacts the magnitude and direction of these effects.

Association between Visceral Adiposity Index, Binge Eating Behavior, and Grey Matter Density in Caudal Anterior Cingulate Cortex in Severe Obesity

Visceral adipose tissue accumulation is an important determinant of metabolic risk and can be estimated by the visceral adiposity index (VAI). Visceral adiposity may impact brain regions involved in eating behavior. We aimed to examine the association between adiposity measurements, binge eating behavior, and grey matter density. In 20 men and 59 women with severe obesity, Grey matter density was measured by voxel-based morphometry for six regions of interest associated with reward, emotion, or self-regulation: insula, orbitofrontal cortex, caudal and rostral anterior cingulate cortex (ACC), ventromedial prefrontal cortex (vmPFC), and dorsolateral prefrontal cortex (DLPFC). Binge eating behavior, depression and impulsivity was assessed by the Binge Eating Scale, Beck Depression Inventory and UPPS Impulsive Behavior Scale, respectively. Men and women were distinctively divided into two subgroups (low-VAI and high-VAI) based on the mean VAI score. Women with high-VAI were characterized by metabolic alterations, higher binge eating score and lower grey matter density in the caudal ACC compared to women with low-VAI. Men with high-VAI were characterized by a higher score for the sensation-seeking subscale of the UPPS–Impulsive Behavior Scale compared to men with low-VAI. Using a moderation–mediation analysis, we found that grey matter density in the caudal ACC mediates the association between VAI and binge eating score. In conclusion, visceral adiposity is associated with higher binge eating severity in women. Decreased grey matter density in the caudal ACC, a region involved in cognition and emotion regulation, may influence this relationship.

Decoding the Role of Gut-Microbiome in the Food Addiction Paradigm

Eating behaviour is characterised by a solid balance between homeostatic and hedonic regulatory mechanisms at the central level and highly influenced by peripheral signals. Among these signals, those generated by the gut microbiota have achieved relevance in recent years. Despite this complex regulation, under certain circumstances eating behaviour can be deregulated becoming addictive. Although there is still an ongoing debate about the food addiction concept, studies agree that patients with eating addictive behaviour present similar symptoms to those experienced by drug addicts, by affecting central areas involved in the control of motivated behaviour. In this context, this review tries to summarise the main data regarding the role of the gut microbiome in eating behaviour and how a gut dysbiosis can be responsible for a maladaptive behaviour such as “food addiction”.