FTO genotype impacts food intake and corticolimbic activation

Obesity and Cardiometabolic Disease: Insights From Genetic Studies

Obesity is a highly prevalent chronic disease and major driver of both atherosclerotic heart disease and heart failure. Obesity is also a heritable neuronal disease with heritability estimates of up to 70%. In this work I review how common genetic variants, usually with small effect sizes, contribute to the risk for developing obesity and cardiometabolic disease in the majority of people and how this can be further modulated by environmental factors. In some individuals, rare genetic variants with large effect sizes can influence the risk of developing obesity, in some cases in a Mendelian manner. I also address how identification of these rare variants has led to fundamental biologic insights into how satiety and reward are biologic processes, has led to more personalized treatments, and has identified potential novel drug treatments. Biologic insights derived from genetic studies of obesity have also improved our understanding of the causal mediators between obesity and cardiovascular disease. A major limitation of studies to date is that they involved mostly people of European ancestry. Studying more diverse populations will improve our understanding of obesity and cardiometabolic disease. Lessons derived from genetic studies make a compelling case for increasing accessibility to therapies that have sustained efficacy in managing obesity and improving health. This increased knowledge must also inform public health initiatives that will reduce the prevalence of obesity in the coming decades.

A Whole Plant-Foods Diet in the Prevention and Treatment of Overweight and Obesity: From Empirical Evidence to Potential Mechanisms

Excess body adiposity, referred to as overweight and obesity, represents a major health concern given that it increases the risk of various diseases, including cardiovascular diseases, type 2 diabetes, and cancer. Body weight reduction can be achieved via a wide variety of dietary strategies as long as an energy deficit is achieved. However, the effect of such diets on disease risk and mortality will depend on the foods included. Increasing evidence shows that consumption of whole plant foods (e.g., fruits, vegetables, whole grains, nuts, seeds, legumes) in place of animal foods (e.g., meat, poultry, dairy, fish, eggs, and seafood and their derivatives) and non-whole plant foods (e.g., refined grains, French fries, sugar-sweetened beverages) is associated with improvements in cardiometabolic risk factors and lower risk of chronic diseases and mortality. This review focuses on the effect of a whole plant-foods diet on overweight and obesity from observational to clinical studies and discusses the potential mechanisms involved. According to existing evidence, a whole plant foods diet seems to be more advantageous than other dietary approaches for the prevention and treatment of excess adiposity given that it is composed of the foods that lead to the best health outcomes.

Exploring associations between the FTO rs9939609 genotype and plasma concentrations of appetite-related hormones in adults with obesity

Associations between variants in the FTO locus and plasma concentrations of appetite related hormones are inconsistent, and might not work in a dose dependent fashion in people with obesity. Moreover, it is relevant to report meal related plasma concentrations of these hormones in persons with obesity given the growing interest in their pharmacological potential in obesity therapy. We find it clinically relevant to examine associations between the SNP rs9939609 genotypes and homeostatic appetite regulation in individuals with BMI ≥35 kg/m2. This study explored associations of the rs9939609 genotypes to plasma concentrations of acylated ghrelin, active glucagon-like peptide 1 (GLP-1), and total peptide YY (PYY), and moderating effects of fat mass (FM), in 96 adults (69% female) with BMI ≥35 kg/m2, using a cross sectional observation study designed to have 1/3 of participants each with genotypes TT, AT and AA, respectively. Participants were median (25th, 75th percentile) 42.5 (32, 50) years of age, weighed 120.9 (109.6, 142.4) kg, and had a BMI of 42.8 (39.5, 46.4) kg/m2. Acylated ghrelin, active GLP-1, and total PYY were measured in the fasted state and half-hourly for 2.5h after a standardized meal. We evaluated associations between genotype and appetite hormones in regression analysis controlling for FM and sex. Genotype did not associate with fasting or postprandial (area under curve, AUC) GLP-1 or PYY. Genotype did not associate with fasting acylated ghrelin, but in females with genotype AA, increased FM was associated with higher fasting and postprandial (AUC) acylated ghrelin concentrations relative to genotypes TT (fasting p = 0.025; AUC p = 0.004) and AT (fasting p = 0.002; AUC p < 0.001). This novel finding warrants further investigation.

Association of FTO variants rs9939609 and rs1421085 with elevated sugar and fat consumption in adult obesity

This cross-sectional study explores the impact of FTO gene single nucleotide polymorphisms (SNPs) rs9939609 and rs1421085 on dietary habits contributing to obesity risk in Thai adults. The study enrolled 384 participants from Bangkok, categorized as non-obese (BMI < 25 kg/m2) or obese (BMI ≥ 25 kg/m2) based on WHO Asia Pacific Guidelines. Genotyping for FTO variants was performed using DNA from blood samples. While both SNPs adhered to Hardy-Weinberg equilibrium, the association between risk alleles and anthropometric measurements was not statistically significant. However, risk allele carriers showed significantly higher intakes of sugar and saturated fat compared to homozygous dominant individuals. In the obese group, the odds ratio for high-sugar intake was 2.22 (95% CI 1.13-4.37, p = 0.021) for rs9939609 risk allele carriers. For high-saturated fat intake, the odds ratio was 1.86 (95% CI 1.02-3.40, p = 0.041). Similar associations were observed for rs1421085. Risk allele carriers also exhibited significantly higher leptin levels (p < 0.043) and a positive correlation with myeloperoxidase levels (p < 0.038). These findings highlight the complex relationship between FTO risk alleles, increased consumption of sugar and saturated fat, and obesity-related parameters. The insights emphasize the importance of considering both genetic and dietary factors in obesity prevention strategies.

Genes Involved in Susceptibility to Obesity and Emotional Eating Behavior in a Romanian Population

Obesity, a significant public health concern with high prevalence in both adults and children, is a complex disorder arising from the interaction of multiple genes and environmental factors. Advances in genome-wide association studies (GWAS) and sequencing technologies have identified numerous polygenic causes of obesity, particularly genes involved in hunger, satiety signals, adipocyte differentiation, and energy expenditure. This study investigates the relationship between six obesity-related genes (CLOCK, FTO, GHRL, LEP, LEPR, MC4R) and their impact on BMI, WC, HC, WHR, and emotional eating behavior in 220 Romanian adults. Emotional eating was assessed using the validated Emotional Eating Questionnaire (EEQ). Our analysis revealed significant variability in obesity-related phenotypes and emotional eating behaviors across different genotypes. Specifically, CLOCK/CC, FTO/AA, and LEP/AA genotypes were strongly associated with higher obesity metrics and emotional eating scores, while GHRL/TT and MC4R/CC were linked to increased BMI and WHR. The interplay between genetic predisposition and emotional eating behavior significantly influenced BMI and WHR, indicating a complex relationship between genetic and behavioral factors. This study, the first of its kind in Romania, provides a foundation for targeted interventions to prevent and reduce obesity and suggests potential strategies for gene expression modulation to mitigate the effects of emotional eating. Adopting a 'One Health' approach by creating an evidence base derived from both human and animal studies is crucial for understanding how to control obesity.

The interaction of the FTO gene and age interferes with macronutrient and vitamin intake in women with morbid obesity

Fat mass and obesity-related (FTO) gene single nucleotide polymorphisms (SNPs) interferes with food preferences that impact macronutrient intake. Few studies have investigated the relationship of this polymorphisms with the intake of micronutrients. Moreover, studies have shown multiple micronutrient deficiencies in patients with obesity. This work evaluated the effect of the FTO rs9939609 gene polymorphism on dietary nutritional quality and food intake of macronutrients and vitamins in of women with obesity candidates for metabolic surgery. The study included 106 women (24 to 60 years old) with BMIs of 36.1 to 64.8 kg/m2. A food frequency questionnaire validated for the local population was applied to obtain information about food intake. The Index of Nutritional Quality (INQ) was used to assess the adequacy of macronutrient and vitamin intake. Energy, protein and lipid intakes were higher in carriers of the A allele compared to TT in the younger age groups but were similar in the class of subjects aged ≥45 years. The INQ for protein was higher in carriers of the A allele than in carriers of the TT allele. The INQs for protein, carbohydrate, vitamins B2, B3 and B6 decreased, whereas the INQ for vitamin C increased with advancing age. The INQ for vitamin A was lower in AA than in TT, regardless of age, whereas vitamin E was higher in younger AA than in older AA. The INQ for vitamin B9 was higher in younger women than in older women. In conclusion, the FTO gene contributed to the intake of more energy, protein and lipids and interfered with the intake of vitamins B9, A and E. With the exception of vitamin A, the effect of the genotype was attenuated with ageing.

FTO variant is associated with changes in BMI, ghrelin, and brain function following bariatric surgery

BACKGROUNDA polymorphism in the fat mass and obesity-associated gene (FTO) is linked to enhanced neural sensitivity to food cues and attenuated ghrelin suppression. Risk allele carriers regain more weight than noncarriers after bariatric surgery. It remains unclear how FTO variation affects brain function and ghrelin following surgery.METHODSResting-state functional magnetic resonance imaging and cue-reactivity functional magnetic resonance imaging with high-/low-caloric food cues were performed before surgery and at 1, 6, and 12 months after surgery to examine brain function in 16 carriers with 1 copy of the rs9939609 A allele (AT) and 26 noncarriers (TT). Behavioral assessments up to 5 years after surgery were also conducted.RESULTSThe AT group relative to the TT group had smaller BMI loss at 12-60 months after surgery and lower resting-state activity in posterior cingulate cortex following laparoscopic sleeve gastrectomy (group-by-time interaction effects). Meanwhile, the AT group relative to the TT group showed greater food cue responses in dorsolateral prefrontal cortex (DLPFC), dorsomedial prefrontal cortex (DMPFC), and insula (group effects). There were negative associations of weight loss with ghrelin and greater activation in DLPFC, DMPFC and insula in the AT but not the TT group.CONCLUSIONThese findings indicate that FTO variation is associated with the evolution of ghrelin signaling and brain function after bariatric surgery, which might hinder weight loss.TRIAL REGISTRATIONChinese Clinical Trial Registry Center, ChiCTR-OOB-15006346.FUNDINGThis work was supported by the National Natural Science Foundation of China (grant nos. 82172023, 82202252, 82302292); National Key R&D Program of China (no. 2022YFC3500603); Natural Science Basic Research Program of Shaanxi (grant nos. 2022JC-44, 2022JQ-622, 2023-JC-QN-0922, 2023-ZDLSF-07); Fundamental Research Funds for the Central Universities (grant nos. ZYTS23188, XJSJ23190, XJS221201, QTZX23093); and the Intramural Research Program of the National Institute on Alcoholism and Alcohol Abuse (grant no. Y1AA3009).

Risk of Fat Mass- and Obesity-Associated Gene-Dependent Obesogenic Programming by Formula Feeding Compared to Breastfeeding

It is the purpose of this review to compare differences in postnatal epigenetic programming at the level of DNA and RNA methylation and later obesity risk between infants receiving artificial formula feeding (FF) in contrast to natural breastfeeding (BF). FF bears the risk of aberrant epigenetic programming at the level of DNA methylation and enhances the expression of the RNA demethylase fat mass- and obesity-associated gene (FTO), pointing to further deviations in the RNA methylome. Based on a literature search through Web of Science, Google Scholar, and PubMed databases concerning the dietary and epigenetic factors influencing FTO gene and FTO protein expression and FTO activity, FTO's impact on postnatal adipogenic programming was investigated. Accumulated translational evidence underscores that total protein intake as well as tryptophan, kynurenine, branched-chain amino acids, milk exosomal miRNAs, NADP, and NADPH are crucial regulators modifying FTO gene expression and FTO activity. Increased FTO-mTORC1-S6K1 signaling may epigenetically suppress the WNT/β-catenin pathway, enhancing adipocyte precursor cell proliferation and adipogenesis. Formula-induced FTO-dependent alterations of the N6-methyladenosine (m6A) RNA methylome may represent novel unfavorable molecular events in the postnatal development of adipogenesis and obesity, necessitating further investigations. BF provides physiological epigenetic DNA and RNA regulation, a compelling reason to rely on BF.

Associations Between rs9939609 FTO Polymorphism With Nutrient and Food Intake and Adherence to Dietary Patterns in an Urban Argentinian Population

BACKGROUND

The A allele of rs9939609 polymorphism at the FTO gene has been consistently associated with higher body mass index in different populations, but conflicting results have been found regarding its contribution to food intake variability.

OBJECTIVE

This study aimed to investigate the association between this genetic variant and nutrient and food intake in an urban Argentinian population.

DESIGN

A cross-sectional, analytic investigation was performed between October 2018 and February 2020.

PARTICIPANTS/SETTINGS

Adults of both sexes residing in La Plata, Argentina, were recruited through social networks (Instagram and Facebook). Of 179 eligible adults, a total of 173 adults were included in the final analyses.

OUTCOME MEASURES

Nutrient and food group intake data were obtained by an interview-administered food frequency questionnaire. Height and weight were measured, and genotypes were obtained by real-time polymerase chain reaction.

STATISTICAL ANALYSES

The per-allele effect on nutrient and food group intake was assessed by general linear models, adjusting for age, sex, educational level, total energy intake, and body mass index. Dietary patterns were derived by principal component analysis. The association of the A allele with adherence to each dietary pattern was also evaluated by the general linear model.

RESULTS

The frequency of the risk allele was 27%. A-carriers showed a higher total fat (1.88 [0.55, 3.21] % of total energy intake), saturated fatty acids (0.82 [0.25-1.39] % of total energy intake), and monounsaturated fatty acids (0.66 [0.08, 1.24] % of total energy intake), and a lower carbohydrate (-1.99 [-3.48, -0.50] % of total energy intake) intake than TT homozygous. A-carriers also reported a higher "milk and yogurt" (1.08 [0.24, 1.91] % of total energy intake), "animal fats" (1.09 [0.14-2.03] % of total energy intake), and fat-rich ultraprocessed foods (2.10 [0.52, 3.67] % of total energy intake) intake in comparison with TT homozygous. Furthermore, A-carriers showed higher adherence to the Western dietary pattern.

CONCLUSION

The A allele contributed to nutrient and food intake variability in the studied population and was associated with the consumption of saturated fatty acids-enriched foods.

From the reward network to whole-brain metrics: structural connectivity in adolescents and young adults according to body mass index and genetic risk of obesity

BACKGROUND

Obesity is a multifactorial condition. Genetic variants, such as the fat mass and obesity related gene (FTO) polymorphism, may increase the vulnerability of developing obesity by disrupting dopamine signaling within the reward network. Yet, the association of obesity, genetic risk of obesity, and structural connectivity of the reward network in adolescents and young adults remains unexplored. We investigate, in adolescents and young adults, the structural connectivity differences in the reward network and at the whole-brain level according to body mass index (BMI) and the FTO rs9939609 polymorphism.

METHODS

One hundred thirty-two adolescents and young adults (age range: [10, 21] years, BMI z-score range: [-1.76, 2.69]) were included. Genetic risk of obesity was determined by the presence of the FTO A allele. Whole-brain and reward network structural connectivity were analyzed using graph metrics. Hierarchical linear regression was applied to test the association between BMI-z, genetic risk of obesity, and structural connectivity.

RESULTS

Higher BMI-z was associated with higher (B = 0.76, 95% CI = [0.30, 1.21], P = 0.0015) and lower (B = -0.003, 95% CI = [-0.006, -0.00005], P = 0.048) connectivity strength for fractional anisotropy at the whole-brain level and of the reward network, respectively. The FTO polymorphism was not associated with structural connectivity nor with BMI-z.

CONCLUSIONS

We provide evidence that, in healthy adolescents and young adults, higher BMI-z is associated with higher connectivity at the whole-brain level and lower connectivity of the reward network. We did not find the FTO polymorphism to correlate with structural connectivity. Future longitudinal studies with larger sample sizes are needed to assess how genetic determinants of obesity change brain structural connectivity and behavior.

Unraveling Adipose Tissue Dysfunction: Molecular Mechanisms, Novel Biomarkers, and Therapeutic Targets for Liver Fat Deposition

Adipose tissue (AT), once considered a mere fat storage organ, is now recognized as a dynamic and complex entity crucial for regulating human physiology, including metabolic processes, energy balance, and immune responses. It comprises mainly two types: white adipose tissue (WAT) for energy storage and brown adipose tissue (BAT) for thermogenesis, with beige adipocytes demonstrating the plasticity of these cells. WAT, beyond lipid storage, is involved in various metabolic activities, notably lipogenesis and lipolysis, critical for maintaining energy homeostasis. It also functions as an endocrine organ, secreting adipokines that influence metabolic, inflammatory, and immune processes. However, dysfunction in WAT, especially related to obesity, leads to metabolic disturbances, including the inability to properly store excess lipids, resulting in ectopic fat deposition in organs like the liver, contributing to non-alcoholic fatty liver disease (NAFLD). This narrative review delves into the multifaceted roles of WAT, its composition, metabolic functions, and the pathophysiology of WAT dysfunction. It also explores diagnostic approaches for adipose-related disorders, emphasizing the importance of accurately assessing AT distribution and understanding the complex relationships between fat compartments and metabolic health. Furthermore, it discusses various therapeutic strategies, including innovative therapeutics like adipose-derived mesenchymal stem cells (ADMSCs)-based treatments and gene therapy, highlighting the potential of precision medicine in targeting obesity and its associated complications.

Fat mass and obesity-associated (FTO) gene is essential for insulin secretion and β-cell function: In vitro studies using INS-1 cells and human pancreatic islets

AIMS

In this study, we investigated the role of the FTO gene in pancreatic β-cell biology and its association with type 2 diabetes (T2D). To address this issue, human pancreatic islets and rat INS-1 (832/13) cells were used to perform gene silencing, overexpression, and functional analysis of FTO expression; levels of FTO were also measured in serum samples obtained from diabetic and obese individuals.

RESULTS

The findings revealed that FTO expression was reduced in islets from hyperglycemic/diabetic donors compared to normal donors. This reduction correlated with decreased INS and GLUT1 expression and increased PDX1, GCK, and SNAP25 expression. Silencing of Fto in INS-1 cells impaired insulin release and mitochondrial ATP production and increased apoptosis in pro-apoptotic cytokine-treated cells. However, glucose uptake and reactive oxygen species production rates remained unaffected. Downregulation of key β-cell genes was observed following Fto-silencing, while Glut2 and Gck were unaffected. RNA-seq analysis identified several dysregulated genes involved in metal ion binding, calcium ion binding, and protein serine/threonine kinase activity. Furthermore, our findings showed that Pdx1 or Mafa-silencing did not influence FTO protein expression. Overexpression of FTO in human islets promoted insulin secretion and upregulated INS, PDX1, MAFA, and GLUT1 expression. Serum FTO levels did not significantly differ between individuals with diabetes or obesity and their healthy counterparts.

CONCLUSION

These findings suggest that FTO plays a crucial role in β-cell survival, metabolism, and function and point to a potential therapeutic utility of FTO in T2D patients.

Longitudinal effects of FTO gene polymorphism on body composition, cardiorespiratory fitness, physical activity, inflammatory markers, and cardiovascular risk in children and adolescents. "The UP & DOWN study"

The role of polymorphism rs9939609 of the FTO gene has been related with fat mass and cardiovascular risk in adults, but it remains unclear in children and adolescents. Hence, the main aim of this study was to determine the FTO polymorphism effects on body composition, cardiorespiratory fitness (CRF), physical activity (PA), inflammatory markers, and cardiovascular risk both in cross-sectional analysis and after two-years of follow-up in children and adolescents. A total of 2129 participants were included in this study. The rs9939609 polymorphism was genotyped. Body composition measurements, CRF, and moderate-to-vigorous PA (MVPA) were determined at baseline and after two-year of follow-up. Moreover, plasma leptin and adiponectin were also determined as inflammatory markers. Furthermore, an index of cardiovascular disease risk factors (CVDRF-I) was calculated. Codominant (TT vs. TA vs. AA) and dominant (AA+AT vs. TT) models were applied for statistical analysis. The results showed a main effect of the FTO genotype on body composition measures in both first and third year (p < 0.05), with lower adiposity in TT compared with AA or AA+AT group. These differences were maintained after accounting for pubertal maturity, sex, age, VO2 max, and MVPA. Moreover, lower leptin level was observed in TT compared to AA+AT group in the third year. An interaction in Gene*Time*Sex was found in height and neck circumference in dominant model (p = 0.047; p = 0.020, respectively). No differences were found in CRF, MVPA nor CVDRF-I between groups. Hence, homozygous TT allele could be a protective factor against weight gain from early childhood.

Studies on the fat mass and obesity-associated (FTO) gene and its impact on obesity-associated diseases

Obesity has become a major health crisis in the past ∼50 years. The fat mass and obesity-associated (FTO) gene, identified by genome-wide association studies (GWAS), was first reported to be positively associated with obesity in humans. Mice with more copies of the FTO gene were observed to be obese, while loss of the gene in mice was found to protect from obesity. Later, FTO was found to encode an m6A RNA demethylase and has a profound effect on many biological and metabolic processes. In this review, we first summarize recent studies that demonstrate the critical roles and regulatory mechanisms of FTO in obesity and metabolic disease. Second, we discuss the ongoing debates concerning the association between FTO polymorphisms and obesity. Third, since several small molecule drugs and micronutrients have been found to regulate metabolic homeostasis through controlling the expression or activity of FTO, we highlight the broad potential of targeting FTO for obesity treatment. Improving our understanding of FTO and the underlying mechanisms may provide new approaches for treating obesity and metabolic diseases.

Role of rs9939506 polymorphism of FTO gene in resistance to eating in male adolescents

BACKGROUND

Single Nucleotide Polymorphisms (SNPs) of the Fat mass and obesity-associated (FTO) gene may be associated with obesity by regulating appetite. The present study aimed to investigate the relationship between FTO genotype and resistance to eating in male adolescents.

METHODS

The present cross-sectional study included 246 adolescent boys in Tehran, Iran, who were assessed for self-efficacy related to weight control using the Weight Efficacy Lifestyle (WEL), questionnaire, food intake using the Food Frequency Questionnaire (FFQ), physical activity using the International Physical Activity Questionnaire (IPAQ), and anthropometric indices using Bio-Impedance Analyzer (BIA). Moreover, the participants underwent genotyping for the rs9930506 polymorphism of the FTO gene, and the relationship between FTO genotype and resistance to eating was investigated using different models of multiple linear regression.

RESULTS

According to our findings, there was a significant reverse relationship between the FTO rs9930506 genotype and resistance to eating (β: -0.16, P = 0.01). Moreover, the relationship was still significant after adjusting for age, nutritional knowledge, BMI, and mother's BMI, educational level, and occupational status.

CONCLUSION

According to our results, the FTO genotype had a significant effect on resistance to eating and food desires. However, there is a need for further studies to evaluate the underlying mechanisms of the effects of the FTO gene on appetite and obesity.

Preclinical Models of Chronic Stress: Adaptation or Pathology?

The experience of prolonged stress changes how individuals interact with their environment and process interoceptive cues, with the end goal of optimizing survival and well-being in the face of a now-hostile world. The chronic stress response includes numerous changes consistent with limiting further damage to the organism, including development of passive or active behavioral strategies and metabolic adjustments to alter energy mobilization. These changes are consistent with symptoms of pathology in humans, and as a result, chronic stress has been used as a translational model for diseases such as depression. While it is of heuristic value to understand symptoms of pathology, we argue that the chronic stress response represents a defense mechanism that is, at its core, adaptive in nature. Transition to pathology occurs only after the adaptive capacity of an organism is exhausted. We offer this perspective as a means of framing interpretations of chronic stress studies in animal models and how these data relate to adaptation as opposed to pathology.

The Molecular and Genetic Interactions between Obesity and Breast Cancer Risk

Breast cancer (BC) is considered the leading cause of death among females worldwide. Various risk factors contribute to BC development, such as age, genetics, reproductive factors, obesity, alcohol intake, and lifestyle. Obesity is considered to be a pandemic health problem globally, affecting millions of people worldwide. Obesity has been associated with a high risk of BC development. Determining the impact of obesity on BC development risk in women by demonstrating the molecular and genetic association in pre- and post-menopause females and risk to BC initiation is crucial in order to improve the diagnosis and prognosis of BC disease. In epidemiological studies, BC in premenopausal women was shown to be protective in a certain pattern. These altered effects between the two phases could be due to various physiological changes, such as estrogen/progesterone fluctuating levels. In addition, the relationship between BC risk and obesity is indicated by different molecular alterations as metabolic pathways and genetic mutation or epigenetic DNA changes supporting a strong connection between obesity and BC risk. However, these molecular and genetic alteration remain incompletely understood. The aim of this review is to highlight and elucidate the different molecular mechanisms and genetic changes occurring in obese women and their association with BC risk and development.

Neural activation of regions involved in food reward and cognitive control in young females with anorexia nervosa and atypical anorexia nervosa versus healthy controls

Anorexia nervosa (AN) and atypical AN (AtypAN) are complex neurobiological illnesses that typically onset in adolescence with an often treatment-refractory and chronic illness trajectory. Aberrant eating behaviors in this population have been linked to abnormalities in food reward and cognitive control, but prior studies have not examined respective contributions of clinical characteristics and metabolic state. Research is needed to identify specific disruptions and inform novel intervention targets to improve outcomes. Fifty-nine females with AN (n = 34) or AtypAN (n = 25), ages 10-22 years, all ≤90% expected body weight, and 34 age-matched healthy controls (HC) completed a well-established neuroimaging food cue paradigm fasting and after a standardized meal, and we used ANCOVA models to investigate main and interaction effects of Group and Appetitive State on blood oxygenation level-dependent (BOLD) activation for the contrast of exposure to high-calorie food images minus objects. We found main effects of Group with greater BOLD activation in the dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (DLPFC), hippocampus, caudate, and putamen for AN/AtypAN versus HC groups, and in the three-group model including AN, AtypAN, and HC (sub-)groups, where differences were primarily driven by greater activation in the AtypAN subgroup versus HC group. We found a main effect of Appetitive State with increased premeal BOLD activation in the hypothalamus, amygdala, nucleus accumbens, and caudate for models that included AN/AtypAN and HC groups, and in BOLD activation in the nucleus accumbens for the model that included AN, AtypAN, and HC (sub-)groups. There were no interaction effects of Group with Appetitive State for any of the models. Our findings demonstrate robust feeding-state independent group effects reflecting greater neural activation of specific regions typically associated with reward and cognitive control processing across AN and AtypAN relative to healthy individuals in this food cue paradigm. Differential activation of specific brain regions in response to the passive viewing of high-calorie food images may underlie restrictive eating behavior in this clinical population.

Increased meso-striatal connectivity mediates trait impulsivity in FTO variant carriers

Objective

While variations in the first intron of the fat mass and obesity-associated gene (FTO, rs9939609 T/A variant) have long been identified as a major contributor to polygenic obesity, the mechanisms underlying weight gain in risk allele carriers still remain elusive. On a behavioral level, FTO variants have been robustly linked to trait impulsivity. The regulation of dopaminergic signaling in the meso-striatal neurocircuitry by these FTO variants might represent one mechanism for this behavioral alteration. Notably, recent evidence indicates that variants of FTO also modulate several genes involved in cell proliferation and neuronal development. Hence, FTO polymorphisms might establish a predisposition to heightened trait impulsivity during neurodevelopment by altering structural meso-striatal connectivity. We here explored whether the greater impulsivity of FTO variant carriers was mediated by structural differences in the connectivity between the dopaminergic midbrain and the ventral striatum.

Methods

Eighty-seven healthy normal-weight volunteers participated in the study; 42 FTO risk allele carriers (rs9939609 T/A variant, FTO ⁺ group: AT, AA) and 39 non-carriers (FTO ^- group: TT) were matched for age, sex and body mass index (BMI). Trait impulsivity was assessed via the Barratt Impulsiveness Scale (BIS-11) and structural connectivity between the ventral tegmental area/substantia nigra (VTA/SN) and the nucleus accumbens (NAc) was measured via diffusion weighted MRI and probabilistic tractography.

Results

We found that FTO risk allele carriers compared to non-carriers, demonstrated greater motor impulsivity (p = 0.04) and increased structural connectivity between VTA/SN and the NAc (p< 0.05). Increased connectivity partially mediated the effect of FTO genetic status on motor impulsivity.

Conclusion

We report altered structural connectivity as one mechanism by which FTO variants contribute to increased impulsivity, indicating that FTO variants may exert their effect on obesity-promoting behavioral traits at least partially through neuroplastic alterations in humans.

Central androgen action reverses hypothalamic astrogliosis and atherogenic risk factors induced by orchiectomy and high-fat diet feeding in male mice

Hypogonadism in males confers elevated cardiovascular disease (CVD) risk by unknown mechanisms. Recent radiological evidence suggests that low testosterone (T) is associated with mediobasal hypothalamic (MBH) gliosis, a central nervous system (CNS) cellular response linked to metabolic dysfunction. To address mechanisms linking CNS androgen action to CVD risk, we generated a hypogonadal, hyperlipidemic mouse model with orchiectomy (ORX) combined with hepatic PCSK9 overexpression. After 4 wk of high-fat, high-sucrose diet (HFHS) consumption, despite equal body weights and glucose tolerance, androgen-deficient ORX mice had a more atherogenic lipid profile and increased liver and leukocyte inflammatory signaling compared with sham-operated control mice. Along with these early CVD risk indicators, ORX markedly amplified HFHS-induced astrogliosis in the MBH. Transcriptomic analysis further revealed that ORX and high-fat diet feeding induced upregulation of inflammatory pathways and downregulation of metabolic pathways in hypothalamic astrocytes. To interrogate the role of sex steroid signaling in the CNS in cardiometabolic risk and MBH inflammation, central infusion of T and dihydrotestosterone (DHT) was performed on ORX mice. Central DHT prevented MBH astrogliosis and reduced the liver inflammatory signaling and monocytosis induced by HFHS and ORX; T had a partial protective effect. Finally, a cross-sectional study in 41 adult men demonstrated a positive correlation between radiological evidence of MBH gliosis and plasma lipids. These findings demonstrate that T deficiency in combination with a Western-style diet promotes hypothalamic gliosis concomitant with increased atherogenic risk factors and provide supportive evidence for regulation of lipid metabolism and cardiometabolic risk determinants by the CNS action of sex steroids.NEW & NOTEWORTHY This study provides evidence that hypothalamic gliosis is a key early event through which androgen deficiency in combination with a Western-style diet might lead to cardiometabolic dysregulation in males. Furthermore, this work provides the first evidence in humans of a positive association between hypothalamic gliosis and LDL-cholesterol, advancing our knowledge of CNS influences on CVD risk progression.

Technologies, strategies, and cautions when deconvoluting genome-wide association signals: FTO in focus

Genome-wide association studies have revealed a plethora of genetic variants that correlate with polygenic conditions. However, causal molecular mechanisms have proven challenging to fully define. Without such information, the associations are not physiologically useful or clinically actionable. By reviewing studies of the FTO locus in the genetic etiology of obesity, we wish to highlight advances in the field fueled by the evolution of technical and analytic strategies in assessing the molecular bases for genetic associations. Particular attention is drawn to extrapolating experimental findings from animal models and cell types to humans, as well as technical aspects used to identify long-range DNA interactions and their biological relevance with regard to the associated trait. A unifying model is proposed by which independent obesogenic pathways regulated by multiple FTO variants and genes are integrated at the primary cilium, a cellular antenna where signaling molecules that control energy balance convene.

Exploring Dietary Intake in Adults with Severe Obesity and Associations with the FTO rs9939609 Genotypes

Background

Few have studied the associations between rs9939609 genotypes in the obesity candidate locus FTO and energy and nutrient intakes and meal frequencies in adults with severe obesity. We are unaware of studies that have assessed adherence to key dietary recommendations in this population, at least in Norway. Increased knowledge of genotype associations with dietary factors could improve personalized obesity therapy.

Objectives

The present study aimed to explore how the rs9939609 genotypes associate with dietary variables and adherence to key dietary recommendations in a sample of adults with severe obesity.

Methods

A cross-sectional observation study designed to have similar numbers of participants with genotypes TT, AT, and AA included 100 patients (70% women) with median (25th, 75th percentile) age 42 (32, 50) y and BMI 42.8 (39.5, 46.4) kg/m2. We assessed intakes of food groups, energy, and macro- and micronutrients from three 24-h dietary recalls and meal frequencies. Genotype associations were analyzed using regression analyses. Reported intakes were evaluated against national diet recommendations.

Results

Using a significance level of 0.01, we found no genotype associations with energy intake, energy density, adherence to recommendations, or meal frequency but tendencies of associations with energy adjusted protein intake (AA > AT, P = 0.037; AT > TT, P = 0.064), food groups milk and cream (AT > TT, P = 0.029), and Mixed dishes (AA > TT, P = 0.039). Few participants complied with recommendations for intakes of whole grains (21%), fruits and vegetables (11%), and fish (37%); however, 67% followed the recommendation to limit added sugar. Less than 20% had recommended intakes of vitamin D and folate.

Conclusions

In our patients with severe obesity, we found tendencies of associations between the FTO rs9939609 genotypes and diet but no significant associations at the 0.01 level and below. Few met key food-based diet recommendations, suggesting that the food habits in this population pose an increased risk of nutrient deficiencies. Curr Dev Nutr 2023;xx:xx.

Differential neural reward reactivity in response to food advertising medium in children

Introduction

Food cues including food advertisements (ads) activate brain regions related to motivation and reward. These responses are known to correlate with eating behaviors and future weight gain. The objective of this study was to compare brain responses to food ads by different types of ad mediums, dynamic (video) and static (images), to better understand how medium type impacts food cue response.

Methods

Children aged 9-12 years old were recruited to complete a functional magnetic resonance imaging (fMRI) paradigm that included both food and non-food dynamic and static ads. Anatomical and functional images were preprocessed using the fMRIPrep pipeline. A whole-brain analysis and a targeted region-of-interest (ROI) analysis for reward regions (nucleus accumbens, orbitofrontal cortex, amygdala, insula, hypothalamus, ventral tegmental area, substantia nigra) were conducted. Individual neural responses to dynamic and static conditions were compared using a paired t-test. Linear mixed-effects models were then constructed to test the differential response by ad condition after controlling for age, sex, BMI-z, physical activity, and % of kcal consumed of a participant's estimated energy expenditure in the pre-load prior to the MRI scan.

Results

A total of 115 children (mean=10.9 years) completed the fMRI paradigm. From the ROI analyses, the right and left hemispheres of the amygdala and insula, and the right hemisphere of the ventral tegmental area and substantia nigra showed significantly higher responses for the dynamic food ad medium after controlling for covariates and a false discovery rate correction. From the whole-brain analysis, 21 clusters showed significant differential responses between food ad medium including the precuneus, middle temporal gyrus, superior temporal gyrus, and inferior frontal gyrus, and all regions remained significant after controlling for covariates.

Discussion

Advertising medium has unique effects on neural response to food cues. Further research is needed to understand how this differential activation by ad medium ultimately affects eating behaviors and weight outcomes.

Genetic variation rs1121980 in the fat mass and obesity-associated gene (FTO) is associated with dietary intake in Koreans

Background

Fat mass and obesity-associated gene (FTO) is a well-known gene associated with body weight and obesity risk. Recent studies have suggested that genetic variations in FTO may play a role in the regulation of food preference and consumption. However, little is known with respect to Asian populations.

Objective

This study examined whether rs1121980 C > T in FTO is associated with food intake in Koreans.

Design

This study was performed using data from the Korean Genome and Epidemiology Study (Ansan/Ansung cohort). Dietary intake was determined using the semi-food frequency questionnaire, and the FTO rs1121980 genotypes of 6,262 individuals (3,049 males and 3,213 females) were analyzed along with sex and body mass index (BMI).

Result

Genetic variation did not show a significant association with the population's energy-nutrient intake. However, female T allele carriers with BMI ≥ 25 consumed more blue fish and coffee, and their coffee creamer consumption was decisively higher than that of T allele non-carriers (P _adjusted = 0.004). In males, the presence of the T allele showed a putative association with the consumption of sweets, snacks, and coffee creamer by the BMI level.

Conclusion

The FTO rs1121980 variation was associated with a preference for foods particularly high in fat (e.g. coffee creamer, blue fish, sweets, and snacks) in Koreans; these preferences varied by sex and BMI.

FTO and Anthropometrics: The Role of Modifiable Factors

Numerous gene variants are linked to an individual's propensity to become overweight or obese. The most commonly studied gene variant is the FTO single nucleotide polymorphism. The FTO risk allele is linked with increased body mass, BMI and other lifestyle factors that may perpetuate an individual's risk for obesity. Studies assessing eating behaviors, eating preferences, nutrition interventions and other lifestyle factors were reviewed. These studies demonstrated a clear difference in eating behaviors and preferences. Lifestyle modifications including physical activity and diet were effective in weight management even in those with the risk allele.

Impaired Brain Satiety Responses After Weight Loss in Children With Obesity

CONTEXT

Obesity interventions often result in increased motivation to eat.

OBJECTIVE

We investigated relationships between obesity outcomes and changes in brain activation by visual food cues and hormone levels in response to obesity intervention by family-based behavioral treatment (FBT).

METHODS

Neuroimaging and hormone assessments were conducted before and after 24-week FBT intervention in children with obesity (OB, n = 28), or children of healthy weight without intervention (HW, n = 17), all 9- to 11-year-old boys and girls. We evaluated meal-induced changes in neural activation to high- vs low-calorie food cues across appetite-processing brain regions and gut hormones.

RESULTS

Among children with OB who underwent FBT, greater declines of BMI z-score were associated with lesser reductions after the FBT intervention in meal-induced changes in neural activation to high- vs low-calorie food cues across appetite-processing brain regions (P < 0.05), and the slope of relationship was significantly different compared with children of HW. In children with OB, less reduction in brain responses to a meal from before to after FBT was associated with greater meal-induced reduction in ghrelin and increased meal-induced stimulation in peptide YY and glucagon-like peptide-1 (all P < 0.05).

CONCLUSION

In response to FBT, adaptations of central satiety responses and peripheral satiety-regulating hormones were noted. After weight loss, changes of peripheral hormone secretion support weight loss, but there was a weaker central satiety response. The findings suggest that even when peripheral satiety responses by gut hormones are intact, the central regulation of satiety is disturbed in children with OB who significantly improve their weight status during FBT, which could favor future weight regain.

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

Altered Brain Structural Reorganization and Hierarchical Integrated Processing in Obesity

The brain receives sensory information about food, evaluates its desirability and value, and responds with approach or withdrawal. The evaluation process of food in the brain with obesity may involve a variety of neurocircuit abnormalities in the integration of internal and external information processing. There is a lack of consistency of the results extant reported for aberrant changes in the brain with obesity that prohibits key brain alterations to be identified. Moreover, most studies focus on the observation of neural plasticity of function or structure, and the evidence for functional and structural correlations in the neuronal plasticity process of obesity is still insufficient. The aims of this article are to explore the key neural structural regions and the hierarchical activity pattern of key structural nodes and evaluate the correlation between changes in functional modulation and eating behavior. Forty-two participants with obesity and 33 normal-weight volunteers were recruited. Gray matter volume (GMV) and Granger causality analysis (GCA) were performed using the DPARSF, CAT12, and DynamicBC toolbox. Compared with the normal weight group, the obesity group exhibited significantly increased GMV in the left parahippocampal gyrus (PG). The obesity group showed decreased causal inflow to the left PG from the left orbitofrontal cortex (OFC), right calcarine, and bilateral supplementary motor area (SMA). Decreased causal outflow to the left OFC, right precuneus, and right SMA from the left PG, as well as increased causal outflow to the left middle occipital gyrus (MOG) were observed in the obesity group. Negative correlations were found between DEBQ-External scores and causal outflow from the left PG to the left OFC, and DEBQ-Restraint scores and causal inflow from the left OFC to the left PG in the obesity group. Positive correlation was found between DEBQ-External scores and causal outflow from the left PG to the left MOG. These results show that the increased GMV in the PG may play an important role in obesity, which may be related to devalued reward system, altered behavioral inhibition, and the disengagement of attentional and visual function for external signals. These findings have important implications for understanding neural mechanisms in obesity and developing individual-tailored strategies for obesity prevention.

Genetic variation in satiety signaling and hypothalamic inflammation: merging fields for the study of obesity

Although obesity has been a longstanding health crisis, the genetic architecture of the disease remains poorly understood. Genome-wide association studies have identified many genomic loci associated with obesity, with genes being enriched in the brain, particularly in the hypothalamus. This points to the role of the central nervous system (CNS) in predisposition to obesity, and we emphasize here several key genes along the satiety signaling pathway involved in genetic susceptibility. Interest has also risen regarding the chronic, low-grade obesity-associated inflammation, with a growing concern toward inflammation in the hypothalamus as a precursor to obesity. Recent studies have found that genetic variation in inflammatory genes play a role in obesity susceptibility, and we highlight here several key genes. Despite the interest in the genetic variants of these pathways individually, there is a lack of research that investigates the relationship between the two. Understanding the interplay between genetic variation in obesity genes enriched in the CNS and inflammation genes will advance our understanding of obesity etiology and heterogeneity, improve genetic risk prediction analyses, and highlight new drug targets for the treatment of obesity. Additionally, this increased knowledge will assist in physician's ability to develop personalized nutrition and medication strategies for combating the obesity epidemic. Though it often seems to present universally, obesity is a highly individual disease, and there remains a need in the field to develop methods to treat at the individual level.

The FTO rs9939609 Variant Is Associated with Cardiometabolic Disease Risk and Dietary Energy Intakes in Children with Mental Health Disorders

Background

Second-generation antipsychotics (SGAs) are used to treat children for mental health disorders but in some children they cause cardiometabolic complications including weight gain and type 2 diabetes. Genetic variants can place a child at risk of developing these metabolic complications. The fat mass and obesity-associated (FTO) rs9939609 A allele has been associated with obesity and dietary energy intakes in healthy children but its relation to metabolic complications in SGA-treated children is not known.

Objectives

This study investigated the association of the FTO rs9939609 variant and SGA treatment with cardiometabolic complications and dietary intakes in children with mental health disorders.

Methods

A cross-sectional population of children (≤18 y; n = 506) with mental health disorders that were SGA-treated (n = 197) and SGA-naïve (n = 309) were recruited through the Department of Psychiatry at BC Children's Hospital. Dietary intakes were estimated using 3-d food records in a subset of children (n = 73).

Results

Genotype frequencies were not different between SGA-treated (TT genotype 42.6%, TA genotype 38.6%, AA genotype 18.8%) and SGA-naïve (TT 41.1%, TA 39.5%, AA 19.4%) children. Children with the A allele had lower BMI z-sores compared with the TT genotype (0.84 ± 1.19 compared with 1.19 ± 1.36; P = 0.005, adjusted for ethnicity). We observed an interaction between FTO genotype and SGA status on fasting glucose (P = 0.036). SGA-naïve children with the A allele had higher fasting glucose than those with the TT genotype (4.96 ± 0.35 compared with 4.81 ± 0.35 mmol/L; P = 0.001), in adjusted models (age, sex, ethnicity, and BMI z-score). This was not observed in SGA-treated children. Children with the A allele had higher daily total energy intakes compared with the TT genotype (1994 ± 619 compared with 1814 ± 484 kcal/d; P = 0.048), in adjusted models (age, sex, ethnicity, and BMI z-score); no effect of SGA-treatment was observed.

Conclusions

Our findings suggest the A allele of the FTO rs9939609 variant is associated with higher BMI in children with mental health disorders, but only in those not treated with SGAs.

Identification of the interactions between specific genetic polymorphisms and nutrient intake associated with general and abdominal obesity in middle-aged adults

BACKGROUND & AIMS

Comprehensive understanding of gene-diet interactions is necessary to establish proper dietary guidelines to prevent and manage general and abdominal obesity. We investigated the role of genetic variants and their interactions with general and abdominal obesity-associated nutrients using a largescale genome-wide association study of Korean adults.

METHODS

A total of 50,808 participants from a Korean genome and epidemiology study were included. Dietary intake was assessed using a food frequency questionnaire. Obesity was defined as a body mass index ≥25 kg/m². Abdominal obesity (AO) was defined as waist circumference ≥90 cm and 80 cm in males and females, respectively. Dietary nutrient intake was classified based on Korean Dietary Reference Intakes (DRIs). Odds ratios and 95% confidence intervals were calculated after adjusting for age, sex, exercise, smoking, alcohol drinking, total energy consumption, PC1, and PC2.

RESULTS

Among the individuals consuming fat (%) above DRI, carriers of Ca binding protein 39 (CAB39)- rs6722579 minor allele (A) have a higher risk of AO than those not carrying the SNP (odds ration [OR] = 3.73, p-value = 2.05e-07; interaction p-value = 1.80e-07). Among the individuals consuming vitamin C above DRI, carriers of carboxypeptidase Q (CPQ)- rs59465035 minor allele (T) have a lower risk of AO than those without that SNP (OR = 0.89, p-value = 1.44e-08; interaction p-value = 9.50e-06). The genetic association with obesity was stronger among individuals with a genetic variant rs4130113 near GHR gene region in those consume folate above DRI and with a genetic variant rs5760920 near CRYBB2 gene region in those consume vitamin B2 above DRI.

CONCLUSION

Our study results suggested that interactions of specific polymorphisms at loci and certain nutrients may influence obesity and abdominal obesity.

Association of FTO rs1421085 single nucleotide polymorphism with fat and fatty acid intake in Indonesian adults

Objective

Recent studies showed that genetic polymorphisms in the fat mass and obesity-associated gene (FTO) were associated with obesity and dietary intake. In this study of 71 adults in Jakarta, Indonesia, we investigated FTO rs1421085 association with body mass index (BMI), macronutrient intake, and fatty acid intake. The association was evaluated using linear regression analyses assuming co-dominant, dominant, recessive, over-dominant, and additive genetic models.

Results

Only individuals with the CC genotype had a considerably higher BMI (p < 0.001), which indicates a recessive genetic trait, but the incidence for this genotype is low (68 TT + TC vs. 3 CC). Individuals with the minor C allele had an estimated increase of fat intake by 3.45–4.06% across various genetic models (dominant: p < 0.010, over-dominant: p < 0.030, additive: p < 0.010). Subjects with TC/CC genotypes had increased dietary monounsaturated fatty acid (MUFA; 1.14%, p = 0.046) and saturated fatty acid (SAFA; 2.06%, p = 0.023) intakes, compared to those with the TT genotype. In conclusion, our study provided evidence for the association between FTO rs1421085 risk allele with higher BMI and individual preferences for consuming more fat, MUFA, and SAFA. This study highlights the important role of FTO gene in food preference, and its influence on body weight.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05823-1.

The interaction between genetic polymorphisms in FTO, MC4R and MTHFR genes and adherence to the Mediterranean Diet in relation to obesity

AIMS

To investigate the potential interaction between genetic background and adherence to the Mediterranean Diet, macronutrient intake and physical activity with regard to obesity in a sample of healthy adults.

DESIGN

Cross-sectional epidemiological study including 392 adults living in the Mediterranean basin. Data including FFQ, IPAQ and sociodemographic questionnaires were collected via face-to-face interviews. Anthropometric measures were performed and saliva swab for DNA extraction. Two MD scores were calculated to assess the adherence of the population to this pattern. Three single nucleotid polymorphisms (SNPs) related to obesity were studied: FTO, MC4R, MTHFR.

FINDINGS

FTO rs9939609 is significantly associated with WHR, and MC4R with all phenotypic traits linked to obesity (BMI, WC and WHR). However, MTHFR polymorphism didn't show any significant correlation with anthropometric parameters. Adherence to the MD and high level of physical activity do not seem to protect against the occurrence of overweight and obesity in genetically predisposed subjects.

CONCLUSION

Classic lifestyle interventions are insufficient in addressing the challenging obesity pandemic. Identifying more genetic variants and understanding their interaction with lifestyle will improve the clinical outcome of these variants for risk prediction and personalized nutrition and medical therapy. Also, the MD should undergo a redefinition adapted to each country on the Mediterranean basin in order to organize public health measures for its comeback.

Linking the FTO obesity rs1421085 variant circuitry to cellular, metabolic, and organismal phenotypes in vivo

Variants in FTO have the strongest association with obesity; however, it is still unclear how those noncoding variants mechanistically affect whole-body physiology. We engineered a deletion of the rs1421085 conserved cis-regulatory module (CRM) in mice and confirmed in vivo that the CRM modulates Irx3 and Irx5 gene expression and mitochondrial function in adipocytes. The CRM affects molecular and cellular phenotypes in an adipose depot-dependent manner and affects organismal phenotypes that are relevant for obesity, including decreased high-fat diet-induced weight gain, decreased whole-body fat mass, and decreased skin fat thickness. Last, we connected the CRM to a genetically determined effect on steroid patterns in males that was dependent on nutritional challenge and conserved across mice and humans. Together, our data establish cross-species conservation of the rs1421085 regulatory circuitry at the molecular, cellular, metabolic, and organismal level, revealing previously unknown contextual dependence of the variant's action.

Reassessing relationships between appetite and adiposity in people at risk of obesity: A twin study using fMRI

BACKGROUND

Neuroimaging studies suggest that appetitive drive is enhanced in obesity.

OBJECTIVE

To test if appetitive drive varies in direct proportion to the level of body adiposity after accounting for genetic factors that contribute to both brain response and obesity risk.

SUBJECTS/METHODS

Participants were adult monozygotic (n = 54) and dizygotic (n = 30) twins with at least one member of the pair with obesity. Body composition was assessed by dual-energy X-ray absorptiometry. Hormonal and appetite measures were obtained in response to a standardized meal that provided 20% of estimated daily caloric needs and to an ad libitum buffet meal. Pre- and post-meal functional magnetic resonance imaging (fMRI) assessed brain response to visual food cues in a set of a priori appetite-regulating regions. Exploratory voxelwise analyses outside a priori regions were performed with correction for multiple comparisons.

RESULTS

In a group of 84 adults, the majority with obesity (75%), body fat mass was not associated with hormonal responses to a meal (glucose, insulin, glucagon-like peptide-1 and ghrelin, all P>0.40), subjective feelings of hunger (β=-0.01 mm [95% CI -0.35, 0.34] P = 0.97) and fullness (β=0.15 mm [-0.15, 0.44] P = 0.33), or buffet meal intake in relation to estimated daily caloric needs (β=0.28% [-0.05, 0.60] P = 0.10). Body fat mass was also not associated with brain response to high-calorie food cues in appetite-regulating regions (Pre-meal β=-0.12 [-0.32, 0.09] P = 0.26; Post-meal β=0.18 [-0.02, 0.37] P = 0.09; Change by a meal β=0.29 [-0.02, 0.61] P = 0.07). Conversely, lower fat mass was associated with being weight reduced (β=-0.05% [-0.07, -0.03] P<0.001) and greater pre-meal activation to high-calorie food cues in the dorsolateral prefrontal cortex (Z = 3.63 P = 0.017).

CONCLUSIONS

In a large study of adult twins, the majority with overweight or obesity, the level of adiposity was not associated with excess appetitive drive as assessed by behavioral, hormonal, or fMRI measures.

Dietary Patterns and Their Associations With the FTO and FGF21 Gene Variants Among Emirati Adults

Purpose: To examine the dietary patterns and their associations with the FTO and FGF21 gene variants among Emirati adults. Methods: Using a cross-sectional design, healthy adult male and female Emiratis (n = 194) were recruited from primary health care centers in Sharjah, UAE. Participants completed a 61-item semi-quantitative food frequency questionnaire. In addition, a saliva sample was obtained for the genetic analysis. Genotyping was performed for FTOrs9939609(A>T), FTOrs9930506(A>G), FGF21 rs838133 (A > G), and FGF21 rs838145 (A > G). Dietary patterns were derived using the principal component analysis. Logistic regression analyses were used to examine the association of dietary patterns with genetic variants. Results: Three dietary patterns were identified: "Western": consisting of fast food, sweets, and processed meat; "Traditional Emirati" rich in vegetables, traditional Emirati-mixed-dishes and whole dairy; while whole grains, low-fat dairy, and bulgur were components of the "Prudent" pattern. Subjects carrying the A allele of the FTO rs9939609 were 2.41 times more likely to adhere to the Western pattern compared to subjects with genotype TT (OR:2.41; 95%CI:1.05-5.50). Compared with subjects with A/A, those carrying the G allele of the FTO rs9930506 were more likely to follow a Western diet (OR: 2.19; 95%CI: 1.00-4.97). Participants carrying the risk allele (A) of the FGF21 rs838133 were twice more likely to adhere to the Traditional pattern as compared to subjects with genotype GG (OR: 1.9, 95%CI: 1.01-3.57). Conclusions: The findings of this study suggested associations among specific FTO and FGF21 gene variants with dietary patterns among Emirati adults. These findings could be used to inform evidence-based targeted nutrition preventive recommendations, especially those aiming to limit intake of western type foods.

Strategies to Understand the Weight-Reduced State: Genetics and Brain Imaging

Most individuals with obesity or overweight have difficulty maintaining weight loss. The weight-reduced state induces changes in many physiological processes that appear to drive weight regain. Here, we review the use of cell biology, genetics, and imaging techniques that are being used to begin understanding why weight regain is the normal response to dieting. As with obesity itself, weight regain has both genetic and environmental drivers. Genetic drivers for "thinness" and "obesity" largely overlap, but there is evidence for specific genetic loci that are different for each of these weight states. There is only limited information regarding the genetics of weight regain. Currently, most genetic loci related to weight point to the central nervous system as the organ responsible for determining the weight set point. Neuroimaging tools have proved useful in studying the contribution of the central nervous system to the weight-reduced state in humans. Neuroimaging technologies fall into three broad categories: functional, connectivity, and structural neuroimaging. Connectivity and structural imaging techniques offer unique opportunities for testing mechanistic hypotheses about changes in brain function or tissue structure in the weight-reduced state.

FTO Polymorphisms are Associated with Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) Susceptibility in the Older Chinese Han Population

Background

As fat and obesity play a vital role in the pathophysiology of metabolic dysfunction-associated fatty liver disease (MAFLD), this study aims to investigate the association between the fat mass and obesity-associated gene (FTO) and MAFLD.

Methods

Six SNPs (rs6499640, rs1421085, rs8050136, rs3751812, rs9939609 and rs9930506) within FTO were genotyped for 741 MAFLD patients (median age, 69.98; interquartile range, 66.55–75.93) and 825 healthy people (median age, 69.94; interquartile range, 66.39–75.64). Allele and genotype frequencies, pairwise linkage disequilibrium (LD) and haplotype analysis were calculated.

Results

BMI, waist circumference, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, triglyceride, alanine transaminase, glutamyl transpeptidase and the prevalence of diabetes were found to be higher in the MAFLD individuals comparing to the control ones (P < 0.05). For rs1421085, the C allele frequency was remarkably higher in MAFLD after Bonferroni correction (OR [95% CI] =1.353 [1.095–1.671]; P_corr =0.030), and a significantly different genotype result was observed in log-additive model (OR [95% CI] =1.369 [1.108–1.691]; P_corr =0.024). For rs8050136, significantly increased A allele frequency was observed in MAFLD (OR [95% CI] =1.371 [1.109–1.695]; P_corr =0.024), and A-allele carriers showed increased MAFLD risk (OR [95% CI] =1.393 [1.103–1.759]; P_corr =0.030). For rs3751812, the T allele frequency was remarkably higher in MAFLD (OR [95% CI] =1.369 [1.108–1.691]; P_corr =0.024), and T-allele carriers demonstrated high MAFLD risk (OR [95% CI] =1.392 [1.103–1.756]; P_corr =0.030). For rs9939609, A allele frequency was also remarkably high in MAFLD (OR [95% CI] =1.369 [1.108–1.691]; P_corr =0.024), and A-allele carriers were more susceptible to MAFLD (OR [95% CI] =[1.103–1.756]; P_corr =0.030). A strong LD was found among rs1421085, rs8050136, rs3751812 and rs9939609 (r² >0.8), and individuals with C-A-T-A haplotype had an elevated MAFLD risk (P =0.005).

Conclusion

The case-control study indicated that C variant of rs1421085, A variant of rs8050136, T variant of rs3751812 and A variant of rs9939609 are associated with elevated MAFLD risk in the older Chinese Han population.

Differences in brain structure and function in children with the FTO obesity-risk allele

OBJECTIVE

Noncoding alleles of the fat mass and obesity-associated (FTO) gene have been associated with obesity risk, yet the underlying mechanisms remain unknown. Risk allele carriers show alterations in brain structure and function, but previous studies have not disassociated the effects of genotype from those of body mass index (BMI).

METHODS

Differences in brain structure and function were examined in children without obesity grouped by their number of copies (0,1,2) of the FTO obesity-risk single-nucleotide polymorphism (SNP) rs1421085. One hundred five 5- to 10-year-olds (5th-95th percentile body fat) were eligible to participate. Usable scans were obtained from 93 participants (15 CC [homozygous risk], 31 CT [heterozygous] and 47 TT [homozygous low risk]).

RESULTS

Homozygous C allele carriers (CCs) showed greater grey matter volume in the cerebellum and temporal fusiform gyrus. CCs also demonstrated increased bilateral cerebellar white matter fibre density and increased resting-state functional connectivity between the bilateral cerebellum and regions in the frontotemporal cortices.

CONCLUSIONS

This is the first study to examine brain structure and function related to FTO alleles in young children not yet manifesting obesity. This study lends support to the notion that the cerebellum may be involved in FTO-related risk for obesity, yet replication and further longitudinal study are required.

Call to action regarding the vascular-bipolar link: A report from the Vascular Task Force of the International Society for Bipolar Disorders

OBJECTIVES

The association of bipolar disorder with early and excessive cardiovascular disease was identified over a century ago. Nonetheless, the vascular-bipolar link remains underrecognized, particularly with regard to how this link can contribute to our understanding of pathogenesis and treatment.

METHODS

An international group of experts completed a selective review of the literature, distilling core themes, identifying limitations and gaps in the literature, and highlighting future directions to bridge these gaps.

RESULTS

The association between bipolar disorder and vascular disease is large in magnitude, consistent across studies, and independent of confounding variables where assessed. The vascular-bipolar link is multifactorial and is difficult to study given the latency between the onset of bipolar disorder, often in adolescence or early adulthood, and subsequent vascular disease, which usually occurs decades later. As a result, studies have often focused on risk factors for vascular disease or intermediate phenotypes, such as structural and functional vascular imaging measures. There is interest in identifying the most relevant mediators of this relationship, including lifestyle (eg, smoking, diet, exercise), medications, and systemic biological mediators (eg, inflammation). Nonetheless, there is a paucity of treatment studies that deliberately engage these mediators, and thus far no treatment studies have focused on engaging vascular imaging targets.

CONCLUSIONS

Further research focused on the vascular-bipolar link holds promise for gleaning insights regarding the underlying causes of bipolar disorder, identifying novel treatment approaches, and mitigating disparities in cardiovascular outcomes for people with bipolar disorder.

Child neurobiology impacts success in family-based behavioral treatment for children with obesity

Background and Objectives:

Family-based behavioral treatment (FBT) is the recommended treatment for children with common obesity. However, there is a large variability in short- and long-term treatment response and mechanisms for unsuccessful treatment outcomes are not fully understood. In this study, we tested if brain response to visual food cues among children with obesity before treatment predicted weight or behavioral outcomes during a 6-mo. behavioral weight management program and/or long-term relative weight maintenance over a 1-year follow-up period.

Subjects and Methods:

Thirty-seven children with obesity (age 9–11y, 62% male) who entered active FBT (attended 2 or more sessions) and had outcome data. Brain activation was assessed at pre-treatment by functional magnetic resonance imaging across an a priori set of appetite-processing brain regions that included the ventral and dorsal striatum, medial orbitofrontal cortex, amygdala, substantia nigra/ventral tegmental area and insula in response to viewing food images before and after a standardized meal.

Results:

Children with more robust reductions in brain activation to high-calorie food cue images following a meal had greater declines in BMI z-score during FBT (r= 0.42; 95% CI: 0.09, 0.66; P=0.02) and greater improvements in Healthy Eating Index scores (r= −0.41; 95% CI: −0.67, −0.06; P=0.02). In whole-brain analyses, greater activation in the ventromedial prefrontal cortex, specifically by high-calorie food cues, was predictive of better treatment outcomes (whole-brain cluster corrected P=0.02). There were no significant predictors of relative weight maintenance and initial behavioral or hormonal measures did not predict FBT outcomes.

Conclusions:

Children’s brain responses to a meal prior to obesity treatment were related to treatment-based weight outcomes, suggesting that neurophysiologic factors and appetitive drive, more so than initial hormone status or behavioral characteristics, limit intervention success.

Contribution of macronutrients to obesity: implications for precision nutrition

The specific metabolic contribution of consuming different energy-yielding macronutrients (namely, carbohydrates, protein and lipids) to obesity is a matter of active debate. In this Review, we summarize the current research concerning associations between the intake of different macronutrients and weight gain and adiposity. We discuss insights into possible differential mechanistic pathways where macronutrients might act on either appetite or adipogenesis to cause weight gain. We also explore the role of dietary macronutrient distribution on thermogenesis or energy expenditure for weight loss and maintenance. On the basis of the data discussed, we describe a novel way to manage excessive body weight; namely, prescribing personalized diets with different macronutrient compositions according to the individual's genotype and/or enterotype. In this context, the interplay of macronutrient consumption with obesity incidence involves mechanisms that affect appetite, thermogenesis and metabolism, and the outcomes of these mechanisms are altered by an individual's genotype and microbiota. Indeed, the interactions of the genetic make-up and/or microbiota features of a person with specific macronutrient intakes or dietary pattern consumption help to explain individualized responses to macronutrients and food patterns, which might represent key factors for comprehensive precision nutrition recommendations and personalized obesity management.

Childhood obesity and the associated rise in cardiometabolic complications

Childhood obesity is one of the most serious global public-health challenges of the twenty-first century. Over the past four decades, the number of children and adolescents with obesity has risen more than tenfold. Worldwide, an increasing number of youth are facing greater exposure to obesity throughout their lives, and this increase will contribute to the early development of type 2 diabetes, fatty liver and cardiovascular complications. Herein, we provide a brief overview of trends in the global shifts in, and environmental and genetic determinants of, childhood obesity. We then discuss recent progress in the elucidation of the central role of insulin resistance, the key element linking obesity and cardiovascular-risk-factor clustering, and the potential mechanisms through which ectopic lipid accumulation leads to insulin resistance and its associated cardiometabolic complications in obese adolescents. In the absence of effective prevention and intervention programs, childhood obesity will have severe public-health consequences for decades to come.

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.

Similarities in Metabolic Flexibility and Hunger Hormone Ghrelin Exist between FTO Gene Variants in Response to an Acute Dietary Challenge

The rs9939609 polymorphism of the fat mass and obesity-associated (FTO) gene has been associated with obesity, and studies have also shown that environmental/lifestyle interaction such as dietary intake might mediate this effect. The current study investigates the postprandial hormonal regulators of hunger and indirect markers of substrate utilisation and metabolic flexibility following a dietary challenge to determine if suppression of circulating ghrelin levels and/or reduced metabolic flexibility exist between FTO genotypes. One hundred and forty seven healthy, sedentary males and females (29.0 ± 0.7 yrs; 70.2 ± 1.1 kg; 169.1 ± 0.8 cm; 24.5 ± 0.3 kg/m²) complete a single experimental session. Anthropometric measures, circulating levels of active ghrelin, insulin and glucose, and substrate oxidation via indirect calorimetry, are measured pre-prandial and/or post-prandial. The FTO rs9939609 variant is genotyped using a real-time polymerase chain reaction. Metabolic flexibility (∆RER) is similar between FTO genotypes of the rs9939609 (T > A) polymorphism (p > 0.05). No differences in pre-prandial and/or postprandial substrate oxidation, plasma glucose, serum insulin or ghrelin are observed between genotypes (p > 0.05). These observations are independent of body mass index and gender. Altered postprandial responses in hunger hormones and metabolic flexibility may not be a mechanism by which FTO is associated with higher BMI and obesity in healthy, normal-weighted individuals.

The FTO genetic variants are associated with dietary intake and body mass index amongst Emirati population

BACKGROUND

The risk of obesity is determined by complex interactions between genetic and environmental factors. Little research to date has investigated the interaction between gene and food intake. The aim of the current study is to explore the potential effect of fat mass and obesity-associated protein gene (FTO) rs9939609 and rs9930506 single nucleotide polymorphism (SNP) on the pattern of food intake in the Emirati population.

METHODS

Adult healthy Emirati subjects with Body mass index (BMI) of 16-40 kg/m2 were included in the study. Genotyping for FTO rs9939609(A>T) and rs9930506(A>G) was performed using DNA from saliva samples. Subjects were categorized according to the WHO classification by calculating the BMI to compare different classes. Dietary intake was assessed by a sixty-one-item FFQ that estimated food and beverage intakes over the past year. The daily energy, macronutrient, and micronutrient consumption were computed.

RESULTS

We included 169 subjects in the final analysis (mean age 30.49± 9.1years, 57.4% females). The mean BMI of the study population was 26.19 kg/m2. Both SNPs were in Hardy Weinberg Equilibrium. The rs9939609 AA genotype was significantly associated with higher BMI (p = 0.004); the effect was significant in females (p = 0.028), but not in males (p = 0.184). Carbohydrate intake was significantly higher in AA subjects with a trend of lower fat intake compared to other genotypes. The odds ratio for the AA was 3.78 in the fourth quartile and 2.67 for the A/T in the second quartile of total carbohydrate intake, considering the first quartile as a reference (95% CI = 1.017-14.1 and 1.03-6.88, respectively). Fat intake was significantly lower in the FTO rs9930506 GG subjects. The presence of FTO rs9930506 GG genotype decreased the fat intake in subjects with FTO rs9939609 AA (p = 0.037).

CONCLUSIONS

The results of this study highlight the interaction of the FTO risk alleles on the food intake in Emirati subjects. The FTO rs9939609 AA subjects had higher carbohydrate and lower fat intake. The latter was accentuated in presence of rs9930506 GG genotype.