The plausibility of sugar addiction and its role in obesity and eating disorders

Disentangling the role of NAc D1 and D2 cells in hedonic eating

Overeating is driven by both the hedonic component ('liking') of food, and the motivation ('wanting') to eat it. The nucleus accumbens (NAc) is a key brain center implicated in these processes, but how distinct NAc cell populations encode 'liking' and 'wanting' to shape overconsumption remains unclear. Here, we probed the roles of NAc D1 and D2 cells in these processes using cell-specific recording and optogenetic manipulation in diverse behavioral paradigms that disentangle reward traits of 'liking' and 'wanting' related to food choice and overeating in healthy mice. Medial NAc shell D2 cells encoded experience-dependent development of 'liking', while D1 cells encoded innate 'liking' during the first food taste. Optogenetic control confirmed causal links of D1 and D2 cells to these aspects of 'liking'. In relation to 'wanting', D1 and D2 cells encoded and promoted distinct aspects of food approach: D1 cells interpreted food cues while D2 cells also sustained food-visit-length that facilitates consumption. Finally, at the level of food choice, D1, but not D2, cell activity was sufficient to switch food preference, programming subsequent long-lasting overconsumption. By revealing complementary roles of D1 and D2 cells in consumption, these findings assign neural bases to 'liking' and 'wanting' in a unifying framework of D1 and D2 cell activity.

A High-Sugar Diet Consumption, Metabolism and Health Impacts with a Focus on the Development of Substance Use Disorder: A Narrative Review

Carbohydrates are important macronutrients in human and rodent diet patterns that play a key role in crucial metabolic pathways and provide the necessary energy for proper body functioning. Sugar homeostasis and intake require complex hormonal and nervous control to proper body energy balance. Added sugar in processed food results in metabolic, cardiovascular, and nervous disorders. Epidemiological reports have shown enhanced consumption of sweet products in children and adults, especially in reproductive age and in pregnant women, which can lead to the susceptibility of offspring’s health to diseases in early life or in adulthood and proneness to mental disorders. In this review, we discuss the impacts of high-sugar diet (HSD) or sugar intake during the perinatal and/or postnatal periods on neural and behavioural disturbances as well as on the development of substance use disorder (SUD). Since several emotional behavioural disturbances are recognized as predictors of SUD, we also present how HSD enhances impulsive behaviour, stress, anxiety and depression. Apart from the influence of HSD on these mood disturbances, added sugar can render food addiction. Both food and addictive substances change the sensitivity of the brain rewarding neurotransmission signalling. The results of the collected studies could be important in assessing sugar intake, especially via maternal dietary patterns, from the clinical perspective of SUD prevention or pre-existing emotional disorders. Methodology: This narrative review focuses on the roles of a high-sugar diet (HSD) and added sugar in foods and on the impacts of glucose and fructose on the development of substance use disorder (SUD) and on the behavioural predictors of drugs abuse. The literature was reviewed by two authors independently according to the topic of the review. We searched the PubMed and Scopus databases and Multidisciplinary Digital Publishing Institute open access scientific journals using the following keyword search strategy depending on the theme of the chapter: “high-sugar diet” OR “high-carbohydrate diet” OR “sugar” OR “glucose” OR “fructose” OR “added sugar” AND keywords. We excluded inaccessible or pay-walled articles, abstracts, conference papers, editorials, letters, commentary, and short notes. Reviews, experimental studies, and epidemiological data, published since 1990s, were searched and collected depending on the chapter structure. After the search, all duplicates are thrown out and full texts were read, and findings were rescreened. After the selection process, appropriate papers were included to present in this review.

Action-Shapers and Their Neuro-Immunological Foundations

Not all our intentions translate into actions, as our capacity to act may be influenced by a variety of mental and biochemical factors. In this article, we present a comprehensive account of how neuro-immunological processes affect our intentional abilities and our capacity to act. We do so by extending the theory of thought-shapers (TTS) through the notion of action-shapers and combining this theory with the essential embodiment thesis (EE). This thesis about the mind-body relation says that human minds are necessarily and completely embodied. Action-shapers dynamically constitute the action-space of individuals, affecting their capacity to take action or to select one course of action over another. We highlight the effects and interactions of neuro-immunological effective processes in the body to demonstrate how they shape the action-space. In this article, we consider neuro-immunological effective processes that influence the gut-brain axis, chronic stress, high levels of sugar intake, the amygdala and the effects of prolonged stress. We investigate the effects of these processes on the perception and on the capacity to form intentions and act on them. We conclude the paper by providing a concise account of action-shapers, in which we attempt to summarize the line of argumentation and provide suggestions for further research.

What are the benefits and risks of nutrition policy actions to reduce added sugar consumption? An Australian case study

OBJECTIVE

This study aimed to critically analyse Australia's current and proposed policy actions to reduce added sugar consumption. Over-consumption of added sugar is a significant public health nutrition issue. The competing interests, values and beliefs among stakeholders mean they have disparate views regarding which policy actions are preferable to reduce added sugar consumption.

DESIGN

Semi-structured interviews using purposive, snowball sampling and policy mapping. Policy actions were classified by two frameworks: NOURISHING (e.g. behaviour change communication, food environment and food system) and the Orders of Change (e.g. first order: technical adjustments, second order: reforming the system, third order: transforming the system).

SETTING

Australia.

PARTICIPANTS

Twenty-two stakeholders from the food industry, food regulation, government, public health groups and academia.

RESULTS

All proposed and existing policy actions targeted the food environment/behaviour change; most were assessed as first-order changes, and reductionist (nutrient specific) in nature. Influences on policy actions included industry power, stakeholder fragmentation, government ideology/political will and public pressure. Few stakeholders considered potential risks of policy actions, particularly of non-nutritive sweetener substitution or opportunity costs for other policies.

CONCLUSIONS

Most of Australia's policy actions to reduce added sugar consumption are reductionist. Preferencing nutrient specific, first-order policy actions could reflect the influence of vested interests, a historically dominant reductionist orientation to nutrition science and policy, and the perceived difficulty of pursuing second- or third-order changes. Pursuing only first-order policy actions could lead to 'regrettable' substitutions and creates an opportunity cost for more comprehensive policy aimed at adjusting the broader food system.

Impaired leptin responsiveness in the nucleus accumbens of leptin-overexpressing transgenic mice with dysregulated sucrose and lipid preference independent of obesity

While hypothalamic leptin resistance can occur prior to establishment of obesity, clarification is needed as to whether the impaired response to leptin in the reward-related nuclei occurs independently of obesity. To answer this question, we attempted to dissociate the normally coexisting leptin resistance from obesity. We investigated phenotypes of leptin-overexpressing transgenic mice fed for 1 week with 60 % high-fat diet (HFD) (LepTg-HFD1W mice). After 1 week, we observed that LepTg-HFD1W mice weighed as same as wild type (WT) mice fed standard chow diet (CD) for 1 week (WT-CD1W mice). However, compared to WT-CD1W mice, LepTg-HFD1W mice exhibited attenuated leptin-induced anorexia, decreased leptin-induced c-fos immunostaining in nucleus accumbens (NAc), one of important site of reward system, decreased leptin-stimulated pSTAT3 immunostaining in hypothalamus. Furthermore, neither sucrose nor lipid preference was suppressed by leptin in LepTg-HFD1W mice. On the contrary, leptin significantly suppressed both preferences in WT mice fed HFD (WT-HFD1 W mice). These results indicate that leptin responsiveness decreases in NAc independently of obesity. Additionally, in this situation, suppressive effect of leptin on the hedonic feeding results in impaired regulation. Such findings suggest the impaired leptin responsiveness in NAc partially contributes to dysregulated hedonic feeding behavior independently of obesity.

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

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

Food addiction symptoms are related to neuroaffective responses to preferred binge food and erotic cues

It has been proposed that some individuals succumb to maladaptive eating behaviors because, like those with addiction, they attribute high incentive salience to food-associated cues. Here, we tested whether women that attribute high incentive salience to food-associated cues report high food addiction symptomatology. In 76 college women, we assessed self-reported food addiction symptoms using the Yale Food Addiction Scale and we recorded event-related potentials (ERPs, a direct measure of brain activity) to preferred food, erotic, unpleasant, and neutral images. We used the amplitude of the late positive potential (LPP, a component of the ERPs) as an index of the incentive salience attributed to the images. Using a multivariate classification algorithm (k-means cluster analysis), we identified two neuroaffective reactivity profiles that have been previously associated with individual differences in the tendency to attribute incentive salience to cues and with differences in vulnerability to addictive behaviors. Results showed that women with elevated LPP responses to preferred food cues relative to erotic images report higher food addiction symptoms than women with low LPP responses to preferred food cues relative to other motivationally relevant stimuli. These results support the hypothesis that individual differences in the tendency to attribute incentive salience to food cues play an important role in modulating food addiction symptomatology.

Does the Australian Health Star Rating System Encourage Added Sugar Reformulation? Trends in Sweetener Use in Australia

Dietary risk factors, including excess added sugar intake, are leading contributors to Australia's burden of disease. An objective of the Australian Health Star Rating (HSR) system is to encourage the reformulation of packaged foods. Manufacturers may improve a product's HSR by replacing added sugar with non-nutritive sweeteners (NNS). Concerns have been raised regarding the potential substitution effects of ultra-processed foods containing NNS for whole foods, and the long-term impact this may have on population health. The aim of this study was to determine whether the implementation of the HSR system has impacted the use of added sugars and NNS in the food supply. Four product categories were used: products with no added sweetener, products containing added sugar only, products containing NNS only, and products containing a combination of added sugar and NNS. Of 6477 newly released products analyzed displaying a HSR in Australia between 2014-2020, 63% contained added sugars. The proportion of new products sweetened with added sugars increased over time, while NNS use did not, despite a higher average and median HSR for products sweetened with NNS. These findings suggest that at the current time, the HSR system may not discourage the use of added sugars in new products or incentivize the reformulation of added sugar with NNS. As the health risks of NNS are questioned, increased reformulation of products with NNS to reduce the presence of added sugar in the food supply may not address broader health concerns. Instead, supporting the promotion of whole foods and drinks should be prioritized, as well as policy actions that reduce the proliferation and availability of UPFs.

Ultraprocessed Food: Addictive, Toxic, and Ready for Regulation

Past public health crises (e.g., tobacco, alcohol, opioids, cholera, human immunodeficiency virus (HIV), lead, pollution, venereal disease, even coronavirus (COVID-19) have been met with interventions targeted both at the individual and all of society. While the healthcare community is very aware that the global pandemic of non-communicable diseases (NCDs) has its origins in our Western ultraprocessed food diet, society has been slow to initiate any interventions other than public education, which has been ineffective, in part due to food industry interference. This article provides the rationale for such public health interventions, by compiling the evidence that added sugar, and by proxy the ultraprocessed food category, meets the four criteria set by the public health community as necessary and sufficient for regulation—abuse, toxicity, ubiquity, and externalities (How does your consumption affect me?). To their credit, some countries have recently heeded this science and have instituted sugar taxation policies to help ameliorate NCDs within their borders. This article also supplies scientific counters to food industry talking points, and sample intervention strategies, in order to guide both scientists and policy makers in instituting further appropriate public health measures to quell this pandemic.

Prefrontal brain stimulation during food-related inhibition training: effects on food craving, food consumption and inhibitory control

Modulation of dorsolateral prefrontal cortex (DLPFC) activity using non-invasive brain stimulation has been shown to reduce food craving as well as food consumption. Using a preregistered design, we examined whether bilateral transcranial direct current stimulation (tDCS) of the DLPFC could reduce food craving and consumption in healthy participants when administered alongside the cognitive target of inhibitory control training. Participants (N = 172) received either active or sham tDCS (2 mA; anode F4, cathode F3) while completing a food-related Go/No-Go task. State food craving, ad-lib food consumption and response inhibition were evaluated. Compared with sham stimulation, we found no evidence for an effect of active tDCS on any of these outcome measures in a predominantly female sample. Our findings raise doubts about the effectiveness of single-session tDCS on food craving and consumption. Consideration of individual differences, improvements in tDCS protocols and multi-session testing are discussed.

Children's propensity to consume sugar and fat predicts regular alcohol consumption in adolescence

Objective

The present study investigated the association between sugar and fat intake in childhood in relation to alcohol use in adolescence. We hypothesized that early exposure to diets high in fat and sugar may affect ingestive behaviours later in life, including alcohol use.

Design/Setting/Subjects

Children from the European IDEFICS/I.Family cohort study were examined at ages 5–9 years and followed up at ages 11–16 years. FFQ were completed by parents on behalf of children, and later by adolescents themselves. Complete data were available in 2263 participants. Children’s propensities to consume foods high in fat and sugar were calculated and dichotomized at median values. Adolescents’ use of alcohol was classified as at least weekly v. less frequent use. Log-binomial regression linked sugar and fat consumption in childhood to risk of alcohol use in adolescence, adjusted for relevant covariates.

Results

Five per cent of adolescents reported weekly alcohol consumption. Children with high propensity to consume sugar and fat were at greater risk of later alcohol use, compared with children with low fat and low sugar propensity (relative risk=2·46; 95 % CI 1·47, 4·12), independent of age, sex and survey country. The association was not explained by parental income and education, strict parenting style or child's health-related quality of life and was only partly mediated by sustained consumption of sugar and fat into adolescence.

Conclusions

Frequent consumption of foods high in fat and sugar in childhood predicted regular use of alcohol in adolescence.

Food addiction: is it a nosological category or a psychopathological dimension? Preliminary results of an Italian study

Background

Food addiction (FA) is a controversial concept, denoting the craving for certain foods. Given the little information available, the aim of this study was to evaluate the possible relationships between FA and full-blown and subthreshold psychopathology or eating behaviors in subjects consulting nutritional biologists.

Materials and methods

Three-hundred and fifty subjects completed the following self-questionnaires: Yale Food Addiction Scale (YFAS), Structured Clinical Interview for Mood Spectrum, Self-Report, Lifetime Version (MOOD-SR-LT), Symptom Checklist-90-Revised (SCL-90-R), Structured Clinical Interview for Anorexic-Bulimic Spectrum, Self-Report, Lifetime Version (ABS-SR-LT).

Results

Most of the subjects were women (n = 278) and the remaining were 72 men. A large proportion of the subjects (77.1%) had a YFAS score <3 and 22.9% ≥3, with no difference between men and women. The YFAS scores ≥3 were significantly and positively related to the all ABS-SR-LT domains, as well as to three dimensions (Depression, Hypomania, Rhythmicity) of the MOOD-SR-LT, and some SCL-90-R domains (Sensitivity, Psychoticism, General Symptom Index and Positive Symptom).

Conclusion

Our data, while indicating that FA is related to different subthreshold psychopathological domains, in particular, with both depressive and manic symptoms, as well as with rhythmicity of mood spectrum, or with eating subthreshold symptoms, would suggest that it might be a dimension underlying different conditions or symptom clusters.

A narrative review of potential treatment strategies for food addiction

The concept of food addiction (FA) remains controversial with research being in the nascent stages; FA like any addiction can have a devastating impact on the lives of those afflicted. There exists a clinical need for treatment strategies for those affected. This article reviews potential treatment strategies for FA. The treatment strategies target four core behaviours of the addiction phenotype specifically craving through the opioid system, impulsivity as a personality trait, compulsivity through the serotonergic system and lastly motivation through the dopaminergic system. A range of pharmacological and psychological interventions are reviewed. Future research should seek to test and validate the proposed clinical treatment strategies.

A Potential Animal Model of Maladaptive Palatable Food Consumption Followed by Delayed Discomfort

Introduction: Binging is the consumption of larger amounts of food in a briefer period of time than would normally be consumed under similar circumstances. Binging requires palatable food (PF) to trigger abnormal eating, probably reflecting gene × environment interactions. In this study we examined the impact of trait binge eating (BE) and its compulsive nature on the conflict between hedonic eating of PF and anticipation of a delayed aversive effect. We used female rats as an animal model similar to other models of BE. A novel aspect of this model in this paper is the use of a delayed internal aversive effect produced by lactose ingestion. Establishing this model will allow us to better understand the nature of the conflict between immediate reward and its delayed aversive implications. We hypothesized that BE prone (BEP) rats will demonstrate maladaptive decision making, presenting higher motivation toward PF even when this is associated with delayed discomfort. Method: (Phase 1) 52 female adult Wistar rats were divided to two eating profiles: resistant and prone binge eaters (BER/BEP) based on intake of liquid PF (Ensure). Next, all subjects underwent a Lactose Conditioning Protocol (LCP) that included 4 h tests, one baseline and 3 conditioning days (Phase 2), in which solid PF (Oreo cookies) was paired with glucose (control-no internal aversive effect) or lactose, dissolved in liquid PF. Index for PF motivation was PF consumption during the 4 h LCP. To test for memory of lactose conditioning, we performed another LCP with glucose only (anticipation, but no actual lactose-induced discomfort), a week after the last conditioning session. Results: Lactose conditioned BEP showed higher motivation toward PF compared to lactose conditioned BER faced with delayed aversive effects. Only lactose conditioned BER rats devaluated the PF over LCP days, indicating an association between PF and abdominal discomfort. In addition, only lactose conditioned BER presented an adaptive dynamic behavior, by varying PF intake according to consequences. Furthermore, solid PF consumption was predicted by binge size of liquid PF, only for lactose conditioned rats. Conclusions: We established an animal model for a common eating conflict in humans using delayed internal aversive unconditional stimuli.

Food addiction as a proxy for eating disorder and obesity severity, trauma history, PTSD symptoms, and comorbidity

PURPOSE

Food addiction (FA) is a newly defined yet still controversial condition that has important etiological, developmental, treatment, prevention, and social policy implications. In this review, the case is made that FA (or high scores on the Yale Food Addiction Scale) may be used as a proxy measure for a matrix of interrelated clinical features, including greater eating disorder severity, greater obesity severity, more severe trauma histories, greater symptoms of posttraumatic stress disorder (PTSD), greater psychiatric comorbidity, as well as greater medical morbidity and mortality.

METHODS

A Medline search was undertaken using the following terms: food addiction cross-referenced with eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder, and binge eating), obesity, trauma, posttraumatic stress disorder, and comorbidity.

RESULTS

The thesis is that the identification and acknowledgment of the concept of FA, when integrated into an overall, trauma-focused and transdiagnostic treatment approach, are supported and can be useful in understanding clinically the "big picture."

CONCLUSIONS

Food addiction (FA) may be used as a proxy for (1) bulimic eating disorder severity, (2) complex trauma histories, (3) severity of PTSD and PTSD symptoms, (4) intensity of psychiatric comorbidity, (5) severity of obesity, as well as (6) their combination. Implications for developing treatment strategies are discussed. The case for a comprehensive management that requires careful attention to medical and psychiatric assessment and integrated care that incorporates trauma-focused treatment is made.

Neuroclinical Framework for the Role of Stress in Addiction

Addiction has been conceptualized as a three-stage cycle—binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation—that worsens over time and involves allostatic changes in hedonic function via changes in the brain reward and stress systems. Using the withdrawal/negative affect stage and negative reinforcement as an important source of motivation for compulsive drug seeking, we outline the neurobiology of the stress component of the withdrawal/negative affect stage and relate it to a derivative of the Research Domain Criteria research construct for the study of psychiatric disease, known as the Addictions Neuroclinical Assessment. Using the Addictions Neuroclinical Assessment, we outline five subdomains of negative emotional states that can be operationally measured in human laboratory settings and paralleled by animal models. We hypothesize that a focus on negative emotionality and stress is closely related to the acute neurobiological alterations that are experienced in addiction and may serve as a bridge to a reformulation of the addiction nosology to better capture individual differences in patients for whom the withdrawal/negative affect stage drives compulsive drug taking.

Eating dependence and weight gain; no human evidence for a 'sugar-addiction' model of overweight

BACKGROUND AND AIMS

There is an increasing societal concern that consumption of specific foods such as sugar might become 'addictive' and, hence, promote weight gain. Claims about the addictiveness of sugar however are based largely on findings from few animal studies, whereas there is a lack of direct human evidence for symptoms of sugar-related substance dependence. The current study examined in a large sample of human participants whether foods mainly containing sugar in particular might cause 'addiction-like' problems that meet clinical DSM criteria for substance dependence, and, also whether in turn this relates to body weight and negative affectivity (depressed mood).

METHODS

In a cross-sectional study, n = 1495 university students from a variety of faculties were assessed for DSM-related signs of food addiction for particular food categories (YFAS), and, also BMI and negative affectivity.

RESULTS

Results revealed that from the total sample, 95% experienced at least one symptom of food dependence and 12.6% met the YFAS classification for 'food addiction' as related to DSM-IV criteria. The majority of respondents experienced these problems for combined high-fat savoury (30%) and high-fat sweet (25%) foods, whereas only a minority experienced such problems for low-fat/savoury (2%) and mainly sugar-containing foods (5%). Overweight correlated only with addictive-like problems for high-fat savoury and high-fat sweet foods (P < 0.0001), while this was not found for foods mainly containing sugar.

CONCLUSION

The current findings indicate that sugary foods contribute minimally to 'food dependence' and increased risk of weight gain. Instead, they are consistent with the current scientific notion that food energy density, and the unique individual experience of eating, plays an important role in determining the reward value of food and promoting excessive energy intake.

A Rat Drinking in the Dark Model for Studying Ethanol and Sucrose Consumption

Background: The intermittent access 2-bottle choice (IA2BC) and drinking in the dark (DID) models were developed for studying rodent binge-like consumption. Traditionally, IA2BC was used with rats and DID with mice. Recently, IA2BC was adapted to study mouse ethanol consumption. However, it is unknown whether DID is suitable for rats or if one rat model is more advantageous than another for studying binge-like consumption.

Methods: Male Wistar rats consumed 20% ethanol or 5% sucrose using IA2BC or DID for 12 weeks. IA2BC drinking sessions occurred on alternate days (Mondays–Fridays) and lasted 24 h, whereas DID sessions ran 4 h/day, 5 days/week (Monday–Friday). Average consumption/session, week and hour was measured. To explore DID model suitability for screening novel compounds for controlling ethanol and sucrose intake, varenicline (2 mg/kg) or vehicle was administered to DID rats.

Results: IA2BC rats consume more ethanol/session and similar amounts of ethanol/week than DID rats. While, IA2BC rats consume more sucrose/session and week than DID rats. Although IA2BC rats had more ethanol and sucrose access time, DID rats had greater ethanol and sucrose intake/hour. Varenicline significantly reduced ethanol and sucrose consumption in DID rats, consistent with previously published IA2BC studies.

Conclusions: Despite the shorter access time, the rat DID model induced higher initial intake and greater consumption/hour for both ethanol and sucrose. The shorter duration of DID sessions did not prevent detection of varenicline-induced reductions in ethanol or sucrose consumption, suggesting the DID model may be suitable for studying binge-like ethanol and sucrose consumption.

Attentional and motor impulsivity interactively predict 'food addiction' in obese individuals

BACKGROUND

Impulsivity is a multifaceted construct and constitutes a common risk factor for a range of behaviors associated with poor self-control (e.g., substance use or binge eating). The short form of the Barratt Impulsiveness Scale (BIS-15) measures impulsive behaviors related to attentional (inability to focus attention or concentrate), motor (acting without thinking), and non-planning (lack of future orientation or forethought) impulsivity. Eating-related measures appear to be particularly related to attentional and motor impulsivity and recent findings suggest that interactive effects between these two facets may play a role in eating- and weight-regulation.

METHODS

One-hundred thirty-three obese individuals presenting for bariatric surgery (77.4% female) completed the BIS-15 and the Yale Food Addiction Scale (YFAS) 2.0, which measures addiction-like eating based on the eleven symptoms of substance use disorder outlined in the fifth version of the Diagnostic and Statistical Manual of Mental Disorders.

RESULTS

Sixty-three participants (47.4%) were classified as being 'food addicted'. Scores on attentional and motor impulsivity interactively predicted 'food addiction' status: higher attentional impulsivity was associated with a higher likelihood of receiving a YFAS 2.0 diagnosis only at high (+1 SD), but not at low (-1 SD) levels of motor impulsivity.

CONCLUSIONS

Results support previous findings showing that non-planning impulsivity does not appear to play a role in eating-related self-regulation. Furthermore, this is the first study that shows interactive effects between different impulsivity facets when predicting 'food addiction' in obese individuals. Self-regulatory failure in eating-regulation (e.g., addiction-like overeating) may particularly emerge when both attentional and motor impulsivity levels are elevated.

A meta-analysis of the relationship between brain dopamine receptors and obesity: a matter of changes in behavior rather than food addiction?

Addiction to a wide range of substances of abuse has been suggested to reflect a ‘Reward Deficiency Syndrome'. That is, drugs are said to stimulate the reward mechanisms so intensely that, to compensate, the population of dopamine D₂ receptors (DD2R) declines. The result is that an increased intake is necessary to experience the same degree of reward. Without an additional intake, cravings and withdrawal symptoms result. A suggestion is that food addiction, in a similar manner to drugs of abuse, decrease DD2R. The role of DD2R in obesity was therefore examined by examining the association between body mass index (BMI) and the Taq1A polymorphism, as the A1 allele is associated with a 30–40% lower number of DD2R, and is a risk factor for drug addiction. If a lower density of DD2R is indicative of physical addiction, it was argued that if food addiction occurs, those with the A1 allele should have a higher BMI. A systematic review found 33 studies that compared the BMI of those who did and did not have the A1 allele. A meta-analysis of the studies compared those with (A1/A1 and A1/A2) or without (A2/A2) the A1 allele; no difference in BMI was found (standardized mean difference 0.004 (s.e. 0.021), variance 0.000, Z=0.196, P<0.845). It was concluded that there was no support for a reward deficiency theory of food addiction. In contrast, there are several reports that those with the A1 allele are less able to benefit from an intervention that aimed to reduce weight, possibly a reflection of increased impulsivity.

Relationship between Added Sugars Consumption and Chronic Disease Risk Factors: Current Understanding

Added sugars are a controversial and hotly debated topic. Consumption of added sugars has been implicated in increased risk of a variety of chronic diseases including obesity, cardiovascular disease, diabetes and non-alcoholic fatty liver disease (NAFLD) as well as cognitive decline and even some cancers. Support for these putative associations has been challenged, however, on a variety of fronts. The purpose of the current review is to summarize high impact evidence including systematic reviews, meta-analyses, and randomized controlled trials (RCTs), in an attempt to provide an overview of current evidence related to added sugars and health considerations. This paper is an extension of a symposium held at the Experimental Biology 2015 conference entitled “Sweeteners and Health: Current Understandings, Controversies, Recent Research Findings and Directions for Future Research”. We conclude based on high quality evidence from randomized controlled trials (RCT), systematic reviews and meta-analyses of cohort studies that singling out added sugars as unique culprits for metabolically based diseases such as obesity, diabetes and cardiovascular disease appears inconsistent with modern, high quality evidence and is very unlikely to yield health benefits. While it is prudent to consume added sugars in moderation, the reduction of these components of the diet without other reductions of caloric sources seems unlikely to achieve any meaningful benefit.

Sugars, obesity, and cardiovascular disease: results from recent randomized control trials

The relationship between sugar consumption and various health-related sequelas is controversial. Some investigators have argued that excessive sugar consumption is associated with increased risk of obesity, coronary heart disease, diabetes (T2D), metabolic syndrome, non-alcoholic fatty liver disease, and stimulation of reward pathways in the brain potentially causing excessive caloric consumption. These concerns have influenced organizations such as the World Health Organization, the Scientific Advisory Committee on Nutrition in England not to exceed 5 % of total energy and the Dietary Guidelines for Americans Advisory Committee 2015 to recommend upper limits of sugar consumption not to exceed 10 % of calories. Data from many randomized control trials (RCTs) do not support linkages between sugar consumption at normal levels within the human diet and various adverse metabolic and health-related effects. Fructose and glucose are typically consumed together in roughly equal proportions from high-fructose corn syrup (also known as isoglucose in Europe) or sucrose. The purpose of this review is to present data from recent RCTs and findings from recent systematic reviews and meta-analyses related to sugar consumption and its putative health effects. This review evaluates findings from recent randomized controlled trials, systematic reviews and meta-analyses into the relationship of sugar consumption and a range of health-related issues including energy-regulating hormones, obesity, cardiovascular disease, diabetes, and accumulation of liver fat and neurologic responses. Data from these sources do not support linkages between sugar consumption at normal levels within the human diet and various adverse metabolic and health-related effects.

Prolonged Consumption of Sucrose in a Binge-Like Manner, Alters the Morphology of Medium Spiny Neurons in the Nucleus Accumbens Shell

The modern diet has become highly sweetened, resulting in unprecedented levels of sugar consumption, particularly among adolescents. While chronic long-term sugar intake is known to contribute to the development of metabolic disorders including obesity and type II diabetes, little is known regarding the direct consequences of long-term, binge-like sugar consumption on the brain. Because sugar can cause the release of dopamine in the nucleus accumbens (NAc) similarly to drugs of abuse, we investigated changes in the morphology of neurons in this brain region following short- (4 weeks) and long-term (12 weeks) binge-like sucrose consumption using an intermittent two-bottle choice paradigm. We used Golgi-Cox staining to impregnate medium spiny neurons (MSNs) from the NAc core and shell of short- and long-term sucrose consuming rats and compared these to age-matched water controls. We show that prolonged binge-like sucrose consumption significantly decreased the total dendritic length of NAc shell MSNs compared to age-matched control rats. We also found that the restructuring of these neurons resulted primarily from reduced distal dendritic complexity. Conversely, we observed increased spine densities at the distal branch orders of NAc shell MSNs from long-term sucrose consuming rats. Combined, these results highlight the neuronal effects of prolonged binge-like intake of sucrose on NAc shell MSN morphology.

The Influence of Palatable Diets in Reward System Activation: A Mini Review

The changes in eating patterns that have occurred in recent decades are an important cause of obesity. Food intake and energy expenditure are controlled by a complex neural system involving the hypothalamic centers and peripheral satiety system (gastrointestinal and pancreatic hormones). Highly palatable and caloric food disrupts appetite regulation; however, palatable foods induce pleasure and reward. The cafeteria diet is such a palatable diet and has been shown consistently to increase body weight and induce hyperplasia in animal obesity models. Moreover, palatable high-fat foods (such as those of the cafeteria diet) can induce addiction-like deficits in brain reward function and are considered to be an important source of motivation that might drive overeating and contribute to the development of obesity. The mechanism of neural adaptation triggered by palatable foods is similar to those that have been reported for nondrug addictions and long-term drug use. Thus, this review attempts to describe the potential mechanisms that might lead to highly palatable diets, such as the cafeteria diet, triggering addiction, or compulsion through the reward system.

Parental control and overconsumption of snack foods in overweight and obese children

The associations between snack food consumption, parent feeding practices and general parenting in overweight in obese children are largely unknown. Therefore, we examined these relationships in 117 treatment-seeking overweight and obese children (10.40 ± 1.35 years; 53% female; 52% Caucasian; BMI-z: 2.06 ± .39). Children consumed a dinner meal, completed an Eating in the Absence of Hunger (EAH) free access paradigm (total EAH intake = EAH%-total; sweet food intake = EAH%-sweet), and completed the Child Report of Parent Behavior Inventory. Parents completed the Child Feeding Questionnaire. Child EAH%-total and EAH%-sweet were positively associated with dinner consumption (p's < .01). Girls had significantly higher EAH%-total compared to boys (p < .05). In separate models, higher EAH%-total was associated with greater use of maternal psychological control (p < .05) and EAH%-sweet was positively associated with parent monitoring (p < .05). In analyses examining factors associated with the consumption of specific foods, EAH snack food, parent restriction, pressure to eat, monitoring, and maternal psychological control were positively correlated with intake of Hershey's(®) chocolate bars (p's < .05). In summary, parental monitoring is associated with child sweet snack food intake and maternal psychological control is associated with child total snack food consumption. Future research should evaluate the complex relationship between child eating and parenting, especially with regard to subgroups of foods.

Sugar addiction: the state of the science

PURPOSE

As obesity rates continue to climb, the notion that overconsumption reflects an underlying 'food addiction' (FA) has become increasingly influential. An increasingly popular theory is that sugar acts as an addictive agent, eliciting neurobiological changes similar to those seen in drug addiction. In this paper, we review the evidence in support of sugar addiction.

METHODS

We reviewed the literature on food and sugar addiction and considered the evidence suggesting the addictiveness of highly processed foods, particularly those with high sugar content. We then examined the addictive potential of sugar by contrasting evidence from the animal and human neuroscience literature on drug and sugar addiction.

RESULTS

We find little evidence to support sugar addiction in humans, and findings from the animal literature suggest that addiction-like behaviours, such as bingeing, occur only in the context of intermittent access to sugar. These behaviours likely arise from intermittent access to sweet tasting or highly palatable foods, not the neurochemical effects of sugar.

CONCLUSION

Given the lack of evidence supporting it, we argue against a premature incorporation of sugar addiction into the scientific literature and public policy recommendations.

A Systematic Review of the Application And Correlates of YFAS-Diagnosed 'Food Addiction' in Humans: Are Eating-Related 'Addictions' a Cause for Concern or Empty Concepts?

The proposition of so-called 'food addiction' (FA) in the scientific literature has stimulated a recent surge in research and debate. The concept of FA is controversial, and opinion is divided. Many of the findings depend upon the use of a single instrument called the Yale Food Addiction Scale (YFAS). This review systematically examined FA, as defined by the YFAS, reported in 40 experimental human studies published in or after 2009. The results indicated that much of the literature makes the supposition that food addiction is an accepted neurobiological disease, consistent with substance use disorders; an interpretation based on very limited data. This raises the question as to whether those individuals who meet the YFAS criteria for diagnosis are truly 'addicted' to food or if they experience significant impairment to their psychological wellbeing and quality of life as would be expected in clinically recognised addictive disorders. At the present time, little research has investigated the extent to which a psychometric self-assessment of FA symptomatology can elucidate a harmful relationship with target foods in the diet. A positive YFAS diagnosis is usually positively associated with BMI and strongly linked with the presence of binge eating, but certain exceptions within the literature were revealed. Further clarification is required as to whether so-called FA is sufficiently different to existing conditions and traits to warrant classification as a distinctive disease phenotype rather than an expression of strong habits and preferences.

Current considerations regarding food addiction

"Food addiction" is an emerging area, and behavioral and biological overlaps have been observed between eating and addictive disorders. Potential misconceptions about applying an addiction framework to problematic eating behavior may inhibit scientific progress. Critiques of "food addiction" that focus on descriptive differences between overeating and illicit drugs are similar to early criticisms of the addictiveness of tobacco. Although food is necessary for survival, the highly processed foods associated with addictive-like eating may provide little health benefit. Individual differences are important in determining who develops an addiction. If certain foods are addictive, the identification of possible risk factors for "food addiction" is an important next step. Not all treatments for addiction require abstinence. Addiction interventions that focus on moderation or controlled use may lead to novel approaches to treating eating-related problems. Finally, addiction-related policies that focus on environmental (instead of educational) targets may have a larger public health impact in reducing overeating.

Food addiction in overweight and obese adolescents seeking weight-loss treatment

Some forms of overeating closely resemble addictive behaviour. The Yale Food Addiction Scale (YFAS) was developed to measure such addiction-like eating in humans and has been employed in numerous studies for examining food addiction in adults. Yet, little is known about food addiction in children and adolescents. Fifty adolescents were recruited at the beginning of treatment in a weight-loss hospital and completed the YFAS among other questionnaires. Nineteen participants (38%) received a YFAS diagnosis, who did not differ in age, body mass and gender distribution from those not receiving a diagnosis. However, those with food addiction reported more binge days, more frequent food cravings, higher eating, weight and shape concerns, more symptoms of depression and higher attentional and motor impulsivity. Eating restraint and nonplanning impulsivity did not differ between groups. Results replicate findings from studies in obese adults such that food addiction is not related to age, gender, body mass or eating restraint, but to higher eating pathology, more symptoms of depression and higher impulsivity. Furthermore, results highlight that particularly attentional impulsivity is related to 'food addiction'. Addiction-like eating appears to be a valid phenotype in a substantial subset of treatment-seeking, obese adolescents.

Intense Sweeteners, Appetite for the Sweet Taste, and Relationship to Weight Management

High intensity, low-energy sweeteners (LES) are used by many consumers in order to limit energy intake and possibly facilitate body weight control. These beneficial effects are often questioned in the scientific and lay media. LES are frequently accused of stimulating and/or maintaining a liking for sweetness which in turn would be deleterious for adequate body weight control. Evidence for the specific effects of LES use on appetite for sweet products will be extracted from observational studies, experimental laboratory studies, randomized controlled trials, and finally brain imaging studies. While many of the existing studies cannot identify any causal links between use of LES and appetite for sweetness, randomized trials in children and adults suggest that use of LES tends to reduce rather than increase the intake of sugar-containing foods and to facilitate, rather than impair, weight loss.

Atitudes de nutricionistas em relação a indivíduos obesos – um estudo exploratório

O objetivo foi identificar atitudes de nutricionistas em relação à obesidade; envolvendo crenças sobre características atribuídas às pessoas obesas, fatores de desenvolvimento e a obesidade em si. Os participantes (N = 344; 97,1% mulheres) foram contatados via conselho profissional e responderam a pesquisa online. As questões do estudo foram adaptadas de trabalhos internacionais com as respostas analisadas por frequência de concordância. As respostas indicaram forte estigmatização da obesidade e preconceito contra o obeso, atribuindo características como: guloso (67,4%), não atraente (52,0%), desajeitado (55,1%), sem determinação (43,6%) e preguiçoso (42,3%). E considerando entre os mais importantes fatores causais: alterações emocionais e de humor, vício ou dependência de comida e baixa autoestima. Esta temática deve ser mais pesquisada uma vez que tais atitudes podem impactar a eficácia do tratamento; também para discussão e formação ampla sobre os significados da obesidade, e tratamento mais individualizado e humanizado para pacientes obesos.

Evidence for a compulsive-like behavior in rats exposed to alternate access to highly preferred palatable food

Converging evidence suggests that recurrent excessive calorie restriction causes binge eating by promoting behavioral disinhibition and overeating. This interpretation suggests that cognitive adaptations may surpass physiological regulations of metabolic needs after recurrent cycles of dieting and binging. Intermittent access to palatable food has long been studied in rats, but the consequences of such diet cycling procedures on the cognitive control of food seeking remain unclear. Female Wistar rats were divided in two groups matched for food intake and body weight. One group received standard chow pellets 7 days/week, whereas the second group was given chow pellets for 5 days and palatable food for 2 days over seven consecutive weeks. Rats were also trained for operant conditioning. Intermittent access to palatable food elicited binging behavior and reduced intake of normal food. Rats with intermittent access to palatable food failed to exhibit anxiety-like behaviors in the elevated plus maze, but displayed reduced locomotor activity in the open field and developed a blunted corticosterone response following an acute stress across the diet procedure. Trained under a progressive ratio schedule, both groups exhibited the same motivation for sweetened food pellets. However, in contrast to controls, rats with a history of dieting and binging exhibited a persistent compulsive-like behavior when access to preferred pellets was paired with mild electrical foot shock punishments. These results highlight the intricate development of anxiety-like disorders and cognitive deficits leading to a loss of control over preferred food intake after repetitive cycles of intermittent access to palatable food.

Dietary sugars: their detection by the gut-brain axis and their peripheral and central effects in health and diseases

Background

Substantial increases in dietary sugar intake together with the increasing prevalence of obesity worldwide, as well as the parallels found between sugar overconsumption and drug abuse, have motivated research on the adverse effects of sugars on health and eating behaviour. Given that the gut–brain axis depends on multiple interactions between peripheral and central signals, and because these signals are interdependent, it is crucial to have a holistic view about dietary sugar effects on health.

Methods

Recent data on the effects of dietary sugars (i.e. sucrose, glucose, and fructose) at both peripheral and central levels and their interactions will be critically discussed in order to improve our understanding of the effects of sugars on health and diseases. This will contribute to the development of more efficient strategies for the prevention and treatment for obesity and associated co-morbidities.

Results

This review highlights opposing effects of glucose and fructose on metabolism and eating behaviour. Peripheral glucose and fructose sensing may influence eating behaviour by sweet-tasting mechanisms in the mouth and gut, and by glucose-sensing mechanisms in the gut. Glucose may impact brain reward regions and eating behaviour directly by crossing the blood–brain barrier, and indirectly by peripheral neural input and by oral and intestinal sweet taste/sugar-sensing mechanisms, whereas those promoted by fructose orally ingested seem to rely only on these indirect mechanisms.

Conclusions

Given the discrepancies between studies regarding the metabolic effects of sugars, more studies using physiological experimental conditions and in animal models closer to humans are needed. Additional studies directly comparing the effects of sucrose, glucose, and fructose should be performed to elucidate possible differences between these sugars on the reward circuitry.

Lifestyle Medicine

As the lifestyle medicine movement continues to gain traction and strength, it is critically important that lifestyle medicine practitioners base their recommendations on the best available evidence. This review outlines ways of accomplishing that goal. The core concepts behind lifestyle medicine reside in many different bodies of information. These include nutrition, exercise physiology, behavioral medicine, psychology, and many more. Lifestyle medicine practitioners will need to be knowledgeable in all of these areas. A good place to start is with the evidence-based recommendations put out by major national bodies. The Dietary Guidelines for Americans and Physical Activity Guidelines for Americans also provide comprehensive, evidence-based information regarding these 2 critically important modalities. This review also discusses ways that scientific information is often distorted and how conjecture may sometimes be confused with proof. The review concludes with some recommendations for how lifestyle medicine practitioners can ground their recommendations on sound scientific evidence.

Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms

Microbes in the gastrointestinal tract are under selective pressure to manipulate host eating behavior to increase their fitness, sometimes at the expense of host fitness. Microbes may do this through two potential strategies: (i) generating cravings for foods that they specialize on or foods that suppress their competitors, or (ii) inducing dysphoria until we eat foods that enhance their fitness. We review several potential mechanisms for microbial control over eating behavior including microbial influence on reward and satiety pathways, production of toxins that alter mood, changes to receptors including taste receptors, and hijacking of the vagus nerve, the neural axis between the gut and the brain. We also review the evidence for alternative explanations for cravings and unhealthy eating behavior. Because microbiota are easily manipulatable by prebiotics, probiotics, antibiotics, fecal transplants, and dietary changes, altering our microbiota offers a tractable approach to otherwise intractable problems of obesity and unhealthy eating.

Combined compared to dissociated oral and intestinal sucrose stimuli induce different brain hedonic processes

The characterization of brain networks contributing to the processing of oral and/or intestinal sugar signals in a relevant animal model might help to understand the neural mechanisms related to the control of food intake in humans and suggest potential causes for impaired eating behaviors. This study aimed at comparing the brain responses triggered by oral and/or intestinal sucrose sensing in pigs. Seven animals underwent brain single photon emission computed tomography (^99mTc-HMPAO) further to oral stimulation with neutral or sucrose artificial saliva paired with saline or sucrose infusion in the duodenum, the proximal part of the intestine. Oral and/or duodenal sucrose sensing induced differential cerebral blood flow changes in brain regions known to be involved in memory, reward processes and hedonic (i.e., pleasure) evaluation of sensory stimuli, including the dorsal striatum, prefrontal cortex, cingulate cortex, insular cortex, hippocampus, and parahippocampal cortex. Sucrose duodenal infusion only and combined sucrose stimulation induced similar activity patterns in the putamen, ventral anterior cingulate cortex and hippocampus. Some brain deactivations in the prefrontal and insular cortices were only detected in the presence of oral sucrose stimulation. Finally, activation of the right insular cortex was only induced by combined oral and duodenal sucrose stimulation, while specific activity patterns were detected in the hippocampus and parahippocampal cortex with oral sucrose dissociated from caloric load. This study sheds new light on the brain hedonic responses to sugar and has potential implications to unravel the neuropsychological mechanisms underlying food pleasure and motivation.

Cognitive and behavioural effects of sugar consumption in rodents. A review

The pronounced global rise in sugar consumption in recent years has been driven largely by increased consumption of sugar-sweetened beverages. Although high sugar intakes are recognised to increase the risk of obesity and related metabolic disturbances, less is known about how sugar might also impair cognition and learned behaviour. This review considers the effects of sugar in rodents on measures of learning and memory, reward processing, anxiety and mood. The parallels between sugar consumption and addictive behaviours are also discussed. The available evidence clearly indicates that sugar consumption can induce cognitive dysfunction. Deficits have been found most consistently on tasks measuring spatial learning and memory. Younger animals appear to be particularly sensitive to the effects of sugar on reward processing, yet results vary according to what reward-related behaviour is assessed. Sugar does not appear to produce long-term effects on anxiety or mood. Importantly, cognitive impairments have been found when intake approximates levels of sugar consumption in people and without changes to weight gain. There remain several caveats when extrapolating from animal models to putative effects of sugar on cognitive function in people. These issues are discussed in conjunction with potential underlying neural mechanisms and directions for future research.

Experiences of barriers and facilitators to weight-loss in a diet intervention - a qualitative study of women in northern Sweden

Background

There is a lack of research about the experiences of participating in weight-reducing interventions. The aim of this study was to explore barriers and facilitators to weight-loss experienced by participants in a diet intervention for middle-aged to older women in the general population in Northern Sweden.

Method

In the intervention the women were randomised to eat either a Palaeolithic-type diet or a diet according to Nordic Nutrition recommendations for 24 months. A strategic selection was made of women from the two intervention groups as well as from the drop-outs in relation to social class, civil status and age. Thematic structured interviews were performed with twelve women and analysed with qualitative content analyses.

Results

The results showed that the women in the dietary intervention experienced two main barriers – struggling with self (related to difficulties in changing food habits, health problems, lack of self-control and insecurity) and struggling with implementing the diet (related to social relations and project-related difficulties) – and two main facilitators– striving for self-determination (related to having clear goals) and receiving support (from family/friends as well as from the project) – for weight-loss. There was a greater emphasis on barriers than on facilitators.

Conclusion

It is important to also include drop-outs from diet interventions in order to fully understand barriers to weight-loss. A gender-relational approach can bring new insights into understanding experiences of barriers to weight-loss.

Trial registration

ClinicalTrials gov NCT00692536.