Refined food addiction: A classic substance use disorder

Food addiction symptomology, impulsivity, mood, and body mass index in people with type two diabetes

This research explored how food addiction (FA) and impulsivity (non-planning, motor, and attentional) relate to body mass index (BMI) in a sample of people with type 2 diabetes (t2d). Participants with t2d (N = 334, Mage = 41.0, SDage = 9.5, 66% female, MBMI = 37.6 kg/m(2), SDBMI = 8.0 kg/m(2)) completed an online survey including the Depression Anxiety Stress Scale (DASS-21), the Barratt Impulsiveness Scale (BIS-II), and the Yale Food Addiction Scale (YFAS). Results demonstrated that over 70% of the sample with t2d met the YFAS criteria for FA. Results also demonstrated that participants classified as FA had significantly higher BMI, t (332) = 12.11, p < .001. The food addict classification group also had a significantly higher percentage of obese participants, χ(2) (2) = 87.1, p < .001, phi = .511. Utilising a cross-sectional design to predict BMI, significant forward stepwise multiple regression demonstrated that FA (β = .386) and impulsivity (non-planning) (β = .286) were significant predictors. In combination FA and impulsivity (non-planning) significantly explained 38% of BMI variance; however depression, anxiety, and stress did not significantly improve the model. These results suggest FA and impulsivity (non-planning) are more salient cross-sectional predictors of BMI, in people with t2d, than indices of depression, anxiety, stress and impulsivity (motor and attentional). These results, implicating FA in the development of obesity, have important ramifications for potential future treatment methods of t2d where FA symptomology could be routinely screened, and if present, treated via addiction models rather than purely attempting to treat the potential consequences of FA.

Obesity and the neurocognitive basis of food reward and the control of intake

With the rising prevalence of obesity, hedonic eating has become an important theme in obesity research. Hedonic eating is thought to be that driven by the reward of food consumption and not metabolic need, and this has focused attention on the brain reward system and how its dysregulation may cause overeating and obesity. Here, we begin by examining the brain reward system and the evidence for its dysregulation in human obesity. We then consider the issue of how individuals are able to control their hedonic eating in the present obesogenic environment and compare 2 contrasting perspectives on the control of hedonic eating, specifically, enhanced control of intake via higher cognitive control and loss of control over intake as captured by the food addiction model. We conclude by considering what these perspectives offer in terms of directions for future research and for potential interventions to improve control over food intake at the population and the individual levels.

[Food addiction - substance use disorder or behavioral addiction?]

This article looks at food addiction as a subject situated between psychiatry, neurobiology, nutritional science, internal medicine, food industry, and public health. Essentially, the question is whether or not individual nutritional components can induce physical dependence, similar to the well-known effects of drugs such as alcohol and cocaine, or whether food addiction is rather a behavioral addiction. The literature describes many overlaps as well as differences of substance-based and non-substance-based addiction in both clinical and neurobiological terms. Until recently it was argued that food addiction appears only in the realms of obesity and eating disorders (e.g., binge-eating disorder, BED). Some studies, however, described the prevalence of food addiction symptoms and diagnoses independent of overweight or that they were in subjects who do not fulfill the criteria for BED. This article sums up the controversial discussion about the phenomenological and neurobiological classification of food addiction. Implications of food addiction for children and adolescents as well as public-health-related issues are also discussed.

Foods and dietary profiles associated with 'food addiction' in young adults

Background

It has been suggested that addictive behaviors related to consumption of specific foods could contribute to overeating and obesity. Although energy-dense, hyper-palatable foods are hypothesized to be associated with addictive-like eating behaviors, few studies have assessed this in humans.

Objective

To evaluate in young adults whether intakes of specific foods are associated with ‘food addiction’, as assessed by the Yale Food Addiction Scale (YFAS), and to describe the associated nutrient intake profiles.

Design

Australian adults aged 18–35 years were invited to complete an online cross-sectional survey including demographics, the YFAS and usual dietary intake. Participants were classified as food addicted (FAD) or non-addicted (NFA) according to the YFAS predefined scoring criteria.

Results

A total 462 participants (86% female, 73% normal weight) completed the survey, with 14.7% (n = 68) classified as FAD. The FAD group had a higher proportion of females (p = .01) and higher body mass index (p < .001) compared to NFA. Higher YFAS symptom scores were associated with higher percentage energy intake (%E) from energy-dense, nutrient-poor foods including candy, take out and baked sweet products, as well as lower %E from nutrient-dense core foods including whole-grain products and breakfast cereals. These remained statistically significant when adjusted for age, sex and BMI category (p = .001).

Conclusions

Statistically significant associations were identified between YFAS assessed food addiction and dietary intake, specifically intakes of energy-dense, nutrient-poor foods. However, the effect sizes were small limiting clinical applications. Further examination of the relationship between addictive-like eating and intake of specific foods in a nationally representative sample is warranted.

•

14.7% participants met the YFAS predefined criteria for food addiction.

•

Those classified as food addicted had a significantly higher body mass index.

•

Higher symptom scores related to higher intakes of energy-dense nutrient-poor foods

•

Lower odds of YFAS assessed food addiction with higher intakes of whole-grains.

•

Higher odds of YFAS assessed food addiction with higher intakes of dietary fat.

Treatment of child/adolescent obesity using the addiction model: a smartphone app pilot study

BACKGROUND

The aim of this study was to test a weight loss program for young people based on an addiction treatment approach.

METHODS

A pilot study (n=43) was conducted of a 20-week child/adolescent obesity intervention based on an addiction treatment model (staged, incremental withdrawal from problem foods, snacking/grazing, and excessive amounts at meals) and implemented by a server-integrated smartphone app with health professional support. The primary outcome was standardized %overBMI measured at four time points. Secondary outcomes were participants' self-ratings of self-esteem, control over food, and the degree they turned to food when stressed. User satisfaction data were collected with an online questionnaire. Latent growth modeling techniques were used to identify independent variables and possible mediating treatment process variables associated with weight change.

RESULTS

Mean age of participants was 16 years (range, 10-21), 65% girls, and 84% Caucasian. Twenty-seven (63%) completed the program. There was a significant decrease in %overBMI over time of 7.1. There were significant improvements in participant ratings of self-esteem, control over food, and a reduction in turning to food when stressed. Males, younger participants, and participants with higher levels of program compliance achieved better weight loss. Participants who reported that calling obesity an addiction made their guilt worse experienced poorer weight loss. Females were more likely than males to report "addiction guilt," and this partly mediated the overall gender effect.

CONCLUSIONS

The staged, incremental food withdrawal approach was feasible to implement and was useful in helping reduce excessive weight, particularly among boys.

Fructose:glucose ratios--a study of sugar self-administration and associated neural and physiological responses in the rat

This study explored whether different ratios of fructose (F) and glucose (G) in sugar can engender significant differences in self-administration and associated neurobiological and physiological responses in male Sprague-Dawley rats. In Experiment 1, animals self-administered pellets containing 55% F + 45% G or 30% F + 70% G, and Fos immunoreactivity was assessed in hypothalamic regions regulating food intake and reward. In Experiment 2, rats self-administered solutions of 55% F + 42% G (high fructose corn syrup (HFCS)), 50% F + 50% G (sucrose) or saccharin, and mRNA of the dopamine 2 (D2R) and mu-opioid (MOR) receptor genes were assessed in striatal regions involved in addictive behaviors. Finally, in Experiment 3, rats self-administered HFCS and sucrose in their home cages, and hepatic fatty acids were quantified. It was found that higher fructose ratios engendered lower self-administration, lower Fos expression in the lateral hypothalamus/arcuate nucleus, reduced D2R and increased MOR mRNA in the dorsal striatum and nucleus accumbens core, respectively, as well as elevated omega-6 polyunsaturated fatty acids in the liver. These data indicate that a higher ratio of fructose may enhance the reinforcing effects of sugar and possibly lead to neurobiological and physiological alterations associated with addictive and metabolic disorders.

Trends in consumption of ultra-processed foods and obesity in Sweden between 1960 and 2010

Objective

To investigate how consumption of ultra-processed foods has changed in Sweden in relation to obesity.

Design

Nationwide ecological analysis of changes in processed foods along with corresponding changes in obesity. Trends in per capita food consumption during 1960–2010 were investigated using data from the Swedish Board of Agriculture. Food items were classified as group 1 (unprocessed/minimally processed), group 2 (processed culinary ingredients) or group 3 (3·1, processed food products; and 3·2, ultra-processed products). Obesity prevalence data were pooled from the peer-reviewed literature, Statistics Sweden and the WHO Global Health Observatory.

Setting

Nationwide analysis in Sweden, 1960–2010.

Subjects

Swedish nationals aged 18 years and older.

Results

During the study period consumption of group 1 foods (minimal processing) decreased by 2 %, while consumption of group 2 foods (processed ingredients) decreased by 34 %. Consumption of group 3·1 foods (processed food products) increased by 116 % and group 3·2 foods (ultra-processed products) increased by 142 %. Among ultra-processed products, there were particularly large increases in soda (315 %; 22 v. 92 litres/capita per annum) and snack foods such as crisps and candies (367 %; 7 v. 34 kg/capita per annum). In parallel to these changes in ultra-processed products, rates of adult obesity increased from 5 % in 1980 to over 11 % in 2010.

Conclusions

The consumption of ultra-processed products (i.e. foods with low nutritional value but high energy density) has increased dramatically in Sweden since 1960, which mirrors the increased prevalence of obesity. Future research should clarify the potential causal role of ultra-processed products in weight gain and obesity.

Putting your money where your mouth is: why sustainability reporting based on the triple bottom line can be misleading

In the packaged food industry, Corporate Social Responsibility (CSR) is an informal requirement for which firms account through sustainability reporting. CSR behaviors are often reported and analyzed using the Triple Bottom Line (3BL) framework, which categorizes them as affecting people, planet, or profit. 3BL is useful in determining which of these categories is most elaborated upon by the firm, but has a limited scope and many documented criticisms. This paper aims to address the aforementioned insufficiencies by augmenting the 3BL framework with two important attributes of CSR practices: (1) the presence of change in core firm behavior of the firm itself or of others in the supply chain, and (2) whether the behavior qualifies as being outside of the firm’s normal business practice or is something that they might have done anyway. We qualitatively analyze CSR behaviors described in sustainability reports and interviews from major players in the packaged food industry and categorize them using these attributes as a supplement to 3BL. This enables us to separate the behaviors from their framing and analyze them more critically. Our results demonstrate how the visible CSR efforts of a firm can be misleading at first glance. Using only 3BL, we find that the CSR focus of firms in this industry is people. We then discover that the codes focusing on people (as opposed to planet or profit) require the least amount of real structural change from a firm or its supply chain partners, and thus arguably, the least amount of effort. We also find that behaviors that focus on planet require the most effort within the firm itself, but for behaviors involving supply chain partners, effort is required for behaviors in all three categories. Finally, we find that CSR behavior that is related to planet tends to go beyond normal business practice.

When chocolate seeking becomes compulsion: gene-environment interplay

BACKGROUND

Eating disorders appear to be caused by a complex interaction between environmental and genetic factors, and compulsive eating in response to adverse circumstances characterizes many eating disorders.

MATERIALS AND METHODS

We compared compulsion-like eating in the form of conditioned suppression of palatable food-seeking in adverse situations in stressed C57BL/6J and DBA/2J mice, two well-characterized inbred strains, to determine the influence of gene-environment interplay on this behavioral phenotype. Moreover, we tested the hypothesis that low accumbal D2 receptor (R) availability is a genetic risk factor of food compulsion-like behavior and that environmental conditions that induce compulsive eating alter D2R expression in the striatum. To this end, we measured D1R and D2R expression in the striatum and D1R, D2R and α1R levels in the medial prefrontal cortex, respectively, by western blot.

RESULTS

Exposure to environmental conditions induces compulsion-like eating behavior, depending on genetic background. This behavioral pattern is linked to decreased availability of accumbal D2R. Moreover, exposure to certain environmental conditions upregulates D2R and downregulates α1R in the striatum and medial prefrontal cortex, respectively, of compulsive animals. These findings confirm the function of gene-environment interplay in the manifestation of compulsive eating and support the hypothesis that low accumbal D2R availability is a "constitutive" genetic risk factor for compulsion-like eating behavior. Finally, D2R upregulation and α1R downregulation in the striatum and medial prefrontal cortex, respectively, are potential neuroadaptive responses that parallel the shift from motivated to compulsive eating.

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.

Metabolic vs. hedonic obesity: a conceptual distinction and its clinical implications

Body weight is determined via both metabolic and hedonic mechanisms. Metabolic regulation of body weight centres around the 'body weight set point', which is programmed by energy balance circuitry in the hypothalamus and other specific brain regions. The metabolic body weight set point has a genetic basis, but exposure to an obesogenic environment may elicit allostatic responses and upward drift of the set point, leading to a higher maintained body weight. However, an elevated steady-state body weight may also be achieved without an alteration of the metabolic set point, via sustained hedonic over-eating, which is governed by the reward system of the brain and can override homeostatic metabolic signals. While hedonic signals are potent influences in determining food intake, metabolic regulation involves the active control of both food intake and energy expenditure. When overweight is due to elevation of the metabolic set point ('metabolic obesity'), energy expenditure theoretically falls onto the standard energy-mass regression line. In contrast, when a steady-state weight is above the metabolic set point due to hedonic over-eating ('hedonic obesity'), a persistent compensatory increase in energy expenditure per unit metabolic mass may be demonstrable. Recognition of the two types of obesity may lead to more effective treatment and prevention of obesity.

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.

Eating Disorders in Late-life

Eating disorders are a heterogeneous group of complex psychiatric disorders characterized by abnormal eating behaviours that lead to a high rate of morbidity, or even death, if underestimated and untreated. The main disorders enlisted in the chapter of the Diagnostic and Statistic Manual of Mental Disorders-5 dedicated to "Feeding and Eating Disorders" are: anorexia nervosa, bulimia nervosa and binge eating disorder. Even though these abnormal behaviours are mostly diagnosed during childhood, interesting cases of late-life eating disorders have been reported in literature. In this review, these eating disorders are discussed, with particular attention to the diagnosis and management of those cases occurring in late-life.

Obesity: pathophysiology and intervention

Obesity presents a major health hazard of the 21st century. It promotes co-morbid diseases such as heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis. Excessive energy intake, physical inactivity, and genetic susceptibility are main causal factors for obesity, while gene mutations, endocrine disorders, medication, or psychiatric illnesses may be underlying causes in some cases. The development and maintenance of obesity may involve central pathophysiological mechanisms such as impaired brain circuit regulation and neuroendocrine hormone dysfunction. Dieting and physical exercise offer the mainstays of obesity treatment, and anti-obesity drugs may be taken in conjunction to reduce appetite or fat absorption. Bariatric surgeries may be performed in overtly obese patients to lessen stomach volume and nutrient absorption, and induce faster satiety. This review provides a summary of literature on the pathophysiological studies of obesity and discusses relevant therapeutic strategies for managing obesity.

Animal models of compulsive eating behavior

Eating disorders are multifactorial conditions that can involve a combination of genetic, metabolic, environmental, and behavioral factors. Studies in humans and laboratory animals show that eating can also be regulated by factors unrelated to metabolic control. Several studies suggest a link between stress, access to highly palatable food, and eating disorders. Eating "comfort foods" in response to a negative emotional state, for example, suggests that some individuals overeat to self-medicate. Clinical data suggest that some individuals may develop addiction-like behaviors from consuming palatable foods. Based on this observation, "food addiction" has emerged as an area of intense scientific research. A growing body of evidence suggests that some aspects of food addiction, such as compulsive eating behavior, can be modeled in animals. Moreover, several areas of the brain, including various neurotransmitter systems, are involved in the reinforcement effects of both food and drugs, suggesting that natural and pharmacological stimuli activate similar neural systems. In addition, several recent studies have identified a putative connection between neural circuits activated in the seeking and intake of both palatable food and drugs. The development of well-characterized animal models will increase our understanding of the etiological factors of food addiction and will help identify the neural substrates involved in eating disorders such as compulsive overeating. Such models will facilitate the development and validation of targeted pharmacological therapies.

Pharmacological means of reducing human drug dependence: a selective and narrative review of the clinical literature

Substance abuse or addictive disorder is a global problem. A greater understanding of the associated changes in brain pathophysiology supports the notion that pharmacological treatments are part of the necessary treatment options. Craving is a core symptom of addictive disorder. It refers to a strong desire to use drugs again either to re-experience positive effects or to diminish negative experiences. Currently there are a number of medicines that are effective in the treatment of addictive disorders. These medications can either be for substitution (same pharmacological effect as the abused substance) or anticraving (decrease the craving of the abused substance). In this MEDLNE based review, specific compounds (naltrexone, acamprosate, topiramate, disulfiram, baclofen, N-acetylcysteine and bupropion) were selected that are known to diminish desire to use (anticraving effect) and that have been trialled for a number of different substance addictive disorders. Their therapeutic potential in clinical practice is discussed in light of their efficacy.

Food addiction in the light of DSM-5

The idea that specific kind of foods may have an addiction potential and that some forms of overeating may represent an addicted behavior has been discussed for decades. In recent years, the interest in food addiction is growing and research on this topic lead to more precise definitions and assessment methods. For example, the Yale Food Addiction Scale has been developed for the measurement of addiction-like eating behavior based on the diagnostic criteria for substance dependence of the fourth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). In 2013, diagnostic criteria for substance abuse and-dependence were merged, thereby increasing the number of symptoms for substance use disorders (SUDs) in the DSM-5. Moreover, gambling disorder is now included along SUDs as a behavioral addiction. Although a plethora of review articles exist that discuss the applicability of the DSM-IV substance dependence criteria to eating behavior, the transferability of the newly added criteria to eating is unknown. Thus, the current article discusses if and how these new criteria may be translated to overeating. Furthermore, it is examined if the new SUD criteria will impact future research on food addiction, for example, if "diagnosing" food addiction should also be adapted by considering all of the new symptoms. Given the critical response to the revisions in DSM-5, we also discuss if the recent approach of Research Domain Criteria can be helpful in evaluating the concept of food addiction.

Neural responses to visual food cues according to weight status: a systematic review of functional magnetic resonance imaging studies

Emerging evidence from recent neuroimaging studies suggests that specific food-related behaviors contribute to the development of obesity. The aim of this review was to report the neural responses to visual food cues, as assessed by functional magnetic resonance imaging (fMRI), in humans of differing weight status. Published studies to 2014 were retrieved and included if they used visual food cues, studied humans >18 years old, reported weight status, and included fMRI outcomes. Sixty studies were identified that investigated the neural responses of healthy weight participants (n = 26), healthy weight compared to obese participants (n = 17), and weight-loss interventions (n = 12). High-calorie food images were used in the majority of studies (n = 36), however, image selection justification was only provided in 19 studies. Obese individuals had increased activation of reward-related brain areas including the insula and orbitofrontal cortex in response to visual food cues compared to healthy weight individuals, and this was particularly evident in response to energy dense cues. Additionally, obese individuals were more responsive to food images when satiated. Meta-analysis of changes in neural activation post-weight loss revealed small areas of convergence across studies in brain areas related to emotion, memory, and learning, including the cingulate gyrus, lentiform nucleus, and precuneus. Differential activation patterns to visual food cues were observed between obese, healthy weight, and weight-loss populations. Future studies require standardization of nutrition variables and fMRI outcomes to enable more direct comparisons between studies.

Addiction to sugar and its link to health morbidity: a primer for newer primary care and public health initiatives in Malaysia

OBJECTIVES

The average consumption of sugar in the Malaysian population has reached an alarming rate, exceeding the benchmark recommended by experts. This article argues the need of a paradigm shift in the management of sugar consumption in the country through evidence derived from addiction research.

METHODS

"Food addiction" could lead to high levels of sugar consumption. This probable link could accelerate the development of diabetes and obesity in the community. A total of 94 reports and studies that describe the importance of addiction theory-based interventions were found through a search on PubMed, Google Scholar, and Academic Search Complete.

RESULTS

Research in the field of addiction medicine has revealed the addictive potential of high levels of sugar intake. Preexisting health promotion strategies could benefit from the integration of the concept of sugar addiction. A targeted intervention could yield more positive results in health outcomes within the country.

CONCLUSION

Current literature seems to support food environment changes, targeted health policies, and special consultation skills as cost-effective remedies to curb the rise of sugar-related health morbidities.

Validation of the French version of the yale food addiction scale: an examination of its factor structure, reliability, and construct validity in a nonclinical sample

OBJECTIVE

The concept of food addiction has recently been proposed by applying the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria for substance dependence to eating behaviour. Food addiction has received increased attention given that it may play a role in binge eating, eating disorders, and the recent increase in obesity prevalence. Currently, there is no psychometrically sound tool for assessing food addiction in French. Our study aimed to test the psychometric properties of a French version of the Yale Food Addiction Scale (YFAS) by establishing its factor structure and construct validity in a nonclinical population.

METHOD

A total of 553 participants were assessed for food addiction (French version of the YFAS) and binge eating behaviour (Bulimic Investigatory Test Edinburgh and Binge Eating Scale). We tested the scale's factor structure (factor analysis for dichotomous data based on tetrachoric correlation coefficients), internal consistency, and construct validity with measures of binge eating.

RESULTS

Our results supported a 1-factor structure, which accounted for 54.1% of the variance. This tool had adequate reliability and high construct validity with measures of binge eating in this population, both in its diagnosis and symptom count version. A 2-factor structure explained an additional 9.1% of the variance, and could differentiate between patients with high, compared with low, levels of insight regarding addiction symptoms.

CONCLUSIONS

In our study, we validated a psychometrically sound French version of the YFAS, both in its symptom count and diagnostic version. Future studies should validate this tool in clinical samples.

A novel procedure for evaluating the reinforcing properties of tastants in laboratory rats: operant intraoral self-administration

This paper describes a novel method for studying the bio-behavioral basis of addiction to food. This method combines the surgical component of taste reactivity with the behavioral aspects of operant self-administration of drugs. Under very brief general anaesthesia, rats are implanted with an intraoral (IO) cannula that allows delivery of test solutions directly in the oral cavity. Animals are then tested in operant self-administration chambers whereby they can press a lever to receive IO infusions of test solutions. IO self-administration has several advantages over experimental procedures that involve drinking a solution from a spout or operant responding for solid pellets or solutions delivered in a receptacle. Here, we show that IO self-administration can be employed to study self-administration of high fructose corn syrup (HFCS). Rats were first tested for self-administration on a progressive ratio (PR) schedule, which assesses the maximum amount of operant behavior that will be emitted for different concentrations of HFCS (i.e. 8%, 25%, and 50%). Following this test, rats self-administered these concentrations on a continuous schedule of reinforcement (i.e. one infusion for each lever press) for 10 consecutive days (1 session/day; each lasting 3 hr), and then they were retested on the PR schedule. On the continuous reinforcement schedule, rats took fewer infusions of higher concentrations, although the lowest concentration of HFCS (8%) maintained more variable self-administration. Furthermore, the PR tests revealed that 8% had lower reinforcing value than 25% and 50%. These results indicate that IO self-administration can be employed to study acquisition and maintenance of responding for sweet solutions. The sensitivity of the operant response to differences in concentration and schedule of reinforcement makes IO self-administration an ideal procedure to investigate the neurobiology of voluntary intake of sweets.

A novel procedure for evaluating the reinforcing properties of tastants in laboratory rats: operant intraoral self-administration

This paper describes a novel method for studying the bio-behavioral basis of addiction to food. This method combines the surgical component of taste reactivity with the behavioral aspects of operant self-administration of drugs. Under very brief general anaesthesia, rats are implanted with an intraoral (IO) cannula that allows delivery of test solutions directly in the oral cavity. Animals are then tested in operant self-administration chambers whereby they can press a lever to receive IO infusions of test solutions. IO self-administration has several advantages over experimental procedures that involve drinking a solution from a spout or operant responding for solid pellets or solutions delivered in a receptacle. Here, we show that IO self-administration can be employed to study self-administration of high fructose corn syrup (HFCS). Rats were first tested for self-administration on a progressive ratio (PR) schedule, which assesses the maximum amount of operant behavior that will be emitted for different concentrations of HFCS (i.e. 8%, 25%, and 50%). Following this test, rats self-administered these concentrations on a continuous schedule of reinforcement (i.e. one infusion for each lever press) for 10 consecutive days (1 session/day; each lasting 3 hr), and then they were retested on the PR schedule. On the continuous reinforcement schedule, rats took fewer infusions of higher concentrations, although the lowest concentration of HFCS (8%) maintained more variable self-administration. Furthermore, the PR tests revealed that 8% had lower reinforcing value than 25% and 50%. These results indicate that IO self-administration can be employed to study acquisition and maintenance of responding for sweet solutions. The sensitivity of the operant response to differences in concentration and schedule of reinforcement makes IO self-administration an ideal procedure to investigate the neurobiology of voluntary intake of sweets.

Comparing effects of carbohydrate (CHO) blockers and trivalent chromium on CHO-induced insulin resistance and elevated blood pressure in rats

OBJECTIVE

In Sprague-Dawley rats (SD), we compared two categories of natural dietary supplements that influence carbohydrate (CHO) metabolism via different basic mechanisms to ameliorate insulin resistance (IR) and elevated blood pressure (BP) associated with heavy sugar/starch consumption. Two dietary supplements (bean extract and l-arabinose) are often referred to as carb blockers (CBs), because they slow the gastrointestinal absorption of CHO. Trivalent chromium (CR) falls into a group of so-called insulin sensitizers, because its major effect is to enhance peripheral insulin sensitivity.

METHOD

We divided 48 mature male SD into 4 groups of 12. The first group received powdered baseline diet alone (Con). The remaining 3 SD groups (groups 2-4) ingested regular rat chow containing 20% w/w sucrose and 20% w/w rice starch. The second group received only this CHO-enriched chow. To the high-CHO diets of the remaining two groups, either CB to slow CHO absorption (CHO + CB) (group 3) or an insulin sensitizer, trivalent CR (CHO + CR; group 4), was added.

RESULTS

Compared to Con group 1, adding high CHO content to the diet of group 2 significantly increased circulating glucose levels and systolic BP (SBP). Addition of CB or CR to the feed of groups 3 and 4 overcame the perturbations that occurred with high CHO challenge in group 2; that is, they lowered circulating glucose concentrations to Con levels, enhanced response to exogenous insulin, and overcame the gradual elevation of SBP. Compared to group 2, the two treatment groups (3 and 4) also showed decreased renin-angiotensin system activity, decreased serum angiotensin-converting enzyme activity, and enhanced nitric oxide activity.

CONCLUSIONS

Our data indicate that high doses of CB and CR, despite their different mechanisms of action, can completely overcome CHO-induced IR and BP elevations. The data further suggest that CB and CR affect only the changes brought on by heavy CHO ingestion, because IR and SBP in groups 3 and 4 mirrored Con values (group 1), never producing values lower than baseline. Earlier use of CB and CR in the life cycle appears more effective in overcoming CHO-induced perturbations than later use.

A qualitative study of binge eating and obesity from an addiction perspective

The purpose of this study was to explore how obese women with and without binge eating disorder (BED) experience overeating in relation to the DSM-5 symptoms of addiction. Findings from this study demonstrate that food addiction can occur in obese individuals with and without BED. It is important that health care professionals identify individuals who may require a specific treatment approach that incorporates techniques used in the treatment of addictions.

The overlap between binge eating disorder and substance use disorders: Diagnosis and neurobiology

BACKGROUND AND AIMS

Binge eating disorder (BED) is a relatively common condition, especially in young adult females, and is characterized by chronic over-consumption of food resulting in embarrassment, distress, and potential health problems. It is formally included as a disorder in DSM-5 for the first time, an acknowledgement to its debilitating nature. This article explores the overlap between binge eating disorder and substance use disorders (SUD).

METHODS

The bibliographic search was a computerized screen of PubMed databases from January 1990 to the present. Binge eating disorder, substance use disorder, binging, obesity, food addiction, comorbidity, dopamine, opioid, serotonin, glutamate, and pharmacological treatment were the keywords used in searching.

RESULTS

BED shares similar phenomenology to SUD, including significant urges to engage in binging episodes, resulting in distress and impairment. Similar neurobiological pathways are found in both BED and SUD and medications based on similar neurobiology have been examined for both disorders. A subset of individuals with BED may have a "food addiction", but there is no clinical agreement on the meaning of "food addiction". Exploring the relationship between BED and obesity may also shed light on the extent to which BED can be viewed as an addiction.

CONCLUSIONS

Overall, nascent research regarding BED and SUD suggests an overlap between these disorders, but there are discrepancies between these two disorders that need further exploration.

Food addiction: its prevalence and significant association with obesity in the general population

Background

‘Food addiction’ shares a similar neurobiological and behavioral framework with substance addiction. However whether, and to what degree, ‘food addiction’ contributes to obesity in the general population is unknown.

Objectives

to assess 1) the prevalence of ‘food addiction’ in the Newfoundland population; 2) if clinical symptom counts of ‘food addiction’ were significantly correlated with the body composition measurements; 3) if food addicts were significantly more obese than controls, and 4) if macronutrient intakes are associated with ‘food addiction’.

Design

A total of 652 adults (415 women, 237 men) recruited from the general population participated in this study. Obesity was evaluated by Body Mass Index (BMI) and Body Fat percentage measured by dual-energy X-ray absorptiometry. ‘Food addiction’ was assessed using the Yale Food Addiction Scale and macronutrient intake was determined from the Willet Food Frequency Questionnaire.

Results

The prevalence of ‘food addiction’ was 5.4% (6.7% in females and 3.0% in males) and increased with obesity status. The clinical symptom counts of ‘food addiction’ were positively correlated with all body composition measurements across the entire sample (p<0.001). Obesity measurements were significantly higher in food addicts than controls; Food addicts were 11.7 (kg) heavier, 4.6 BMI units higher, and had 8.2% more body fat and 8.5% more trunk fat. Furthermore, food addicts consumed more calories from fat and protein compared with controls.

Conclusion

Our results demonstrated that ‘food addiction’ contributes to severity of obesity and body composition measurements from normal weight to obese individuals in the general population with higher rate in women as compared to men.

Co-sensitivity to the incentive properties of palatable food and cocaine in rats; implications for co-morbid addictions

Several lines of evidence suggest that there may be a shared vulnerability to acquire behaviors motivated by strong incentive stimuli. Non-food restricted male Sprague-Dawley rats (n = 78) underwent place conditioning with Oreos, and were subsequently tested on cocaine self-administration (SA) on fixed and progressive ratios, as well as extinction and reinstatement by cocaine primes and by consumption of Oreos. Although there was a group preference for the Oreo-paired compartment, at the individual level some rats (69%) displayed a preference and others did not. In cocaine SA, 'preference' rats achieved higher break points on a progressive ratio, and displayed greater responding during extinction and cocaine-induced reinstatement. Within the context of this study, Oreo-cocaine cross-reinstatement was not observed. In a control study, rats (n = 29) conditioned with a less palatable food (rice cakes) also displayed individual differences in place preference, but not on subsequent cocaine tests. These findings indicate that there is a relationship between incentive learning promoted by palatable foods and by cocaine. This supports the hypothesis that co-morbid food-drug addictions may result from a shared vulnerability to acquire behaviors motivated by strong incentives.

Participacao crescente de produtos ultraprocessados na dieta brasileira (1987-2009)

OBJETIVO Estimar tendências temporais do consumo domiciliar de itens alimentícios no Brasil, levando em conta a extensão e o propósito do seu processamento industrial. MÉTODOS Os dados analisados são provenientes de Pesquisa de Orçamentos Familiares realizadas no Brasil em 1987-1988, 1995-1996, 2002-2003 e 2008-2009. Foram analisadas amostras probabilísticas dos domicílios das áreas metropolitanas em todos os períodos mencionados e, nas duas amostras mais recentes, a abrangência foi nacional. As unidades de análise foram registros de aquisições de agregados de domicílios. Os itens alimentícios foram divididos segundo extensão e propósito de seu processamento industrial em: alimentos in natura ou minimamente processados, ingredientes culinários processados e produtos alimentícios prontos para consumo, processados ou ultraprocessados. A quantidade adquirida de cada item foi convertida em energia. Estimaram-se a disponibilidade diária total per capita de calorias e a contribuição dos grupos de alimentos em cada pesquisa. Calcularam-se estimativas por quintos de renda para as pesquisas nacionais. Variações temporais foram testadas por teste de diferença de médias e modelos de regressão linear. RESULTADOS Houve aumento significativo da participação de produtos prontos para o consumo (de 23,0% para 27,8% das calorias), graças ao aumento no consumo de produtos ultraprocessados (de 20,8% para 25,4%) entre 2002-2003 e 2008-2009. Houve redução significativa na participação de alimentos e de ingredientes culinários nesse período. O aumento da participação de produtos ultraprocessados ocorreu em todos os estratos de renda. Observou-se aumento uniforme da participação calórica de produtos prontos para o consumo em áreas metropolitanas, novamente à custa de produtos ultraprocessados e acompanhada por reduções na participação de alimentos in natura ou minimamente processados quanto de ingredientes culinários. CONCLUSÕES Produtos ultraprocessados apresentam participação crescente na dieta brasileira, evidenciada desde a década de 1980 nas áreas metropolitanas e confirmada para todo o País na década de 2000.

Biological mechanisms that promote weight regain following weight loss in obese humans

Weight loss dieting remains the treatment of choice for the vast majority of obese individuals, despite the limited long-term success of behavioral weight loss interventions. The reasons for the near universal unsustainability of behavioral weight loss in [formerly] obese individuals have not been fully elucidated, relegating researchers to making educated guesses about how to improve obesity treatment, as opposed to developing interventions targeting the causes of weight regain. This article discusses research on several factors that may contribute to weight regain following weight loss achieved through behavioral interventions, including adipose cellularity, endocrine function, energy metabolism, neural responsivity, and addiction-like neural mechanisms. All of these mechanisms are engaged prior to weight loss, suggesting that these so called "anti-starvation" mechanisms are activated via reductions in energy intake, rather than depletion of energy stores. Evidence suggests that these mechanisms are not necessarily part of a homeostatic feedback system designed to regulate body weight, or even anti-starvation mechanisms per se. Although they may have evolved to prevent starvation, they appear to be more accurately described as anti-weight loss mechanisms, engaged with caloric restriction irrespective of the adequacy of energy stores. It is hypothesized that these factors may combine to create a biological disposition that fosters the maintenance of an elevated body weight and works to restore the highest sustained body weight, thus precluding the long-term success of behavioral weight loss. It may be necessary to develop interventions that attenuate these biological mechanisms in order to achieve long-term weight reduction in obese individuals.

Caloric restriction increases the sensitivity to the hyperphagic effect of nociceptin/orphanin FQ limiting its ability to reduce binge eating in female rats

RATIONALE

Nociceptin/orphanin FQ (N/OFQ) is a functional antagonist of corticotrophin-releasing factor, the main mediator of the stress response. Stress represents a key determinant of binge eating (BE) for highly palatable food (HPF).

OBJECTIVES

In relation to the antistress properties of N/OFQ, we evaluated its effect on BE. After the observation that episodes of food restriction increase the sensitivity to its hyperphagic effects, the function of NOP receptor and N/OFQ was investigated after cycles of food restrictions.

MATERIALS AND METHODS

In BE experiments, four groups were used: rats fed normally and not stressed or stressed, rats exposed to cycles of restriction/refeeding and then stressed, or not stressed. In the other experiments, two groups were used: rats exposed or not to food restriction.

RESULTS

Only restricted and stressed rats exhibited BE for HPF (containing chocolate cream). Intracerebroventricular injections of N/OFQ of 0.5 nmol/rat significantly reduced BE. N/OFQ 1 nmol/rat did not reduce BE but significantly increased HPF intake following food restrictions. Cycles of food restriction increased animals' sensitivity to the hyperphagic effect of N/OFQ for HPF. In situ hybridization studies following food restrictions showed decreased ppN/OFQ mRNA expression in the bed nucleus of the stria terminalis and increased expression of ppN/OFQ and NOP receptor mRNA in the ventral tegmental area and in the ventromedial hypothalamus, respectively.

CONCLUSIONS

These findings indicate that N/OFQ slightly reduces BE at low doses, while higher doses increase HPF intake, due to increased sensitivity to its hyperphagic effect following a history of caloric restrictions.

Sugar addiction: pushing the drug-sugar analogy to the limit

PURPOSE OF REVIEW

To review research that tests the validity of the analogy between addictive drugs, like cocaine, and hyperpalatable foods, notably those high in added sugar (i.e., sucrose).

RECENT FINDINGS

Available evidence in humans shows that sugar and sweetness can induce reward and craving that are comparable in magnitude to those induced by addictive drugs. Although this evidence is limited by the inherent difficulty of comparing different types of rewards and psychological experiences in humans, it is nevertheless supported by recent experimental research on sugar and sweet reward in laboratory rats. Overall, this research has revealed that sugar and sweet reward can not only substitute to addictive drugs, like cocaine, but can even be more rewarding and attractive. At the neurobiological level, the neural substrates of sugar and sweet reward appear to be more robust than those of cocaine (i.e., more resistant to functional failures), possibly reflecting past selective evolutionary pressures for seeking and taking foods high in sugar and calories.

SUMMARY

The biological robustness in the neural substrates of sugar and sweet reward may be sufficient to explain why many people can have difficultly to control the consumption of foods high in sugar when continuously exposed to them.

Altered functional brain networks in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a genetic imprinting disorder characterized mainly by hyperphagia and early childhood obesity. Previous functional neuroimaging studies used visual stimuli to examine abnormal activities in the eating-related neural circuitry of patients with PWS. It was found that patients with PWS exhibited both excessive hunger and hyperphagia consistently, even in situations without any food stimulation. In the present study, we employed resting-state functional MRI techniques to investigate abnormal brain networks related to eating disorders in children with PWS. First, we applied amplitude of low-frequency fluctuation analysis to define the regions of interest that showed significant alterations in resting-state brain activity levels in patients compared with their sibling control group. We then applied a functional connectivity (FC) analysis to these regions of interest in order to characterize interactions among the brain regions. Our results demonstrated that patients with PWS showed decreased FC strength in the medial prefrontal cortex (MPFC)/inferior parietal lobe (IPL), MPFC/precuneus, IPL/precuneus and IPL/hippocampus in the default mode network; decreased FC strength in the pre-/postcentral gyri and dorsolateral prefrontal cortex (DLPFC)/orbitofrontal cortex (OFC) in the motor sensory network and prefrontal cortex network, respectively; and increased FC strength in the anterior cingulate cortex/insula, ventrolateral prefrontal cortex (VLPFC)/OFC and DLPFC/VLPFC in the core network and prefrontal cortex network, respectively. These findings indicate that there are FC alterations among the brain regions implicated in eating as well as rewarding, even during the resting state, which may provide further evidence supporting the use of PWS as a model to study obesity and to provide information on potential neural targets for the medical treatment of overeating.

From passive overeating to "food addiction": a spectrum of compulsion and severity

A psychobiological dimension of eating behaviour is proposed, which is anchored at the low end by energy intake that is relatively well matched to energy output and is reflected by a stable body mass index (BMI) in the healthy range. Further along the continuum are increasing degrees of overeating (and BMI) characterized by more severe and more compulsive ingestive behaviours. In light of the many similarities between chronic binge eating and drug abuse, several authorities have adopted the perspective that an apparent dependence on highly palatable food-accompanied by emotional and social distress-can be best conceptualized as an addiction disorder. Therefore, this review also considers the overlapping symptoms and characteristics of binge eating disorder (BED) and models of food addiction, both in preclinical animal studies and in human research. It also presents this work in the context of the modern and "toxic" food environment and therein the ubiquitous triggers for over-consumption. We complete the review by providing evidence that what we have come to call "food addiction" may simply be a more acute and pathologically dense form of BED.

The neurobiological underpinnings of obesity and binge eating: a rationale for adopting the food addiction model

The food addiction model of overeating has been proposed to help explain the widespread advancement of obesity over the last 30 years. Parallels in neural substrates and neurochemistry, as well as corresponding motivational and behavioral traits, are increasingly coming to light; however, there are still key differences between the two disorders that must be acknowledged. We critically examine these common and divergent characteristics using the theoretical framework of prominent drug addiction models, investigating the neurobiological underpinnings of both behaviors in an attempt to justify whether classification of obesity and binge eating as an addictive disorder is merited.

Secretive food concocting in binge eating: test of a famine hypothesis

OBJECTIVE

Food concocting, or making strange food mixtures, is well documented in the famine and experimental semistarvation literature and appears anecdotally in rare descriptions of eating disorder (ED) patients but has never been scientifically investigated. Here we do so in the context of binge-eating using a "famine hypothesis of concocting."

METHOD

A sample of 552 adults varying in binge eating and dieting traits completed a Concocting Survey created for this study. Exploratory ED groups were created to obtain predictions as to the nature of concocting in clinical populations.

RESULTS

Binge eating predicted the 24.6% of participants who reported having ever concocted but dietary restraint, independently, even after controlling for binge eating, predicted its frequency and salience. Craving was the main motive. Emotions while concocting mirrored classic high-arousal symptoms associated with drug use; while eating the concoctions were associated with intensely negative/self-deprecating emotions. Concocting prevalence and salience was greater in the anorexia > bulimia > BED > no ED groups, consistent with their respectively incrementing dieting scores.

DISCUSSION

Concocting distinguishes binge eating from other overeating and, consistent with the famine hypothesis, is accounted for by dietary restraint. Unlike its adaptive function in famine, concocting could worsen binge-eating disorders by increasing negative effect, shame, and secrecy. Its assessment in these disorders may prove therapeutically valuable.

Fructose: it's "alcohol without the buzz"

What do the Atkins Diet and the traditional Japanese diet have in common? The Atkins Diet is low in carbohydrate and usually high in fat; the Japanese diet is high in carbohydrate and usually low in fat. Yet both work to promote weight loss. One commonality of both diets is that they both eliminate the monosaccharide fructose. Sucrose (table sugar) and its synthetic sister high fructose corn syrup consist of 2 molecules, glucose and fructose. Glucose is the molecule that when polymerized forms starch, which has a high glycemic index, generates an insulin response, and is not particularly sweet. Fructose is found in fruit, does not generate an insulin response, and is very sweet. Fructose consumption has increased worldwide, paralleling the obesity and chronic metabolic disease pandemic. Sugar (i.e., fructose-containing mixtures) has been vilified by nutritionists for ages as a source of "empty calories," no different from any other empty calorie. However, fructose is unlike glucose. In the hypercaloric glycogen-replete state, intermediary metabolites from fructose metabolism overwhelm hepatic mitochondrial capacity, which promotes de novo lipogenesis and leads to hepatic insulin resistance, which drives chronic metabolic disease. Fructose also promotes reactive oxygen species formation, which leads to cellular dysfunction and aging, and promotes changes in the brain's reward system, which drives excessive consumption. Thus, fructose can exert detrimental health effects beyond its calories and in ways that mimic those of ethanol, its metabolic cousin. Indeed, the only distinction is that because fructose is not metabolized in the central nervous system, it does not exert the acute neuronal depression experienced by those imbibing ethanol. These metabolic and hedonic analogies argue that fructose should be thought of as "alcohol without the buzz."

Dopamine Genetics and Function in Food and Substance Abuse

Having entered the genomics era with confidence in the future of medicine, including psychiatry, identifying the role of DNA and polymorphic associations with brain reward circuitry has led to a new understanding of all addictive behaviors. It is noteworthy that this strategy may provide treatment for the millions who are the victims of "Reward Deficiency Syndrome" (RDS) a genetic disorder of brain reward circuitry. This article will focus on drugs and food being mutuality addictive, and the role of dopamine genetics and function in addictions, including the interaction of the dopamine transporter, and sodium food. We will briefly review our concept that concerns the genetic antecedents of multiple-addictions (RDS). Studies have also shown that evaluating a panel of established reward genes and polymorphisms enables the stratification of genetic risk to RDS. The panel is called the "Genetic Addiction Risk Score (GARS)", and is a tool for the diagnosis of a genetic predisposition for RDS. The use of this test, as pointed out by others, would benefit the medical community by identifying at risk individuals at a very early age. We encourage, in depth work in both animal and human models of addiction. We encourage further exploration of the neurogenetic correlates of the commonalities between food and drug addiction and endorse forward thinking hypotheses like "The Salted Food Addiction Hypothesis".

Is food addiction a valid and useful concept?

In this paper, we consider the concept of food addiction from a clinical and neuroscientific perspective. Food addiction has an established and growing currency in the context of models of overeating and obesity, and its acceptance shapes debate and research. However, we argue that the evidence for its existence in humans is actually rather limited and, in addition, there are fundamental theoretical difficulties that require consideration. We therefore review food addiction as a phenotypic description, one that is based on overlap between certain eating behaviours and substance dependence. To begin, we consider limitations in the general application of this concept to obesity. We share the widely held view that such a broad perspective is not sustainable and consider a more focused view: that it underlies particular eating patterns, notably binge eating. However, even with this more specific focus, there are still problems. Validation of food addiction at the neurobiological level is absolutely critical, but there are inconsistencies in the evidence from humans suggesting that caution should be exercised in accepting food addiction as a valid concept. We argue the current evidence is preliminary and suggest directions for future work that may provide more useful tests of the concept.

Role of orexin-1 receptor mechanisms on compulsive food consumption in a model of binge eating in female rats

Orexins (OX) and their receptors (OXR) modulate feeding, arousal, stress, and drug abuse. Neural systems that motivate and reinforce drug abuse may also underlie compulsive food seeking and intake. Therefore, the effects of GSK1059865 (5-bromo-N-[(2S,5S)-1-(3-fluoro-2-methoxybenzoyl)-5-methylpiperidin-2-yl]methyl-pyridin-2-amine), a selective OX(1)R antagonist, JNJ-10397049 (N-(2,4-dibromophenyl)-N'-[(4S,5S)-2,2-dimethyl-4-phenyl-1,3-dioxan-5-yl]urea), a selective OX(2)R antagonist, and SB-649868 (N-[((2S)-1-{[5-(4-fluorophenyl)-2-methyl-1,3-thiazol-4-yl]carbonyl}-2-piperidinyl)methyl]-1-benzofuran-4-carboxamide), a dual OX(1)/OX(2)R antagonist were evaluated in a binge eating (BE) model in female rats. BE of highly palatable food (HPF) was evoked by three cycles of food restriction followed by stress, elicited by exposing rats to HPF, but preventing them from having access to it for 15 min. Pharmacokinetic assessments of all compounds were obtained under the same experimental conditions used for the behavioral experiments. Topiramate was used as the reference compound as it selectively blocks BE in rats and humans. Dose-related thresholds for sleep-inducing effects of the OXR antagonists were measured using polysomnography in parallel experiments. SB-649868 and GSK1059865, but not JNJ-10397049, selectively reduced BE for HPF without affecting standard food pellet intake, at doses that did not induce sleep. These results indicate, for the first time, a major role of OX(1)R mechanisms in BE, suggesting that selective antagonism at OX(1)R could represent a novel pharmacological treatment for BE and possibly other eating disorders with a compulsive component.

Putting desire on a budget: dopamine and energy expenditure, reconciling reward and resources

Accumulating evidence indicates integration of dopamine function with metabolic signals, highlighting a potential role for dopamine in energy balance, frequently construed as modulating reward in response to homeostatic state. Though its precise role remains controversial, the reward perspective of dopamine has dominated investigation of motivational disorders, including obesity. In the hypothesis outlined here, we suggest instead that the primary role of dopamine in behavior is to modulate activity to adapt behavioral energy expenditure to the prevailing environmental energy conditions, with the role of dopamine in reward and motivated behaviors derived from its primary role in energy balance. Dopamine has long been known to modulate activity, exemplified by psychostimulants that act via dopamine. More recently, there has been nascent investigation into the role of dopamine in modulating voluntary activity, with some investigators suggesting that dopamine may serve as a final common pathway that couples energy sensing to regulated voluntary energy expenditure. We suggest that interposed between input from both the internal and external world, dopamine modulates behavioral energy expenditure along two axes: a conserve-expend axis that regulates generalized activity and an explore-exploit axes that regulates the degree to which reward value biases the distribution of activity. In this view, increased dopamine does not promote consumption of tasty food. Instead increased dopamine promotes energy expenditure and exploration while decreased dopamine favors energy conservation and exploitation. This hypothesis provides a mechanistic interpretation to an apparent paradox: the well-established role of dopamine in food seeking and the findings that low dopaminergic functions are associated with obesity. Our hypothesis provides an alternative perspective on the role of dopamine in obesity and reinterprets the "reward deficiency hypothesis" as a perceived energy deficit. We propose that dopamine, by facilitating energy expenditure, should be protective against obesity. We suggest the apparent failure of this protective mechanism in Western societies with high prevalence of obesity arises as a consequence of sedentary lifestyles that thwart energy expenditure.