Neurobiologic basis of craving for carbohydrates

doi:10.1016/j.nut.2013.06.010

Nutrition

Volume 30, Issue 3, March 2014, Pages 252-256

https://doi.org/10.1016/j.nut.2013.06.010 Get rights and content

Abstract

Objectives

There is a relationship between emotional disorders, obesity, and craving for carbohydrates. This relationship complicates the success of treatments aimed at combatting obesity, which is considered to be the epidemic of the twenty-first century. We conducted a review of the neurobiologic basis for carbohydrate craving, with the hope that this understanding will enable the design of more efficient therapeutic strategies.

Method

We conducted a non-systematic literature search in PubMed using MeSH.

Results

Research on the basis of carbohydrate craving is varied, but may be grouped into five main areas: the serotonergic system, palatability and hedonic response, the motivational system, stress response systems, and gene–environment interaction.

Conclusions

The models that integrate motivational systems with palatability and hedonic response studies are the ones that we believe can best explain both craving for carbohydrates and related addictive phenomena. Research has contributed to a greater understanding of the neurobiologic basis of carbohydrate craving. The latter, in turn, contributes to an understanding of the implications, challenges, and possible therapies that might be put in place to cope with this phenomenon.

Introduction

The growing global obesity epidemic and its associated pathologies [1] have focused research on the variables associated with overeating and the barriers to achieving changes in nutritional habits [2]. Research has ranged from social and cultural variables, such as the availability of food or the effects of advertising in childhood [2], [3], to attempts at elucidating the mechanisms associated with the tendency toward excessive consumption of fats and carbohydrates. Such research also has suggested the possibility that there may be an addictive pattern to the consumption of these nutrients under certain circumstances [4], [5], [6].

We know that emotional factors have become increasingly important based on associations found among obesity, anxiety, and mood disorders [5]. Carbohydrates are exceptionally involved in these associations, which has led to further research into their patterns and roles. Sugar addiction, carbohydrate craving, and emotional eating have been correlated with obesity and being overweight. This has led to the establishment of a strong correlation between obesity, anxiety, and mood disorders [4], [5], [6], [7], [8], [9], [10], all of which have important public health implications.

The scientific literature supports the existence of carbohydrate-craving syndrome, in which carbohydrate intake medicates a dysphoric mood state [8]. This syndrome is defined as a food and mood disorder, characterized by an irresistible urge to consume sweets or starchy foods in response to negative moods [9]. The criteria listed in Table 1 have been proposed to operationalize this phenomenon [8]. Carbohydrate intake appears to temporarily improve mood in carbohydrate cravers, whereas individuals who have no craving for carbohydrates usually complain of fatigue after eating these foods [9], thus revealing a different relationship with this nutrient.

However, despite the important role of these relationships, the underlying neurobiologic mechanisms remain unclear and have not been directly related to emotional factors. Understanding these phenomena potentially could be important for several reasons. On the one hand, this would allow public health specialists and clinicians to understand realistically the behavioral changes of individual patients and the general population, considering how our biology works. On the other hand, this knowledge would allow specific pharmacologic strategies to be developed that may lead to more successful outcomes when dealing with obesity and its consequences.

Given the importance of understanding the neurobiologic mechanisms underlying the phenomenon of carbohydrate craving, we aim to review the main neurobiologic hypotheses that explain carbohydrate craving, and link carbohydrate cravings with related phenomena, such as emotional eating and obesity, from a neurobiologic perspective.

Section snippets

Methods

A focused review of the available literature was conducted by using the database www.pubmed.org. The MeSH tool was used and the search matrix included the terms stress, carbohydrates, dietary carbohydrates, food, emotional eating, addictive behavior, and evolution. By combining these terms, 2187 articles were found, of which some studies were selected according to the objectives of this review.

Results

We found dispersed information from different lines of research on carbohydrate craving. We then categorized these findings into five groups that had similar research lines. The serotonergic hypothesis is presented first because it is the first hypothesis to emerge and the one that has received the most attention in the literature. The hypotheses that follow are presented in terms of the degree to which they focus on physical consumption variables, thus beginning with palatability and ending

Discussion

The results of this review, although only focused on carbohydrate craving, allow us to begin to understand the neurobiologic mechanisms that individuals and clinicians must overcome when attempting to achieve behavioral changes to address the obesity epidemic [1], [2].

The first group of studies, which focus on the role of the serotonergic pathways, link mood levels with a disposition to seek carbohydrates [11], [12]. These studies also imply a lapse in time between carbohydrate consumption and

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We describe a case of craving for menthol sweets in a 53-year-old woman with excessive consumption of menthol sweets (100 units/day). She was admitted with a history of rheumatoid arthritis, obesity, anxiety associated with onychophagia and pinching of the skin. Organic disorders were ruled out with paraclinical tests and in-hospital treatment was administered. At discharge, the patient's condition was stable, but because of exacerbated pain due to the rheumatological disease, she presented depressive symptoms, requiring her medication to be adjusted.
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For instance, Ansari et al. showed a positive correlation between depressive symptoms and unhealthy food consumption, including sweets, cookies, snacks, and fast food among college students [15]. Mood disorders can also lead to carbohydrate-craving and increases in sweet or starchy food intake [16,17]. In fact, meals with high-carbohydrate content can temporarily lift the mood, particularly because consumption of highly palatable food activates the brain opioid system, producing hedonic responses [16].
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ReviewNeurobiologic basis of craving for carbohydrates

Abstract

Objectives

Method

Results

Conclusions

Introduction

Section snippets

Methods

Results

Discussion

Appetite

Neurosci Biobehav Rev

Physiol Behav

Physiol Behav

Appetite

Eat Behav

Appetite

Am J Clin Nutr

Physiol Behav

Behav Brain Res

Am J Clin Nutr

Appetite

Pharmacol Biochem Behav

Appetite

Physiol Behav

Physiol Behav

Physiol Behav

Appetite

Review
Neurobiologic basis of craving for carbohydrates