Australasian Science: Australia's authority on science since 1938

Is Food Addiction Real?

food addict

There is mounting evidence that areas of the brain associated with reward are activated by food stimuli in similar ways to other forms of addiction.

By Tracy Burrows

Emerging research suggests that food addiction may be a previously unrecognised factor contributing to the rise in overweight and obesity.

The prevalence of obesity is increasing rapidly worldwide, with 35% of Australian adults classified as overweight and 12% classified as obese in 2008. Obesity increases the risk for a variety of lifestyle diseases, including cardiovascular disease, hypertension, diabetes and some cancers, as well as reducing quality of life.

Weight gain and obesity develop when energy intake from food and beverages exceeds energy expenditure from physical activity and other metabolic processes. Accordingly, obesity treatment and prevention efforts have traditionally focused on two key factors: dietary intake and physical activity.

Previous research has consistently shown that causes of obesity are multifactorial and influenced by gender, genetic make-up, environment, place of residence, culture, socio­economic status and education level. However, even if these factors are adjusted for, many individuals who try to lose weight still fail to achieve success in weight loss and maintenance long-term. Could there be other factors that contribute to our understanding of the cause of obesity and offer effective potential long-term treatment opportunities?

One possible exploratory variable could be “food addiction”. The term is becoming popular in published literature and highly topical in the mainstream media. “Food addiction” does not currently have an accepted definition and is not a clinically diagnostic condition by either the World Health Organisation’s International Classification of Diseases or the American Psychiatric Association’s Diagnostic & Statistical Manual of Mental Disorders.

However, there is an increasing amount of literature exploring this possible phenomenon. Research suggests that similarities exist between other classic forms of addiction, such as alcohol and drug addiction, and food dependence. Behaviours including tolerance to large amounts of food, persistent craving for specific foods, and lack of control over the amount of food consumed are being used in conjunction with the term “food addiction”.

While there is a plethora of animal studies related to food addiction, there are relative few in the area of human food dependence and addiction. This scarcity is reflected in the extremely limited number of methods available to detect possible indicators of food addiction. To date, food addiction has been a largely self-identified and self-reported condition, which has limitations in regards to the reliability and validity of reporting.

One of the few tools available to assess traits and behaviours associated with potential food addiction is the Yale Food Addiction Scale, which takes the form of a questionnaire in which individuals self-report their post-food consumption emotional state, physical responses, attitudes towards foods and eating, and potential professional or social implications of addictive food behaviours. There are seven symptoms assessed, and a positive screening on three or more symptoms in an individual indicates that the individual has addictive behaviours towards certain types of food.

In our own 2013 cross-sectional study of young Australian adults (n=504), 94% of participants had at least one symptom and 6.2% exhibited three or more symptoms associated with food addiction. These figures confirm that addictive behaviour towards foods is an authentic phenomenon for a subset of adults, and this warrants further exploration by objective means.

The recent use of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), in the food and nutrition domain has allowed the study of neurological mechanisms behind chronic addictive behaviours towards food. fMRI is a technique that shows areas of the brain “lighting up” when they are active.

Our recent review of research using fMRI to analyse brain responses after seeing, eating or smelling food has shown that the current data are inconclusive about whether food addiction is a real phenomenon or not. However, there is mounting evidence that areas of the brain associated with reward are activated by food stimuli in similar ways to other forms of addiction in susceptible individuals.

Some forms of obesity may be linked to increased anticipation of reward from food cues and a decrease in reward during food consumption. This tendency could lead to overeating to compensate for imbalances in the neural reward pathways and a subsequent diminished experience of reward. Individuals may be more susceptible to behaviours related to possible food addiction as a result of some form of neural disruption. In addition to being the most complex organ in the human body, the brain is a very metabolically active organ that utilises a large proportion of the body’s energy itself but also plays a key role in maintaining many bodily processes in which many foods and nutrients are linked.

Objective instruments like fMRI suggest that an addiction to food may be measurable. Research studies to date indicate that food addiction could potentially involve aberrations in an individual’s neural circuitry similar to other addictive disorders.

Most research into the possibility of food addiction use foods that are high in fat, sugar and salt, including potato chips, chocolate, milkshakes, pizza and hamburgers. These are referred to as “extras” or “discretionary foods” in the Australian Guide to Healthy Eating, and are commonly consumed in excess by the general population, contributing up to 40% of daily energy intakes in some individuals.

The choice of these discretionary foods as a focus in food addiction research appears somewhat arbitrary. They also predominate the topic in mainstream media discussion about food addiction and are the foods popularly deemed to be the most likely to be “highly addictive”. However, anecdotal evidence indicates that perceived “healthier” foods, such as fruit, vegetables and cheese, may also be linked with addictive behaviours.

Research efforts are currently directed towards the development of a widely endorsed definition of food addiction, the refinement and validation of objective diagnostic tools, and investigations to examine direct relationships between behaviours and traits possibly associated with addiction. Intervention studies for other forms of addiction will also provide valuable insights into future treatment opportunities for people exhibiting addictive behaviours towards food.

At this point in time, food addiction remains a contentious theoretical construct. However, research and evidence in this area is building at an exponential rate. Results from studies to date suggest that food addiction could be a missing link in understanding the current rates of obesity and in developing effective weight loss and weight maintenance interventions for the future.

Dr Tracy Burrows is a Senior Lecturer at the University of Newcastle.