Food addiction – What is the evidence?

The term food addiction has been in use for a number of decades. Following publication of a number of papers that focused on food addiction with particular regard to sugar, fat and processed foods, there has been extensive publicity in the press on the supposition that certain foods are ‘addictive’ and that food ‘addiction’ is contributing to the current obesity epidemic. Despite this media exposure, there is a certain degree of confusion around the term ‘food addiction’, its diagnosis, definition and whether it even exists. Associate Professor Graham Finlayson (University of Leeds) explored the scientific validity and measurement of food addiction in humans and discussed its contribution to overeating or as a subtype of obesity. More recently, the term addiction is being used colloquially to describe anything done to excess (e.g. addictions to gambling, Internet, sex and food). A key task for researchers in this area is to discern which addictions are ‘real’. Classifications of clinically defined psychiatric conditions for which there are agreed diagnostic procedures are incorporated into the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association (APA). In previous versions, there were no mentions of ‘addiction’; instead the term ‘SubstanceRelated Disorders’ was used. In the latest version, published in 2013, this definition has been extended to cover ‘Substance-Related and Addictive Disorders’. In early 2013, prior to publication, the APA’s Classification Committee rejected ‘food addiction’ as a diagnosable entity in the fifth edition of DSM (DSM-V), published in late 2013. This decision should signal caution and add to the considerable doubt about the authenticity of food addiction as a recognisable condition. The question of whether food addiction is a valid scientific concept is not new but its reexamination has been stimulated by recent methodological and scientific developments. It has been claimed that findings from rodent studies show similarities between the behavioural patterns elicited by foods and drugs, as well as correspondence between the effects of food and (hard) drugs on brain neurotransmitters. But the concept of food as a ‘drug’ is controversial, as will be discussed later in this report. Another reason for the returning interest in food addiction is the development of ‘The Yale Food Addiction Scale’ (YFAS), described as ‘a measure that has been developed to identify those who are most likely to be exhibiting markers of substance dependence with the consumption of high fat/high sugar foods’ (Gearhardt et al. 2009). Psychometric scales, such as the YFAS, can capture individual differences in susceptibility to overeating. Although this approach holds promise for the investigation of hedonic responses (i.e. pleasure/reward systems) to the sensory features of food and the specific eating behaviours that characterise susceptible individuals at risk of weight gain, these characteristics should not be regarded as being markers of addiction. Moreover, there are problems when using this type of assessment in research. It assumes that addiction is stable, quantifiable and measurable; provides no clear threshold to differentiate between addictive and normative eating behaviours; and overlaps with other scales (e.g. the scale used to assess the severity of emotional eating). Correspondence: Sarah Coe, Assistant Nutrition Scientist, British Nutrition Foundation, Imperial House, 15–19 Kingsway, London, WC2B 6UN, UK. E-mail: s.coe@nutrition.org.uk bs_bs_banner