We’re becoming more obese, as a society. Is this because some of us are becoming addicted to certain foods? One study, at Connecticut College in 2013, suggested that Oreos were “as addictive as cocaine,” and certainly, some people who are overweight exhibit behaviours associated with addiction, such as an inability to avoid particular foods and a tendency to over-consumption at times of stress. But this is not true of all overweight individuals. So does ‘food addiction’ actually exist?
To answer that, we first need to understand what addiction is. The criteria for diagnosing substance addiction disorders in the Diagnostic And Statistical Manual Of Mental Disorders include developing a tolerance, having withdrawal symptoms and becoming dependent. The latest version, DSM-5, added: “craving or a strong desire or urge to use a substance”.
The involvement of the brain is key to diagnosing addiction. Addiction affects areas of the brain that are linked to pleasure, reward and decision-making. It also affects neurotransmitters, the chemical signals used for communication between brain cells and brain regions. Over time, memory of previous exposures to rewards (eg: food, sex, alcohol or drugs) leads to a biological response, such as cravings.
The best tool that researchers have for applying all this to food is the Yale Food Addiction Scale (YFAS). This 25-point questionnaire was developed in 2009 by Ashley Gearhardt, an assistant professor of clinical psychology at the University of Michigan. She believes addictive processes do play a role in eating-related problems.
“My research asks, how can we identify that group of people who are most likely to be showing an addictive response to food? To do that, I developed the Yale Food Addiction Scale. We’re not using body weight to identify people who could be addictive eaters; instead, we’re using the same criteria we’d use for any addiction. This gives us a starting point, so we can look at whether there are behavioural, cognitive or biological markers in this group.”
In one experiment, Gearhardt showed people pictures of ‘treats’ such as chocolate milkshakes, then gave them the real thing. She found that people who have more ‘addictive-like’ eating behaviour have more activity in brain regions linked to reward and desire when exposed to ‘addictive cues’ – the pictures of treats – than when they saw other images. They also have less of an inhibitory response in their brains once they have drunk the chocolate milkshake than after consuming other non-addictive foods.
“This indicates that this group of people is very reactive to cues in the environment that suggest these foods are available,” explains Gearhardt. “Then, when they start consuming, the circuitry in the brain that usually allows us to apply the brakes and stop eating may not be working as well.”
This same pattern is also seen in people with ‘conventional’ addictions. According to Gearhardt, this further strengthens the case for food addiction. In another study, Gearhardt’s team recruited 500 people and asked them to complete the YFAS and to indicate which foods they were thinking of while reading particular statements. The usual suspects were at the top of the list: ice cream, chocolate, biscuits and sweets. According to Gearhardt, these are foods our brains have not really evolved to handle yet.
Eating too much of the wrong thing
Our modern diets contain far more processed, sugar-heavy food than in previous generations, and it’s showing on our waistlines. NHS figures show the proportion of obese adults rose between 1993 and 2013, from 58 to 67 per cent in men and from 49 to 57 per cent in women. This is set to rise even further, predicts the World Health Organization, to a whopping 74 per cent of men and 64 per cent of women in the UK by 2030.
However, food addiction studies have generally been conducted on animals, or snapshot studies in humans. And despite one support group for overeaters having 6,000 members in six countries, including the UK, there still haven’t been any comprehensive scientific reviews to study the issue. This is a problem that Dr Hisham Ziauddeen, a senior researcher in food reward processing at the University of Cambridge, feels undermines the idea of food addiction as a medical condition.
“The evidence for thinking food might be addictive, or that food addiction exists, is actually fairly weak,” he says. “I wouldn’t say it definitely does not exist – it’s quite possible, given the breadth of symptoms that people with eating disorders describe, that a small group of people have problems with disordered eating that look very much like an addiction, and share the kinds of things that people with alcohol and drug addictions feel and experience.”
But he remains unconvinced that the Yale Food Addiction Scale could identify these people, or convince ‘doubters’ like him. “People who score very highly on the scale also score very highly for some of the more conventional eating disorders. So the scale is measuring certain behaviours that we see with other eating disorders – but it’s not actually capturing something distinct,” he argues.
Some researchers go further, and say food addiction is a potentially dangerous public health message. Ian Macdonald, a professor of metabolic physiology at the University of Nottingham, feels this could be because it’s difficult to reconcile an addiction with something that is essential to human life. Things like alcohol and drugs are, essentially, choices – eating is not.
“I don’t think the term ‘food addiction’ is particularly helpful, and I certainly don’t think using the word ‘addiction’ in combination with specific nutrients like fat and sugars, or foods like chocolate, should be encouraged,” Macdonald says. “Everyone must eat to survive, so an addiction has to be something much more extreme than normal eating. It is not helpful to encourage the public to use these terms, because they will understandably expect it is similar to addictions to heroin, nicotine or alcohol, which is not true.”
Even as a clinician, Macdonald says he is reluctant to use the term ‘food addiction’. “I don’t think health professionals should use the term unless they make it very clear exactly what they are talking about. The term ‘eating addiction’ is now being recognised in psychological circles as being helpful in describing altered behaviour and cravings for specific types of food, or food in general. However, even this can be used inappropriately and over-interpreted.”
It’s possible to see how the concept of addiction might be counterproductive. Labelling ‘food addiction’ as a disease may create or reinforce a perception that excessive eating is something we are powerless to resist. If someone told you chocolate was addictive, or you were hard-wired to get hooked on junk food, would this strengthen or weaken your New Year’s resolutions to eat healthily?
Prof Peter Rogers, who studies nutrition, behaviour and the brain’s control of appetite at the University of Bristol, says labelling food addiction as a condition could have unpredictable effects. “A label like ‘food addiction’ is not trivial; it can have an effect that directly influences our experience of eating, of feeling hungry and wanting to eat.”
His research, published in the journal Appetite, looked at how giving information about food addiction affects people’s behaviour and preferences. In the study, 60 volunteers read different ‘news stories’ claiming scientists had either proven or disproven the existence of food addiction, before taking a taste test of healthy and unhealthy foods.
“Among people who had just read that food addiction was real there was an interesting split,” Rogers explains. “Some people ate a lot, some people very little indeed. Which fits the theory that some people, having read the passage, thought ‘I can’t help myself’ and succumbed, while others thought ‘these foods are addictive’ and refrained. So one implication is that the more people read about food addiction, the more they have a particular mindset when they are confronted with certain kinds of foods – and that can be helpful or unhelpful.”
This may hint towards possible treatments for problem overeating. Having a concept of certain ‘problem foods’ that cause people to overeat and that should be avoided, could be used in a similar way to the complete abstinence model used to manage conventional addictions.
Before deciding on possible treatments, though, there needs to be a consensus as to whether food addiction actually exists, and if so, how it functions. As yet, the experts are far from agreed on these points. Clearly, certain people do crave certain foods, but we don’t fully understand what drives these cravings, or what reward people get from eating the foods they crave. There’s still plenty to chew over.
This is an edited extract from Are cookies as addictive as cocaine? from issue 291 of BBC Focus magazine – make sure you don’t miss out on the full article every issue and subscribe here.