In a study published in 2022 in the journal Appetite, researchers compared the consumption of ultra-processed food in 735 young Australian adults who had and did not have food addiction.

Researchers assessed foods as addictive according to the YFAS. They found that young adults who were food addicted ate more of their energy percentage (per cent) from ultra-processed foods. Those who did not identify as food addicted ate a lower energy percentage from ultra-processed foods.

The study authors added: “For each additional food addiction symptom reported, the per cent from ultra-processed foods was higher and  per cent from unprocessed foods was lower.”

A 2022 national poll conducted by researchers at the University of Michigan Institute for Healthcare Policy and Innovation found that 1 in 8, or about 13 per cent, of adults over the age of 50 displays signs of addiction to highly processed foods.

This was determined if the person had “two or more symptoms out of 11 plus significant impairment or distress.”

The authors noted that 44 per cent of the adults indicated at least one symptom of food addiction, the most common being intense cravings to processed foods. Notably, “older adults who rated their mental health as fair or poor were at least three times more likely to meet food addiction criteria compared with those reporting excellent, very good or good mental health.”

The researchers added: “Many people report eating highly processed foods not only for the calories they provide, but also to experience pleasure and cope with negative emotions.

“Cravings for highly processed foods can also be intense and challenging to resist, and people may experience withdrawal-like symptoms when they try to reduce the amount they consume.”

A Brazilian-based cross-sectional study that included around 6,000 people examined whether consuming ultra-processed food was associated with food addiction. (The YFAS was used to determine food addiction in participants.)

The results, which were based on self-reported questionnaires and published in the journal Appetite in 2023, found that “individuals with food addiction had lower consumption of fresh fruits, vegetables and beans. They also had higher consumption of ultra-processed foods: hamburgers/sausages, instant noodles, packaged snacks, and/or salty cookies, and sandwich cookies, sweets, and/or treats.”

In an article published in 2020 in Nutrients, Dr Robert H. Lustig wrote that the global pandemic of non-communicable diseases stems from markers of obesity and poor diet and argued that ultra-processed foods should be regulated in the same way other addictive substances are regulated.

This is because they fall under the same four criteria (abuse, toxicity, ubiquity and externalities) that are considered by the public health community as “necessary and sufficient” for regulation.

Of the addictive nature of ultra-processed foods, Lustig wrote: “Added sugar (and specifically the fructose moiety) is unique in activating reward circuitry; fructose works both directly and indirectly to increase consumption; and that both obesity and chronic fructose exposure down-regulate dopamine receptors, requiring greater and greater stimuli to enact a reward-signalling effect (tolerance), a primary component of addiction.”

In a systematic review published titled What Is the Evidence for Food Addiction? scientists assessed 52 studies and 32 articles on processed food and addiction.

Their research, which was published in the journal Nutrients in 2018, found that: “Overall, the majority of the studies in the present systematic review evaluated foods with added sweeteners (e.g. sugar, saccharine), and many experiments combined sweeteners with fats such as hydrogenated oils or lard.

“The current review found that the most common foods associated with addictive symptoms were those high in added fats and/or refined carbohydrates such as sugar.”

When given the choice between saccharin-sweetened water and cocaine, rats are more likely to choose the sweeteners, according to a 2018 study published in PLoS One. In the study, researchers tested rats that had never been fed refined sugars or sweeteners before. no prior experience with refined sugar or artificial sweeteners.

The authors stated: “Rats were allowed to choose mutually-exclusively between water sweetened with saccharin–an intense calorie-free sweetener – and intravenous cocaine – a highly addictive and harmful substance–the large majority of animals (94 per cent) preferred the sweet taste of saccharin.

“Importantly, each day before making their choices, rats were allowed to alternatively sample [the other option] learn their respective reward value.”

The researchers concluded: “Our findings clearly demonstrate that intense sweetness can surpass cocaine reward, even in drug-sensitized and -addicted individuals.”

In the late 1980s, major tobacco corporations like R.J. Reynolds and Philip Morris (now Altria) acquired and owned several Big Food brands, including Kraft, Nabisco and General Mills.

At this time, Big Tobacco began to change and reformulate these food products, using the same tactics in targeted marketing and formulation of their tobacco products, with an increase in colours, flavours and additives, to create more appealing and addictive processed foods. This also included food specifically marketed to children.

Although these tobacco companies have severed ties with food corporations, many of these processed food formulations remain.

A 2023 research report published in the journal Addiction found that: “Tobacco-owned foods were 29 per cent more likely to be classified as fat and sodium hyper-palatable food (HPF) and 80 per cent more likely to be classified as carbohydrate and sodium HPF than foods that were not tobacco-owned between 1988 and 2001.

“The availability of fat and sodium HPF and carbohydrate and sodium HPF was high in 2018 regardless of prior tobacco-ownership status, suggesting widespread saturation into the food system.”

In 1988, the Surgeon General concluded that cigarettes and other tobacco products are addictive by using three criteria: “(1) they trigger compulsive use, (2) they have psychoactive effects and (3) they are reinforcing,” writes Gearhardt in a 2022 analysis published in Addiction.

And since then, a fourth criterion was also added to addictive identification — the product’s ability to “trigger strong urges or craving”.

Using this same standard of criteria for tobacco products, Gearhardt argues that ultra-processed foods can be considered addictive.

And, “to identify the key addictive components in [highly processed foods], the same care and control employed in understanding the addictive potential of drugs needs to be applied to studies of [highly processed foods].”

Because food addiction has been controversial to define, Gearhardt, then a doctoral student at Yale University, created the YFAS in 2009 as a standardized tool to measure the signs of addictive eating behaviours.

The self-reported questionnaire uses questions based on criteria used for substance disorders in the Diagnostic and Statistical Manual of Mental Disorders.

It is meant to evaluate behaviour with questions similar to those that would ask about other substance abuse issues, including drugs and alcohol, regarding cravings, withdrawal symptoms and failed efforts to stop.

The scale has become a staple for food research around the world and has been translated into many languages. Gearhardt explained to the Guardian, “I took the standard diagnostic criteria for alcohol, nicotine, cocaine and heroin, and translated them to food.”

The YFAS is the basis for much of the research conducted on food addiction in the past 15 years.

• The Defender report