They suggest labelling ultra-processed foods (UPFs) as "addictive" might help some modify their behaviour.

It's estimated one in seven adults and one in eight children could be hooked on UPFs and people who consume foods that are high in fat and carbohydrates could "meet the criteria for diagnosis of substance use disorder".

Behaviours which could meet such criteria include intense cravings, symptoms of withdrawal, less control over intake, and continued use despite such consequences as obesity, binge eating disorder, poorer physical and mental health, and lower quality of life, the scientists said.

A team of international researchers reviewed 281 studies from 36 different countries, finding "ultra-processed food addiction" is estimated to occur in 14% of adults and 12% of children.

They said if some foods high in carbohydrates and fats are viewed as "addictive" it could potentially improve health through changes to social, clinical and political policies.

"There is converging and consistent support for the validity and clinical relevance of food addiction," said Ashley Gearhardt, the article's corresponding author and a psychology professor at the University of Michigan in the US.

"By acknowledging that certain types of processed foods have the properties of addictive substances, we may be able to help improve global health."

The authors of the paper, published in The BMJ, gave the example of a portion of salmon and a chocolate bar - the salmon has a carbohydrate-to-fat ratio of roughly 0-to-1. But the chocolate bar has a carbohydrate-to-fat ratio of 1-to-1, which appears to increase a food's addictive potential, they said.

"Many ultra-processed foods have higher levels of both. That combination has a different effect on the brain," said co-author Professor Alexandra DiFeliceantonio, assistant professor at the Fralin Biomedical Research Institute in the US.

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'Addictive potential'

The researchers, from the US, Brazil and Spain, said: "Refined carbohydrates or fats evoke similar levels of extracellular dopamine in the brain striatum to those seen with addictive substances such as nicotine and alcohol.

"Based on these behavioural and biological parallels, foods that deliver high levels of refined carbohydrates or added fats are a strong candidate for an addictive substance."

The speed at which these foods deliver carbohydrates and fats to the gut could also play a role in their "addictive potential", the authors added.

Food additives may also contribute to the "addictiveness of UPFs", they said. While these additives, added to food for taste and to "improve the mouth feel" are unlikely to be addictive on their own, they could "become powerful reinforcers of the effects of calories in the gut", they wrote.

Not all foods have addictive potential

However, the academics stress not all foods have addictive potential.

They conclude: "While further careful research is needed to determine the exact mechanism by which these foods trigger addictive responses, UPFs high in refined carbohydrates and fats are clearly consumed in addictive patterns and are leading to deleterious health outcomes."

They added: "Understanding of these foods as addictive could lead to novel approaches in the realm of social justice, clinical care, and policy approaches."