Are Ultraprocessed Foods Addictive?

Over the last decade or so, research has revealed a clear pattern: People tend to overeat ultraprocessed foods. This could be one reason they’re linked with weight gain and obesity.

What isn’t clear is why we are so prone to overeating them.

Dr. Robert Califf, the former commissioner of the Food and Drug Administration, offered one hypothesis at a Senate hearing in December: “These foods are probably addictive,” he said, adding that they may act on the same brain pathways involved with addiction to opioids and other drugs.

As recently as eight years ago, such a concept was highly controversial, said Ashley Gearhardt, an addiction researcher at the University of Michigan. She described being heckled onstage at a scientific conference in 2017 for suggesting that some ultraprocessed foods may act as addictive substances. Now, she said, more researchers have started coming around to the idea.

But a major question remains: How do you prove it?

A study published Tuesday, the largest of its kind, took a big swing at this conundrum. But its results raised more questions than answers. Here’s what we know — and don’t know — so far.

Can food give you a druglike dopamine hit?

One way researchers study addiction is by looking at the brain levels of the neurotransmitter dopamine — a natural signal that helps you learn to seek what you need to survive. When you eat, your brain releases the chemical, said Dana Small, a cognitive neuroscientist at McGill University in Montreal. If it’s a food you know and like, she said, just thinking about or seeing it can trigger an increase in dopamine, reminding you that it’s a good source of fuel and nudging you to eat more.

Addictive drugs co-opt this survival system by triggering a larger surge in dopamine and driving people to use them again and again, Dr. Small said.