SCIENCE

Research shows people tend to overeat ultraprocessed foods, potentially explaining their link to weight gain and obesity, but the reasons why remain unclear.

By Aniket Chakraborty

Mar 13, 2025

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Former FDA commissioner Dr. Robert Califf suggested ultraprocessed foods may be addictive, acting on the same brain pathways involved in drug addiction.

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A new study from the National Institutes of Health examined how brains respond to ultraprocessed milkshakes, finding no average statistical difference in dopamine levels before and after consumption.

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"Responders" who did show small dopamine increases rated the shakes as more pleasant, wanted more, and ate nearly twice as many cookies at a later buffet compared to other participants.

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PET scans used in the study may not detect small dopamine changes well, meaning milkshakes likely did elicit responses that weren't measurable.

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Some addictive substances like nicotine or opioids trigger smaller dopamine responses that aren't always detectable, unlike cocaine which causes dramatic surges.

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Researchers are divided on whether to label ultraprocessed foods as "addictive," with some noting our attraction to calorie-dense foods evolved for survival.

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Ultraprocessed foods may stimulate the brain's reward system in an amplified way with enticing flavors and high levels of rapidly absorbed fat and sugar.

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Beyond brain studies, researchers also use behavioral criteria to assess addiction, with a 2021 review finding 14% of people met criteria for food addiction.

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Some researchers argue we should believe people when they say they're addicted to ultraprocessed foods, noting that "people want to stop, but they can't."

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