Updated Mar 13, 2024 - Health

Your brain on junk food: New research shows it's not just harming your body

Illustration of a honey bun pastry shaped like a brain sitting on paper shaped like a head

Illustration: Natalie Peeples/Axios

We know how ultra-processed foods like chips and sugary cereals affect our bodies. New research is digging into how junk food hits our brains.

Why it matters: Beyond elevating risk of obesity, diabetes and heart disease, heavily processed foods can harm mental health, mess with sleep — and even be addictive like alcohol or nicotine.

  • Some scientists are proposing a new mental health condition — "ultra-processed food use disorder," The Wall Street Journal reports.

State of play: People who consistently eat high-fat, high-sugar snacks demonstrate higher activity in the parts of their brains that create dopamine, according to a study published in Cell Metabolism.

  • In just eight weeks, participants' brains started to reward them for indulging in junk food. Their desire for low-fat foods started to disappear.

Researchers have discovered other troubling effects:

  • In one study, some participants were given sugary, processed breakfasts to start their day. Others were given a healthier meal.
  • Those who had junk food for breakfast didn't perform as well on learning and memory tests.

Zoom in: One way an imbalanced diet affects our brains is through the gut, The Journal notes.

  • A junk-food forward diet is likely to result in a gut microbiome that is less diverse and has fewer types of bacteria, which work together to boost the immune function and regulate stress.
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