A Small Daily ‘Dose’ Of Sugar And Fat Can Make Your Brain Crave More

If you’ve ever bought a box of donuts only to find it triggers a donut phase in your life, you may appreciate the findings of a new study. The research, led by a team at the Max Planck Institute for Metabolism Research and Yale University, finds that just a small daily addition of fat and sugar to the diet can trigger changes in taste preferences and to the brain pathways that underlie reward. The study was published in Cell Metabolism. Whether the changes are reversible and how long it would take to reverse them are up for grabs.

To test whether a small shift in nutrient intake can have measurable effects, the research team gave one group of people a high-fat, high-sugar yogurt to add to their regular diets every day for eight weeks. Another group got a low-fat, low-sugar version of the yogurt for the same period of time.

At the end of the eight weeks, the participants rated their preferences for food and drinks of various fat and sugar levels – those who had consumed the high-fat/high-sugar snack for eight weeks rated the lower fat options as less likable. This wasn’t the case for the low-fat/low-sugar group.

And when the participants were given milkshakes to consume during an MRI scan, the brains of the high-fat/high-sugar snackers showed some differences. They had increased activity in parts of the brain that govern motivation and reward and rely on dopamine – the same systems that are active in response to drugs. Previous research has found similar changes in both animals and humans.

“[L]ike addictive drugs,” the authors write in their paper, “there is evidence for a causal role of diet (i.e., fat/sugar) in rewiring brain circuits to promote further seeking of energy-dense foods.”

Although the participants in the current study didn’t gain weight, it’s possible they would have over a longer time period, or with larger shifts in diet. The real takeaway is how small a dietary change can lead to alterations in the brain and in taste preferences, likely below the level of conscious perception.

“Our measurements of brain activity showed that the brain rewires itself through the consumption of chips and co,” said study author Marc Tittgemeyer in a press release. “It subconsciously learns to prefer rewarding food.”

The findings have some limitations – the study was small (57 participants) and included only those who had initially rated the snacks as appealing. It might be that people who didn’t find the snacks likable would have reacted differently.

Still, the findings highlight how our environments can contribute to our preferences and behavior. Being surrounded by junk food or lacking access to healthy food could have significant effects on taste preferences and brain “wiring,” particularly over the long term. And it’s unclear how reversible the changes are.

“New connections are made in the brain, and they don’t dissolve so quickly,” said Tittgemeyer. “After all, the whole point of learning is that once you learn something, you don’t forget it so quickly.”