What happens in early life may not stay in early life, at least when it comes to diet and the brain.
A new study published in Nature Communications found that mice exposed to a high-fat, high-sugar diet early in life showed lasting changes in feeding behavior as adults.
In the study, young mice were given a high-fat, high-sugar diet during a key developmental window. Later, their diet was normalized and their body weight stabilized. Even so, researchers found persistent differences in how the animals regulated food intake compared with mice that had eaten a standard diet from the start.
Those differences were linked to changes in the hypothalamus, a region of the brain that helps control hunger, fullness and energy balance.
“Our findings show that what we eat early in life really matters,” said Dr. Cristina Cuesta-Martí, first author of the study. “Early dietary exposure may leave hidden, long-term effects on feeding behaviour that are not immediately visible through weight alone.”
In other words, body weight alone did not tell the whole story. Even when adult weight looked similar between groups, feeding patterns and underlying brain signaling differed.
The researchers also explored whether targeting the gut microbiome could influence those long-term effects. They tested a specific probiotic strain, Bifidobacterium longum APC1472, as well as a combination of prebiotic fibers commonly found in foods such as onions, garlic and asparagus.
“Crucially, our findings show that targeting the gut microbiota can mitigate the long-term effects of an unhealthy early-life diet on later feeding behaviour,” said Dr. Harriet Schellekens, lead investigator of the study. “Supporting the gut microbiota from birth helps maintain healthier food-related behaviours into later life.”
Both approaches were associated with improvements in feeding behavior in the mice that had been exposed to early high-fat diets. The probiotic strain appeared to act in a more targeted way, while the prebiotic fibers led to broader changes in the gut microbiome.
This was an animal study, and the findings do not prove that early high-fat or high-sugar diets cause permanent appetite changes in children. Still, the research adds to growing evidence that early developmental periods may be especially important for shaping long-term patterns of eating and metabolism.
As scientists continue to study the gut-brain connection, questions remain about how these findings translate to humans and whether specific microbiome interventions can meaningfully influence lifelong eating behavior. For now, the study offers insight into how timing, not just total calories, may influence how the brain regulates appetite over time.
This study was funded by Research Ireland, a Government of Ireland Postgraduate Scholarship and a research award from the Biostime Institute for Nutrition & Care.