Summary: New research shows that exposure to the smell of fatty foods during pregnancy and early life can reprogram the developing brain and increase the risk of obesity and insulin resistance in adulthood. Even when mothers consumed a healthy low-fat diet, the presence of fatty food odors altered how offspring responded to high-fat foods later.
The changes were linked to long-term shifts in brain circuits that regulate hunger, reward, and metabolism. The findings suggest that prenatal and early sensory exposure to food cues may shape metabolic health independently of maternal weight.
Key Facts:
- Odor Exposure Effect: Fatty food smells during development increased obesity and insulin resistance in adulthood.
- Brain Circuit Changes: Reward and hunger-regulating neurons were permanently altered in offspring.
- Diet Independent: Effects occurred even when mothers ate a low-fat, healthy diet.
Source: Max Planck Institute
A research team at the Max Planck Institute for Metabolism Research has found that the smell of fatty foods during pregnancy increases the risk of overweight and obesity in children.
The researchers fed pregnant mice a healthy diet low in fat but containing fatty smells, such as the smell of bacon.
The mothers themselves did not change their metabolism, but their offspring reacted more strongly to a high-fat diet and developed more pronounced obesity and insulin resistance, a sign of type 2 diabetes.
The researchers also found that the brains of the offspring had changed. The dopaminergic system, which plays an important role in motivation and reward, and the AgRP neurons, which control hunger and whole-body metabolism, reacted differently to high-fat food.
‘The brains of the offspring resembled those of obese mice, simply because their mothers had eaten a healthy food that smelled like fatty food”, explains Laura Casanueva Reimon, co-first author of the study.
The researchers found that fetuses are exposed to the smells of unhealthy foods while still in the womb and as newborns during breastfeeding through their mother’s milk. Artificial activation of neural circuits associated with the smell of fatty foods during the neonatal period was sufficient to trigger obesity in adulthood.
What does this mean for humans?
It is known that children of overweight mothers have an increased risk of becoming overweight themselves. The study suggests that the mere smell of fatty food during development can increase the risk of overweight and obesity later in life, even in lean and healthy mothers.
However, it is important to emphasize that in these experiments the mothers needed to ingest the food containing the fatty odors, as mere exposure to the smell alone did not lead to obesity in the offspring.
“What we discovered changes how we think a mother’s diet can influence the health of her children,” explains Sophie Steculorum, who led the study.
“Until now, the focus has mostly been on maternal health and the negative effects of eating a high-fat diet, such as the risk of gaining too much weight. But our results suggest that the smells fetuses and newborns are exposed to could influence their health later in life independently of their mother’s health.”
Flavouring agents as food additives
The researchers used various flavouring agents to create the diets used for their investigations and found that these often contained the same ingredients that are used as food additives. One of this additive alone was able to trigger the same effects in the offspring.
‘The findings point to the need for more research to understand how consuming these substances during pregnancy or breastfeeding could affect babies’ development and metabolic health later in life“, said Sophie Steculorum.
Key Questions Answered:
A: Yes. Exposure to fatty food odors during pregnancy and breastfeeding increased obesity risk later in life in animal models.
A: Brain systems involved in reward, motivation, and hunger regulation were permanently altered.
A: The findings suggest a possible risk pathway, but direct human studies are still needed.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this olfaction and obesity research news
Author: Katharina Link
Source: Max Planck Institute
Contact: Katharina Link – Max Planck Institute
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Fat sensory cues in early life program central response to food and obesity” by Sophie Steculorum et al. Nature Metabolism
Abstract
Fat sensory cues in early life program central response to food and obesity
Maternal obesity predisposes offspring to metabolic diseases. Here, we show that non-nutritive sensory components of a high-fat diet (HFD), beyond its hypercaloric, obesogenic effects, are sufficient to alter metabolic health in the offspring.
To dissociate the caloric and sensory components of HFD, we fed dams a bacon-flavoured diet, isonutritional to a normal chow diet but enriched with fat-related odours.
Offspring exposed to these fat-related odours during development display metabolic inflexibility and increased adiposity when fed HFD in adulthood independently of maternal metabolic health.
Developmental exposure to fat-related odours shifts mesolimbic dopaminergic circuits and Agouti-related peptide (AgRP) hunger neurons’ responses to phenocopy those of obese mice, including a desensitization of AgRP neurons to dietary fat.
While neither neonatal optogenetic activation of sensory circuits nor passive exposure to fat-related odours is sufficient to alter metabolic responses to HFD, coupling optogenetic stimulation of sensory circuits with caloric intake exacerbates obesity.
Collectively, we report that fat-related sensory cues during development act as signals that can prime central responses to food cues and whole-body metabolism regulation.
