Early exposure to fat-related food smells can shape lifelong obesity risk. But here’s where it gets controversial: new research suggests that sensory cues from fat encountered before birth and in early life may rewire brain and metabolic responses to fat, increasing obesity risk later on—even when maternal obesity or excess calories aren’t present.
A recent study in Nature Metabolism investigates how fat-related sensory cues during early development influence how the brain responds to food cues, overall metabolism, and obesity in adulthood. It’s a nuanced look at non-nutritive signals from food—such as odors—that accompany nourishment and could influence lifelong eating habits.
Impact of maternal obesity on children remains a major concern. A maternal diet high in calories and fat is linked to higher risks of obesity and metabolic disorders in offspring, including excessive gestational weight gain, insulin resistance, and adiposity. While strong correlations exist between maternal obesity or high-fat intake and child obesity, the exact factors driving metabolic programming are still being explored.
Beyond calories, food carries scent compounds that don’t provide energy but still shape development. Fetuses and newborns are exposed to both nutritious and sensory signals from food. Perinatal olfactory experiences can form sensory memories that guide food preferences and eating habits into adulthood. Understanding how non-nutritive cues from a fat-rich environment influence long-term dietary choices and metabolism is therefore essential.
About the study
Researchers created an isonutritional diet by flavoring normal chow with fat-related odors, separating the sensory cues from the caloric content. This allowed them to study how smell alone, independent of nutrition, could contribute to metabolic programming. They also developed bacon-flavored and butter-fat–based diets to model fat sensory cues without relying on pork-based ingredients. The fat-odor profiles included 155 volatile compounds, mostly aldehydes, ketones, and alcohols. Despite sharing similar sensory textures, the bacon-flavored diet (BFD) aligned more closely with lard-based high-fat diets in sensory terms, while its nutritional profile matched normal chow.
Key findings show that odors from fat can trigger molecular responses in olfactory neurons and that early exposure to fat-related sensory cues can alter metabolic outcomes later. In a mouse model where developing pups were exposed to fat smells (but not necessarily high-fat calories), certain adult metabolic responses—like brown adipose tissue activity and liver signaling pathways—were influenced by these early sensory experiences. Importantly, this effect occurred even in the absence of maternal obesity or insulin resistance, suggesting a distinct role for sensory exposure in shaping obesity risk.
Sex-specific timing emerged as well: lactation appears to be a highly sensitive window for females, while males may require exposure across a broader developmental period to show heightened responses to fat-rich diets. The study also demonstrated that early sensory exposure to fat cues could generalize to different high-fat diets, not just the pork-based variety, indicating a broader mechanism by which scent-guided programming can influence obesity risk.
Biological implications
Developmental exposure to fat-related sensory cues altered markers of thermogenesis and metabolic regulation in adulthood, such as reduced thermogenic gene expression and impaired agouti-related peptide neuronal responses to dietary fat. These changes point to a reduced metabolic flexibility and a primed tendency toward obesity when later faced with high-fat diets.
Bottom line
The research suggests that non-nutritive sensory cues from fat exposure during critical developmental windows may program central food processing and metabolic responses in ways that increase obesity risk later in life, independent of maternal metabolic state. This highlights the importance of considering the sensory environment during pregnancy and early development as a potential target for obesity prevention strategies.
For further reading, see Casanueva Reimon et al. (2025) Fat sensory cues in early life program central response to food and obesity, Nature Metabolism. DOI: 10.1038/s42255-025-01405-8.
