New research published in Nature Metabolism indicates that exposure to fat-related food odors before birth and during early life can alter brain and metabolic responses to fat, raising the risk of obesity later on. This effect was observed even when mothers were not obese and did not consume excess calories.
The study focused on how sensory cues associated with high-fat diets, particularly volatile odors, might influence lifelong dietary preferences and metabolic health. Researchers developed a diet for mice using normal chow flavored with bacon odors to separate the effects of nutrients from those of non-nutritive sensory components. This bacon-flavored diet shared a similar scent profile with traditional lard-based high-fat diets but matched the nutritional content of standard chow.
Mice exposed to these fat-related odors during development showed heightened metabolic responses when later presented with high-fat diets. The study found that this increased susceptibility to obesity was linked specifically to early-life exposure to fat smells, regardless of maternal weight or insulin resistance.
Researchers also discovered differences between male and female mice regarding sensitivity periods: females were most affected by exposure during lactation, while males required continuous exposure throughout development for similar effects.
Further analysis revealed that the altered odor profiles in amniotic fluid and milk changed the sensory environment for offspring both before and after birth. Mice exposed to these cues had reduced thermogenesis in brown adipose tissue and lower expression of genes related to heat production, indicating impaired metabolic flexibility as adults.
The findings suggest that early olfactory experiences may program future eating habits and metabolic outcomes, potentially increasing vulnerability to obesity across various types of high-fat diets.
"Developmental exposure to a maternal diet high in calories and fat is a significant risk factor for lifelong obesity and metabolic disorders. Several studies have confirmed the metabolic consequences of maternal high-fat diet (HFD) consumption, some of which include excess gestational weight gain, insulin resistance, and adiposity."
"Perinatal olfactory experiences form sensory memories that contribute to food preferences and eating habits into adulthood. Thus, it is crucial to understand how non-nutritive sensory cues from HFD during development lead to long term effects, particularly on dietary preference, intake, and metabolic responses, is crucial."
"The heightened obesogenic responses observed in BFDdev animals were triggered explicitly by developmental exposure to BFD, suggesting that early life is a critical time of vulnerability for metabolic programming by fat-related sensory cues. Notably, exposure to these cues during development alone could be sufficient to worsen HFDlard-induced obesity, regardless of maternal obesity or insulin resistance."
"Lactation may represent the period of greatest sensitivity to fat sensory cues in females. In contrast, males require exposure to BFD throughout the entire developmental period to exhibit heightened responses to HFDlard."
"Fat-related sensory cues can affect metabolism, influencing how the body responds to different diets. Although the exact match in sensory cues between early-life and adult obesogenic diets was not required for metabolic effects, some degree of sensory similarity may play a significant role in this association."
"These findings indicate that developmental exposure to HFD-related sensory cues impairs metabolic flexibility and homeostatic responses to HFD in adult mice."
"Developmental exposure to fat-related sensory cues caused a specific impairment in Agouti-related peptide (AgRP) neuronal responses to dietary fat. However, responses to key hormonal signals were unaffected."
