Can You Gain Weight Through Smell? Unpacking the Link Between Olfaction and Obesity

December 17, 2025 •

4 min read

In a surprising 2017 study on mice, researchers found that rodents with an enhanced sense of smell gained significantly more weight on a high-fat diet than those with an impaired sense of smell, despite eating the same amount. This finding challenges the simple calorie-in, calorie-out model and suggests that you can gain weight through smell indirectly by influencing metabolic processes.

Quick Summary

Smelling food does not transfer calories, so direct weight gain is impossible. However, scientific research shows that a robust sense of smell can influence metabolic processes and appetite, potentially contributing to weight gain by altering how the body stores or burns fat.

Key Points

Indirect Weight Gain: The scent of food can influence metabolic processes, potentially causing the body to store more fat and burn fewer calories, according to animal studies.
Calorie Inhalation Myth: It is biologically impossible to absorb calories through smell, as calories only come from ingested food or drink.
Metabolic Perception: Research shows that weight gain is not solely dependent on caloric intake but also on how those calories are 'perceived' by the body's sensory systems.
Appetite and Craving: Food aromas prime the body for eating, triggering cravings and potentially leading to overconsumption of palatable, high-calorie foods.
Human vs. Animal Studies: While mouse studies show a direct metabolic effect, human studies highlight how smell impacts eating behavior and food choice, which indirectly affects weight.
Hyposmia and Weight: Loss of smell (hyposmia) has been linked to weight changes, with some individuals gaining weight by seeking high-calorie foods to compensate for reduced flavor.

Separating Fact from Fiction: The Science of Smell and Weight

The idea that merely smelling food can make you gain weight sounds like a myth, but recent scientific research suggests there's a kernel of truth to the concept. While you cannot inhale calories from a scent, the olfactory system plays a much larger role in regulating appetite, metabolism, and overall energy balance than previously understood. This discovery moves beyond the simple notion of smell-induced cravings and delves into the intricate metabolic pathways that can be influenced by sensory input.

The Landmark Mouse Study and Its Implications

A 2017 study published in the journal Cell Metabolism by researchers at the University of California, Berkeley, provided compelling evidence linking olfaction and metabolism. The experiment involved three groups of mice fed an identical high-fat diet:

Normal-smelling mice: Gained weight as expected on the high-fat diet.
“Super-smeller” mice: Genetically engineered to have a heightened sense of smell, these mice gained significantly more weight than the normal-smelling group.
Disabled-smell mice: Had their sense of smell temporarily knocked out. Despite eating the same high-fat diet, they gained much less weight than their counterparts. Even more remarkably, when the researchers disabled the sense of smell in obese mice, they lost a significant amount of weight.

These results led researchers to hypothesize that the sensation of smell can trigger the brain's reward system, potentially influencing whether the body burns calories for energy or stores them as fat. In a world of tempting aromas, a keen sense of smell might signal to the body that a high-calorie feast is approaching, encouraging it to be more efficient at storing, rather than burning, those calories.

How Smell Influences Eating Behavior in Humans

While the direct metabolic effects seen in the mouse study may not translate perfectly to humans, the sense of smell plays a powerful role in human eating habits. It affects us in several distinct ways:

Appetite Stimulation: The aroma of food can prime the body for eating, triggering the cephalic phase of digestion. This includes the release of insulin, which can increase feelings of hunger and potentially influence energy storage.
Craving and Pleasure: Smell is the primary component of flavor perception. A rich aroma increases the pleasure derived from eating, which can lead to overeating or choosing more palatable, often energy-dense, foods.
Compensatory Eating: Studies on individuals with a reduced sense of smell (hyposmia or anosmia), including those affected by COVID-19, show varied effects on weight. Some lose weight due to decreased food enjoyment, while others gain weight by seeking out more intense, often higher-calorie, flavors to compensate for the lack of olfactory gratification.

Common ways smell impacts our diet:

Triggering cravings for specific foods.
Influencing food choices towards more flavorful (and often unhealthier) options.
Enhancing the perceived reward of eating, potentially leading to overconsumption.
Causing confusion regarding satiety cues, as a lack of smell can interfere with the brain's perception of having eaten enough.

Comparison: The Calorie Myth vs. The Metabolic Influence


Aspect	The Calorie-Inhalation Myth	The Metabolic-Influence Theory
Mechanism of Weight Gain	Claims that you can inhale calorie particles from food scents.	Explains that smell triggers neurological and metabolic responses, altering how the body processes food.
Scientific Validity	Zero. Calories can only be consumed through ingestion (eating or drinking).	Backed by animal studies, with growing evidence of related mechanisms in humans.
Effect on the Body	Suggests a passive, impossible absorption of energy.	Details an active, complex interaction between the senses, brain, and metabolic systems.
Key Takeaway	A complete falsehood based on misunderstanding what a calorie is.	A nuanced and ongoing area of research with practical implications for health.

Practical Implications: Can You Use Smell to Your Advantage?

Understanding the link between smell and metabolism opens up new avenues for behavioral strategies related to weight management. Instead of focusing on calorie-counting alone, integrating sensory awareness can be beneficial.

Mindful Eating: By paying closer attention to the aroma, taste, and texture of food, you can increase your satisfaction with less quantity. The enhanced sensory experience can lead to a more profound feeling of satiety.
Environmental Control: If certain food smells trigger powerful cravings, a simple strategy might be to limit exposure to those aromas. This is especially relevant in environments where tempting, high-calorie foods are constantly being prepared or sold.
Boosting Satiety Signals: Some research suggests that a heightened sense of smell can actually help regulate appetite by improving satiety signals after a meal. For individuals with a weakened sense of smell, exploring ways to enhance flavor perception could be a key to better appetite control.

Conclusion

So, can you gain weight through smell? The answer is no, not directly by inhaling calories. However, the science is clear that the scent of food is a powerful cue that can significantly influence our appetite and metabolism, affecting how our bodies manage fat storage. The direct metabolic shift observed in animal models, combined with the behavioral and physiological changes documented in humans, paints a complex picture where our sense of smell is an active player in the regulation of our weight. As research continues, the intricate interplay between our senses and our health will undoubtedly reveal more secrets about how we can best manage our bodies. For now, incorporating mindful eating and sensory awareness can be a valuable tool in any weight management strategy.

For a deeper dive into the metabolic effects of olfaction, the study published in Cell Metabolism is a key resource.

Frequently Asked Questions

No, it is impossible to inhale calories. Calories are a measure of energy that can only be obtained through ingesting food or drink. The molecules that make up scents are infinitesimally small and contain no caloric energy.

The sense of smell can influence weight gain by impacting appetite and metabolic processes. A powerful food aroma can trigger the cephalic phase of digestion, affecting hormones and signaling the body to potentially store more energy, according to animal studies.

Yes. A 2017 study at UC Berkeley found that mice genetically engineered with a heightened sense of smell gained significantly more weight on a high-fat diet than control mice, despite consuming the same amount of food.

The mice with a temporarily impaired sense of smell gained much less weight than the control group when fed the same high-fat diet. In some cases, obese mice lost weight after their sense of smell was disabled.

While the direct metabolic effects observed in mice are not confirmed in humans, the research highlights how powerful sensory perception is in regulating metabolism. It also helps explain how smell influences appetite, cravings, and food choices in people.

The relationship is complex. Some people who lose their sense of smell (e.g., from COVID-19) may lose weight due to decreased enjoyment of food, while others may gain weight by seeking out more intense, high-calorie flavors to compensate.

The cephalic phase is the initial physiological response to food that is seen, smelled, or thought about. The aroma of food initiates this phase, triggering saliva production and insulin release, which prepares the body for digestion and can stimulate appetite.