Sniffing Chocolate Could Boost Your Leg Day Workouts and Curb Hunger

• Smelling dark chocolate before and during a leg workout helped participants perform more repetitions.
• Though the exact mechanism remains unclear, researchers suspect that certain scents trigger physiological changes that may affect physical performance.
• Other scents, including peppermint and citrus, have also been shown to affect exercise.

The smell of dark chocolate might help you get a few more reps on leg day at the gym.

New research suggests that simply inhaling the aroma before and during a workout could help people improve exercise performance without taking a single bite of chocolate.

In an exploratory study published in Frontiers in Physiology, researchers found that healthy young men completed significantly more repetitions during a leg-extension workout after smelling 90% dark chocolate than after smelling water, the experiment’s control. Participants exposed to the dark chocolate scent also reported feeling less hungry and fuller. 

A milk chocolate scent also improved performance, though to a lesser extent, and appeared to produce a different psychological response.

The study adds to a growing body of research suggesting that odors may influence athletic performance through complex interactions between the brain, appetite, and perception. 

“Their findings, showing greater improvements in performance with dark chocolate, align well with other findings in the literature, where lower appetite and higher fullness are associated with better performance,” said Marie-Eve Mathieu, PhD, Canada Research Chair, physical activity and juvenile obesity, at Université de Montréal. Mathieu wasn’t involved in the research.

Mathieu has published research on the effects of scents, including peppermint, ammonia, lavender, and citrus, on athletic performance.

However, given the limitations of the experiment, experts stress that the new study should be viewed as an intriguing first step, not definitive proof. The study was relatively small, involved only young resistance-trained men, and evaluated performance during a single type of exercise performed after an overnight fast. 

“We need to be cautious about drawing broad conclusions,” said Kristin Kirkpatrick, president of KAK Consulting and a dietitian at the Cleveland Clinic Department of Wellness & Preventive Medicine in Ohio.

Smelling dark chocolate led to more reps

To explore whether chocolate odors could influence exercise performance, researchers recruited 23 healthy men who regularly participated in resistance training. 

Each participant completed three laboratory sessions, one with each of three different odors: 90% dark chocolate, 60% milk chocolate, and a water-based control. The sessions were separated by at least four days, and all testing took place after an overnight fast lasting at least 10 hours.

Before exercising, participants smelled one of the prepared odor samples for 30 seconds at several time points while rating their hunger, fullness, desire to eat, and how pleasant they found the scent. They then performed repeated sets of leg extensions until they could no longer continue. Before each new set, they again smelled the assigned odor.

The results showed clear differences between the three scents.

Participants exposed to the 90% dark chocolate odor completed an average of 18 more repetitions than they did during the control condition. The scent of milk chocolate resulted in nine more repetitions than the control group. Researchers also found that participants completed about one additional exercise set after smelling dark chocolate compared with either milk chocolate or the control.

Researchers also found that the scents had distinct effects on feelings related to satiety and perceived exertion.

Before exercise, the dark chocolate odor consistently reduced hunger, desire to eat, and prospective food consumption while increasing feelings of fullness compared with both milk chocolate and the control condition.

Milk chocolate, on the other hand, did not produce the same appetite-suppressing effect. Instead, participants consistently rated its aroma as more pleasant than either dark chocolate or the control.

“The fact that this study investigated appetite sensations and pleasantness as potential mechanisms is a strength. In this study, dark chocolate appears to work through a reduction in appetite and an increase in fullness, while milk chocolate appears to work through pleasantness,” Mathieu said.

The exact mechanisms by which scent may improve performance remain unclear. The authors suggest it could be linked to the endocrine cephalic phase response, the body’s anticipatory physiological reaction to the sight, smell, or taste of food before it is actually consumed. The researchers say that scents, including chocolate, could trigger physiological changes that affect performance. 

The study has several important limitations that temper the findings, including its size and its limited population of men with weightlifting experience. However, the results are intriguing enough to warrant more research.

“Replication in other populations, such as older individuals and individuals with different body sizes or training habits, is now supported, as are deeper investigations of the mechanisms, given that they found significant improvements in leg extension performance,” Mathieu said.

How dark chocolate and scent can affect exercise performance

Dark chocolate has attracted scientific attention for years because of compounds known as flavonoids — naturally occurring plant chemicals found in cocoa and other plants that have been linked to a variety of health benefits. 

Although eating dark chocolate and smelling it are very different experiences, its reputed health benefits make it an interesting candidate for studying whether scent cues alone can influence performance.

“Dark chocolate has been widely studied for its health benefits, and studies show that the flavonoids may play a role in better brain health, vascular health, and potentially even reduce the risk of type 2 diabetes,” Kirkpatrick said.

The psychological effects noted in this study, such as feelings of satiety when compared to milk chocolate, are supported in some prior research. However, the health benefits of dark chocolate have traditionally come from eating it, not inhaling its aroma. 

The findings also fit within a broader area of sports science examining how different scents affect physical performance.

A 2024 review by Mathieu and colleagues of 19 studies examining olfactory stimulation and exercise found that several common odors have modest performance-related effects. However, results vary considerably depending on the scent, the exercise performed, and the study design. 

• Peppermint has been associated with improvements in sprinting, running performance, push-ups, and perceived effort in some experiments. 
• Ammonia, a familiar smell in some weight rooms because of its use in smelling salts, has been linked to increased alertness.
• Lavender has been investigated for its calming properties and potential influence on recovery and anxiety.
• Citrus may improve feelings of well-being during physical activity. 

But what about that essential question: will sniffing chocolate really help you pump out a few more reps?

For now, experts say the practical message is one of cautious curiosity rather than a new workout recommendation.

“If you do more or simply feel better with a pleasant and specific smell, it is an interesting avenue to explore,” said Mathieu.

“Smelling mint, citrus, or chocolate is safe compared with some other practices, and these scents have been shown to improve either perceived or actual performance. It is important to highlight that the improvements remain small and that you will not double your performance simply by using a smell,” Mathieu said.