The smell of dark chocolate might do more than make people think about dessert.
A small new study suggests that smelling chocolate before and during strength training may reduce feelings of hunger and even help people complete more exercise without making the workout feel harder.
Researchers from the University of Malaya studied how food smells affect appetite and physical performance during resistance exercise. Their results suggest that the brain’s response to familiar food aromas may influence both how hungry people feel and how much work their muscles are willing to perform.
Smell has a powerful connection with the brain. Unlike many other senses, odors are closely linked with areas involved in memory, emotion, reward and appetite, which helps explain why the smell of a familiar meal can instantly bring back memories or make someone hungry.
The researchers wanted to know whether smell could also affect exercise. Previous studies have examined music, caffeine and other factors that may influence workout performance, but much less is known about whether food aromas can change how people feel and perform while lifting weights.
The study included 23 healthy men in their early to mid-20s who had some experience with resistance training. Participants were exposed to one of three samples: melted dark chocolate containing 90% cocoa, melted milk chocolate containing 60% cocoa, or water with no food smell.
Before the experiment, the participants had gone without food for at least 10 hours. This meant they were exercising while hungry, making it easier for the researchers to detect whether the chocolate aromas changed appetite-related feelings.
The men performed leg extensions, an exercise in which a person sits and straightens the knees against resistance. Researchers measured how many repetitions they could complete and asked them about hunger, fullness, desire to eat and how much they intended to eat.
Participants smelled the samples before exercise and between sets. The two chocolate aromas produced different effects, suggesting that not every pleasant food smell influences the body and mind in exactly the same way.
Dark chocolate had the clearest effect on appetite. Compared with milk chocolate and the water control, men exposed to the 90% cocoa smell generally reported less hunger, less desire to eat, lower intention to eat and a stronger feeling of fullness.
Milk chocolate produced a different response. Participants rated its smell as more pleasant than dark chocolate or water, but it did not appear to reduce basic feelings of hunger in the same way.
Both chocolate smells were linked with better exercise performance. According to the researchers, exposure to dark chocolate odor was associated with about 18 additional leg-extension repetitions compared with water, while milk chocolate was associated with about nine additional repetitions.
Perhaps most interestingly, the participants did not report feeling that they were working harder. Senior author Dr. Mohamed Nashrudin bin Naharudin said the increase in total training volume without a matching increase in perceived effort was an intriguing result.
The researchers think learned associations with food may help explain the findings. People develop strong expectations about familiar foods over many years, and simply smelling a rich food may prepare the brain and body for what normally happens when that food is eaten.
Dark chocolate, for example, may be associated with a rich and filling food. Its aroma could therefore create an expectation of fullness, while the sweeter smell of milk chocolate may act more as a pleasant reward that improves the experience of exercising.
The study was published in the scientific journal Frontiers in Physiology. It adds to evidence that sensory information can influence exercise behavior, but the findings are still preliminary and should not be treated as proof that smelling chocolate is a reliable workout aid.
There are several important limitations. Only 23 people participated, all were young men with moderate training experience, and the researchers did not measure hormones, brain activity or other biological signals that could explain exactly why the smells produced these effects.
The chocolate samples may also have differed in smell strength, while the control sample was simply water and had no odor. Participants therefore may have realized when they were receiving the control condition, which could have influenced expectations and performance.
The study is nevertheless an interesting demonstration of how strongly the brain can respond to smell. Larger experiments involving women, older adults, different foods and carefully matched control odors will be needed to determine whether the effect is real, repeatable and useful outside the laboratory.
For now, smelling dark chocolate should not be considered a replacement for proper nutrition, rest or evidence-based training. But the findings suggest that the sensory environment around exercise may influence performance in ways scientists are only beginning to understand.
If you care about nutrition, please read studies that whole grain foods could help increase longevity, and vitamin D supplements strongly reduce cancer death.
For more information about nutrition, please see recent studies about natural coconut sugar that could help reduce blood pressure and artery stiffness, and whey and soy protein may reduce inflammation in older people.
Source: University of Malaya.
