Sniffing chocolate could offer an unexpected boost to gym performance, a small study indicates.
Researchers found that the aroma of chocolate, particularly dark varieties, helped participants complete more leg extensions while simultaneously curbing hunger.
Writing in Frontiers In Physiology, experts from the University of Malaya in Kuala Lumpur suggested that familiar and appealing food scents might trigger a psychological shift in appetite, enhancing exercise output.
The study involved 23 healthy men, all in their early to mid-20s, divided into three groups.
Each group sniffed one of three samples: liquified dark chocolate (90 per cent cocoa), liquified milk chocolate (60 per cent cocoa), or a control water sample.
None of the gym-goers had eaten for the previous 10 hours.
For the research, they all performed leg extensions, which involves sitting down and extending the lower legs to lift a weight.
Leg extension performance was assessed before and during the training, with levels of hunger, fullness, desire to eat, and plans to eat in the near future assessed beforehand.
During the sets, hunger and desire to eat were also measured 30 seconds after the odour sample had been sniffed.
The results suggested that, compared to the water control and milk chocolate samples, sniffing dark chocolate consistently led to people reporting less hunger, reduced desire and intention to eat, and greater fullness before exercise.
However, even those sniffing milk chocolate had beneficial results in performance.
Across both types of chocolate, people also did not feel as though they were training harder but managed more exercise repetitions.
Senior author Dr Mohamed Nashrudin bin Naharudin said: “Sniffing a 90 per cent dark chocolate odour added about 18 more repetitions to participants’ leg extensions while a 60 per cent milk chocolate odour added about nine repetitions compared to the water control.
“Exposing moderately trained men to chocolate odours right before and between sets of resistance exercise significantly increased their overall training volume without increasing their perceived exertion.
“Seeing a substantial increase in repetitions without the athletes feeling like they were exerting themselves any harder is a fascinating psychobiological outcome.”
The researchers suggested the changes in appetite perception could be related to what people learn about smells from a young age.
Anticipating a food might have similar effects to when it is actually eaten, they suggested.
“The dark chocolate scent serves as a learned cue for a rich, bitter and highly satiating food, which essentially tricks the system into an anticipatory state of fullness,” Dr Nashrudin bin Naharudin said.
“Conversely, the sweeter milk chocolate scent acts more like a hedonic reward cue, enhancing training volume by creating a highly pleasant sensory environment rather than by shifting basic metabolic hunger signals.”
Although it has not been tested yet, other appealing foods could also have an effect, the team believes.
However, they said more work is needed, including on larger samples.
