Smelling Dark Chocolate Before a Workout: What 23 Fasted Men Did Differently

If you've ever lifted weights before breakfast, you know how hard it can be to stay focused on a set when you're hungry. Researchers at the University of Malaya wanted to know if a smell could make that moment easier, and the smell they chose was chocolate.

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What happened when the lifters smelled chocolate

The team recruited 23 moderately trained young men and tested each of them three times on an empty stomach, in random order [1]. Before every set of leg extensions, the men sniffed one of three liquids: melted 90% dark chocolate, melted 60% milk chocolate, or plain water. The trial was double-blind, so neither the participants nor the researchers running the sessions knew which liquid was in use. Each set was ten repetitions at a heavy load, and the men kept going, set after set, until they could not complete another.

With the dark chocolate smell, the men completed about 18 more repetitions in total than with water (95% confidence interval 13.8 to 22.1). In case you haven't come across the term, a confidence interval is the range where the true value most plausibly falls, so the extra repetitions were most likely somewhere between 13.8 and 22.1. With milk chocolate, they completed about 9 more. Their ratings of how hard the work felt went up across the sets in every condition, and those ratings did not differ between conditions. Before the exercise started, the dark chocolate smell lowered the men's hunger ratings, while the milk chocolate smell was rated as more pleasant without much change in hunger.

This was a crossover trial, which means each man was his own comparison, and that design is a big help in a group this small. It is still 23 young men doing one exercise, and the authors describe the work as exploratory. They did not measure hormones or brain activity, so the explanation for the extra repetitions is a hypothesis for now.

Can a smell change how hungry you feel?

Other studies have also found that food smells can affect the body before any food is eaten. In a 2017 trial of 32 young women, researchers released mild food odors into the room [2]. Chocolate and beef smells increased saliva production, and the women went on to eat more of a chocolate rice dish than they did with no smell in the air. That is the opposite of the lifting study's result, where dark chocolate lowered hunger ratings. The two studies differ in their participants, in fasting, in what people did next, and in how strong the smell was, so their results can't be compared directly. What they have in common is that a smell on its own, before any food was eaten, produced measurable changes in appetite and behavior.

Smell responses also change with repetition. In a 2014 study, people smelled chocolate twenty times in a row, and those who liked it at first rated it steadily less pleasant as the trials went on [3]. If you were hoping to use a smell as a training aid, nobody knows yet if the effect holds up over weeks of use, because the chocolate study was too short to test that.

Hunger is information, and fasted training suits some bodies better than others

I find this study more interesting as a reminder of how closely appetite and effort are tied together than as a performance trick. Naturopathic medicine starts from that kind of whole-person view. Hunger is a signal from the body, and the brain weighs it against every other demand, including a set of leg extensions. The authors suggest that a familiar food smell may prompt the body to prepare for eating, which could make hunger less intense for a while. That is a reasonable idea, and it has not been tested directly yet.

Training on an empty stomach works well for some people and poorly for others. For clients with blood sugar swings, thyroid conditions, a history of disordered eating, or dizziness during exercise, my first question is if fasted training makes sense for them at all, before we look for ways to push through it. I do not have a clinic protocol built around smell, and I would never treat a sniff of chocolate as a substitute for eating well around your workouts.

Should dark chocolate go in your gym bag?

If you already enjoy training fasted and the idea appeals to you, smelling dark chocolate before a set is cheap and low-risk to try. Just keep in mind that the evidence behind it comes from one small study in young men. Three things would make me more confident in the result:

1. A replication in women, older adults, and people who are new to training. The current result applies to moderately trained men in their twenties.

2. Longer follow-up. Because smell responses fade with repetition [3], the effect in week six may look quite different from the effect on day one.

3. Your own body's feedback. If you get shaky or lightheaded during fasted sessions, that is a reason to talk with your provider about fueling, and a smell is the wrong tool for overriding it.

If you aren't sure fasted exercise fits your health history, bring it up at your next visit.

References

1. Fan X, Deng H, Ng JY, Ab Aziz AAHB, Naharudin MNB. Chocolate odor enhances resistance exercise performance through appetite suppression in the fasted state: an exploratory study. Front Physiol. 2026;17:1834757. PMID: 42495704. doi:10.3389/fphys.2026.1834757. Original digest link (press coverage, secondary): https://www.sciencedaily.com/releases/2026/09/260914102445.htm

2. Proserpio C, de Graaf C, Laureati M, Pagliarini E, Boesveldt S. Impact of ambient odors on food intake, saliva production and appetite ratings. Physiol Behav. 2017;174:35-41. PMID: 28259807. doi:10.1016/j.physbeh.2017.02.042

3. Ferdenzi C, Poncelet J, Rouby C, Bensafi M. Repeated exposure to odors induces affective habituation of perception and sniffing. Front Behav Neurosci. 2014;8:119. PMID: 24782728. doi:10.3389/fnbeh.2014.00119

This article is for education only and is not medical advice. Every body is different, so please talk with your own healthcare provider before changing how you eat, exercise, or use supplements.

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If this resonates with what you're experiencing and you'd like to explore a naturopathic approach, book a consultation with our clinic.