Possibly, but only in a very specific experiment. A 2026 randomized, double-blind crossover study found that trained young men completed more repetitions in a fasted leg-extension test when exposed to prepared dark- or milk-chocolate odors than when exposed to a water-based control. The dark-chocolate condition produced the largest difference: 18 more total repetitions than control, with a 95% confidence interval of 13.8 to 22.1.
That result is preliminary. It does not show that smelling chocolate reliably improves workouts, endurance, strength, sports performance, or long-term training progress. The study used one single-joint exercise, one short laboratory protocol, 23 men, and odor delivered from jars rather than a precisely measured inhalation device.
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What the study actually tested
Fan and colleagues investigated whether chocolate odors affect appetite perception and resistance-exercise performance in a fasted state. The trial included 23 healthy men aged 18 to 30 who were moderately resistance trained: each had trained at least twice weekly for two years or longer.
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| Condition | Preparation | Exposure |
|---|---|---|
| 90% cocoa dark-chocolate odor | Commercial 90% cocoa chocolate melted and mixed with distilled water and propylene glycol | 30 seconds before each exercise set |
| 60% milk-chocolate odor | Dark chocolate and whole milk mixed with water and propylene glycol | 30 seconds before each exercise set |
| Water-based control | Propylene glycol vehicle without the chocolate odor preparation | 30 seconds before each exercise set |
The liquids were presented in jars. Participants and the people counting repetitions were blinded to coded conditions, and the order was randomized. The study was performed after an overnight fast.
The exercise protocol
Participants performed repeated leg-extension sets at 80% of their individually tested 10-repetition maximum. They rested 3.5 minutes between sets and continued each set to volitional exhaustion. The odor was presented before every set, not continuously throughout the workout.
This design answers a narrow question: whether a chocolate smell, delivered in a controlled morning fasted test, is associated with the amount of work a trained man can complete on a machine-based lower-body exercise. It does not test free-weight training, whole-body sessions, running, cycling, competition, or a normal fed workout.
What happened to repetitions and sets
Both chocolate odors outperformed the water control on total repetitions in this protocol. The dark odor had the strongest result.
| Outcome | 90% dark-chocolate odor | 60% milk-chocolate odor | What the comparison means |
|---|---|---|---|
| Total repetitions | 18 more than water; 95% confidence interval 13.8–22.1 | 9 more than water | These are group results from this study’s exact test, not a promised gain in an individual workout |
| Total sets | One more set than water; one more set than milk chocolate | The study reports no stated advantage over water for total sets | The dark condition produced the clearest volume difference |
| Perceived exertion | Ratings rose as sets accumulated, but did not clearly differ by odor condition | The study did not detect a condition difference in its post-set RPE measure | |
The confidence interval attached to the dark-versus-water repetition difference describes uncertainty around the study’s estimated group effect. It does not mean every participant would complete between 13.8 and 22.1 extra repetitions, and it is not a forecast for a different exercise, population, or training state.
Appetite, fullness and pleasantness findings
Before exercise, the dark-chocolate odor lowered participants’ self-reported hunger, desire to eat and prospective food consumption, while increasing reported fullness. The milk-chocolate odor was rated as more pleasant than the dark odor.
These were subjective ratings collected around the experiment. The researchers did not show that either odor changed blood glucose, hormones, metabolism, muscle activation or available energy. A lower hunger score is not evidence that a person had more fuel for exercise.
The performance and appetite patterns also did not establish a cause. The investigators performed exploratory mediation analyses to ask whether hunger, fullness or pleasantness could explain the extra repetitions. They could not establish that any of those ratings caused the performance difference. As the study conclusion states: “However, exploratory mediation analyses did not establish hunger, fullness, or pleasantness as explanatory mechanisms for the performance differences.”
Why this is not proof that chocolate scent is a workout aid
It was one small exploratory trial
Only 23 people took part, all of them young, trained men. A small sample can detect a striking result by chance, and it cannot establish how the effect would behave in a larger or more diverse population. There is no replicated body of trials showing that chocolate odor improves exercise performance.
The task was unusually specific
Leg extensions isolate the knee extensors and make repetitions easy to count. Real workouts involve multiple joints, technical skill, balance, pacing and different fatigue patterns. The paper itself says: “The findings primarily apply to resistance exercise volume in this specific lower-limb task.”
Participants were fasted
The overnight-fast condition is important because appetite and food cues may feel different before breakfast than after a meal. The result may not transfer to a fed workout, an afternoon session, or training after carbohydrate intake.
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Jars containing prepared liquids are practical for a laboratory experiment, but they do not measure the concentration each person inhaled or the amount reaching the nose over time. Differences in sniffing, breathing and adaptation could affect exposure. The authors identify this lack of precise olfactometry as a limitation.
The study did not test long-term outcomes
There was no multi-week training program, body-composition measurement, strength progression, recovery assessment or competition result. More repetitions in one session do not demonstrate greater muscle growth or better athletic performance over time.
Smelling chocolate is not the same as eating it
The intervention was an odor. Participants did not consume chocolate, cocoa or milk as a supplement before exercising. Therefore, the findings cannot support claims that eating a chocolate bar improves performance, that cocoa nutrients caused the result, or that a chocolate-flavored product will reproduce the effect.
The dark stimulus did use commercial 90% cocoa chocolate as an ingredient in the laboratory liquid. That makes a high-cocoa chocolate a comparable ingredient for understanding the method, not a validated food-based performance aid. The experiment did not test a retail bar eaten before training and did not validate a consumer scent product, diffuser or inhaler.
What could explain the result?
The study does not identify a mechanism. The researchers measured appetite and pleasantness ratings, but those measures did not statistically explain the performance differences. Several possibilities remain open: an odor could alter attention, expectation, arousal, food-related motivation or the way a participant approaches a difficult set. Those are hypotheses, not findings demonstrated by this trial.
The fact that milk chocolate was rated more pleasant while dark chocolate produced the larger repetition result also argues against a simple “more pleasant smell equals more performance” explanation. Likewise, perceived exertion increased across sets without a clear odor-condition difference, so the extra work cannot be reduced to a demonstrated lowering of RPE.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to interpret the result if you train
Use it as an interesting cue, not a substitute for preparation
For a healthy person who enjoys the smell, exposure to chocolate aroma is unlikely to replace sleep, adequate food, hydration, a sensible program or a warm-up. None of those factors was compared with odor in the trial, and the study offers no evidence that scent can correct poor preparation.
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Do not assume the effect will appear in your normal workout
The observed difference came from a fasted, repeated leg-extension test at 80% of 10-repetition maximum, with 3.5-minute rests and odors delivered before each set. A set of squats, a run, a team sport or a fed upper-body workout is a different physiological and psychological situation.
If you experiment, treat it as an unvalidated personal observation
Someone curious about the finding could keep the rest of training constant and compare sessions with and without a familiar chocolate smell. To make the observation less misleading:
- Keep the exercise, load, rest periods, time of day and pre-workout food the same.
- Alternate conditions in a randomized order rather than always using the odor on the days you feel strongest.
- Record repetitions, total sets, post-set effort and any discomfort, while recognizing that ordinary day-to-day variation can be large.
- Stop if the smell causes nausea, headache, breathing irritation or an allergic reaction, and do not inhale concentrated fragrance mixtures.
This kind of self-test cannot establish causation and should not be used to justify unsafe fasting, excessive volume or replacing a meal.
Who the findings may not represent
- Women and people outside the study’s 18–30 age range.
- Beginners, highly advanced athletes and people who train less than twice weekly.
- People exercising after eating rather than after an overnight fast.
- Endurance athletes, team-sport players and anyone performing movements other than the tested leg extension.
- People with food allergies, scent sensitivity, migraine triggers or respiratory conditions; the trial was not designed to assess safety for these groups.
Generalizing beyond these groups would require additional controlled studies that vary sex, age, training status, exercise mode, nutritional state and odor delivery.
Study registration and status
The public UMIN-CTR record identifies the trial as CHOCO-PERF and lists dark-chocolate odor, milk-chocolate odor and water-control exposures, each lasting 30 seconds. The registry describes a randomized, double-blind crossover design in healthy men aged 18–30 who had resistance-trained at least twice weekly for at least two years.
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The article reports that the trial was preregistered with OSF and retrospectively registered with UMIN on November 4, 2025. The published work characterizes itself as exploratory and proof-of-concept. Its abstract says further work is needed “to confirm the mechanisms and generalizability of these effects.”
What a convincing follow-up would need to test
A stronger evidence base would include larger samples, women and older adults, trained and untrained participants, fed and fasted sessions, and several exercises or sports. Researchers would also need precise olfactometry so each participant receives a measured odor concentration, along with objective physiological measures and preregistered primary outcomes.
Replication across independent laboratories would help determine whether the repetition increase is robust or specific to this experiment. Longer studies could then ask whether any acute volume difference affects strength, muscle size, recovery or performance over weeks. Until those studies exist, the chocolate-odor finding remains a narrow preliminary signal rather than a proven ergogenic strategy.
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