You’ve probably heard the question at least once, and if you train women regularly, maybe a dozen times: “Should I train differently depending on where I am in my cycle?” It’s a fair question and one that’s been floating around fitness circles and social media feeds for years. There’s this idea that women burn more fat at certain times of the month and that tailoring training or nutrition to hormone fluctuations could give them a bit of a fat-burning edge.
But how much of that is actually backed by research? And how much is just another catchy myth with a sprinkle of science?
A recent 2025 study by Kono and colleagues took a closer look, asking whether the phase of the menstrual cycle really affects how much fat women burn during moderate-intensity exercise, particularly fat that’s been consumed just before training. The results might surprise you. Or, if you’re someone who’s taken a personal trainer course focusing on women’s health, they might actually confirm what you already suspected: things aren’t as black-and-white as Instagram reels make them out to be.
Quick Refresher
Before we go too far into the science, let’s have a quick recap of what’s happening hormonally during a typical menstrual cycle, since it plays such a big role in how people think exercise might be affected.
The menstrual cycle is usually divided into two main phases: the follicular phase and the luteal phase. The follicular phase kicks off on the first day of menstruation and runs up until ovulation (roughly days 1–14 in a textbook cycle). Oestrogen starts off low and gradually rises as the body prepares to release an egg.
Once ovulation happens, we enter the luteal phase (roughly days 15–28). This is when both oestrogen and progesterone levels rise, with progesterone taking the lead. It’s also the phase where some women report feeling more fatigued, bloated or less motivated to train, partly due to that hormonal cocktail.
Oestrogen tends to have a more anabolic, energy-efficient effect, promoting better glucose uptake and potentially greater fat use during endurance work. Progesterone on the other hand, has more of a thermogenic and catabolic effect, which can increase resting body temperature and sometimes make training feel a bit tougher.
That said, these effects are subtle and not all clients will notice them. But understanding this backdrop gives personal trainers a better sense of when and why some women may feel changes in energy, performance, or recovery across the month. It’s also a key concept in any women’s health specialist personal trainer course, where hormone literacy is just as important as rep schemes and macros.
The Science Behind the Question
This study was a bit different from the usual “hormones and exercise” research. Instead of just looking at fat burned in general, the researchers gave participants a labelled fatty acid (13C-palmitic acid, which is basically traceable dietary fat) and measured how much of it was metabolised during exercise. That let them focus specifically on exogenous fat oxidation, that is the fat which was eaten, not stored.
Nine young, healthy women who were all habitually active but not elite athletes, completed two 30-minute cycling sessions at 50% of their peak oxygen uptake (VO₂peak). One session took place during the early follicular phase, just after menstruation, when oestrogen and progesterone levels are low. The other session was during the mid-luteal phase, when both hormone levels are higher.
The researchers measured everything from fat and carbohydrate oxidation to blood glucose and heart rate. And after all the data crunching, they found that while fat metabolism increased during the session, as you’d expect, it didn’t really differ between menstrual phases.
In short, whether the participants were in their follicular or luteal phase didn’t make a meaningful difference in how much dietary fat their bodies burned during exercise.
But What About Longer Workouts?
This is where things get a bit more nuanced. The study sessions were just 30 minutes long. That’s pretty typical for a moderate-intensity workout but it’s not necessarily long enough to bring out the full effects of hormonal fluctuations.
Interestingly, the researchers noted that the “effect sizes”, meaning the magnitude of change, increased over time. So while the differences weren’t statistically significant within those 30 minutes, it’s possible they might become more pronounced in longer sessions.
This idea lines up with previous studies. For example, Campbell et al. (2001) found that women oxidised more fat and less carbohydrate during a two-hour cycling session in the luteal phase compared to the follicular phase. Devries et al. (2006) had similar findings during 90-minute workouts.
So it’s not that hormones don’t matter but their impact may only become clear when exercise sessions are longer or more intense. For day-to-day personal training sessions, which often sit in that 30–45 minute range, the cycle phase probably isn’t a game-changer.
If you’ve completed a personal trainer course focusing on women’s health, this is the sort of critical context that can help you interpret research with a trained eye, not just repeat the headlines.
Do We Need to Change the Plan?
Here’s the honest answer: not necessarily.
The study’s results support the idea that for moderate, short-to-mid-length workouts, most women don’t need to drastically change their programme based on their menstrual cycle. In fact, doing so might overcomplicate things unnecessarily, especially when the real difference lies more in how a woman feels than what’s happening hormonally behind the scenes.
That said, if a client prefers lighter sessions in the days before their period, or they feel particularly strong and energetic mid-cycle, there’s no harm in leaning into that. Let the science guide you, but let your client’s lived experience lead the way.
If they’re training for endurance events or long cardio sessions, it might be worth paying more attention to the phase, especially if you’re planning high-volume fat-burning workouts. But otherwise, keep it simple. Consistency matters more than cycle-matching.
Should Clients Eat More Fat Before Training in the Luteal Phase?
This one’s been floating around for a while too; the claim that eating fat before working out during the luteal phase helps burn more fat. It sounds logical on the surface, especially with all the talk of hormonal shifts. But in practice, the research just doesn’t back it up.
The Kono study gave participants a pre-exercise dose of labelled dietary fat to track what happened to it. The result? No significant difference between menstrual phases in how much of that fat was oxidised. So while fat metabolism went up during exercise, as expected, it didn’t depend on where participants were in their cycle.
The takeaway here is that what you eat before training may matter more than when in your cycle you eat it. Timing, quantity, and type of fuel are all important, but let’s not overstate the effect of hormones on fat oxidation in short, moderate sessions.
For trainers who’ve studied this in a personal trainer course, this finding fits neatly into the wider message of evidence-based, client-led coaching.
Managing Expectations (and Myths)
Perhaps the most important takeaway for fitness professionals is this: be the voice of reason. Clients often come in with half-formed ideas picked up from TikTok or well-meaning influencers who swear that syncing your workouts to your cycle is the key to fat loss.
It’s not.
You don’t need to dismiss their concerns, but you do need to guide them with science. A good approach is to validate how they feel. Let them know that some people do feel better at certain points in their cycle, and that’s completely valid. Then bring in the evidence: “What we know from research is that for most workouts, the phase of your cycle isn’t going to massively affect how your body uses fat for fuel.”
If they feel amazing during the follicular phase and sluggish during the luteal? Great. Adjust sessions based on how they feel. But always anchor your advice in reality, not cycles on a chart.
What This All Means for Trainers
When it comes to fat metabolism and the menstrual cycle, the current research points to one clear message: there’s no need to overhaul your client’s training plan based on their hormonal profile unless you’re working at longer durations or with very cycle-sensitive individuals.
What matters more is how they feel, what their goals are and whether they’re consistent with their training and nutrition.
Stay informed. Stay client-centred. And keep questioning the buzzwords. That’s what sets apart a trainer who’s simply qualified from one who truly understands, which is exactly what a great personal trainer course focusing on women’s health aims to teach.
References
- Kono, H., Miyashita, M., Furuta, K., Iwagaki, S., Sakamoto, T., & Ueda, S. (2025). Effects of the menstrual cycle on the exogenous fat metabolic rate during moderate-intensity exercise. Journal of Education and Health Science, 70(3), 212–222. Click here to review the full research article.
- Campbell, S. E., Angus, D. J., & Febbraio, M. A. (2001). Glucose kinetics and exercise performance during phases of the menstrual cycle: effect of glucose ingestion. American Journal of Physiology-Endocrinology and Metabolism, 281(4), E817–E825. Click here to review the full research article.
- Devries, M. C., Hamadeh, M. J., Phillips, S. M., & Tarnopolsky, M. A. (2006). Menstrual cycle phase and sex influence muscle glycogen utilisation and glucose turnover during moderate-intensity endurance exercise. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 291(4), R1120–R1128. Click here to review the full research article.
The Science of Women’s Fitness Starts Here
If you’re thinking about becoming a personal trainer and want to specialise in women’s health, the Women’s Health & Exercise Specialist & Master Diplomas™ from TRAINFITNESS are a must. You’ll learn all about the physiological changes that happen across the menstrual cycle, menopause, pregnancy and more, as well as how to design effective, supportive programmes for female clients at every life stage. Take fat metabolism, for example: a 2025 study found that women didn’t significantly burn more dietary fat during exercise in one menstrual phase over another, but that exercise duration had a bigger impact than hormones alone. In fact, the study showed that fat oxidation increased steadily over time, regardless of cycle phase. These are the kind of insights that will set you apart from the average PT and they’re exactly what this course delivers. Ready to train smarter, not just harder? This is where you start.
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