The health and fitness space can be a minefield, especially when it comes to the research we lean on to guide us. One of the most frustrating and dangerous trends I’ve noticed recently is the tendency to use studies that are cherry-picked and heavily generalized, often misapplied to women’s health. Worse yet, it’s often done by men who are mansplaining female physiology by quoting studies that weren’t even designed for women in the first place.
Now, let’s talk about one recent example that’s stirring the pot and why it’s a classic case of mansplaining with citations.
The Context: Fear-Mongering Disguised as Science
A recent incident involved two male coaches who were using their platform to discredit Dr. Stacy Sims, a well-respected expert in female physiology. They were addressing the topic of fasted training—which is often pushed as a “one-size-fits-all” solution for fat loss, muscle gain, and overall performance—and using outdated research that doesn't even apply to women to make their points.
The specific claim? They argued that fasted training does not have negative effects on hormones, fat loss, or muscle retention in women—as long as daily caloric totals are appropriate. The thing is, this statement is misleading and problematic, especially when it’s based on studies that don’t focus on women’s health in the first place.
But here’s the kicker: One of the women they’re trying to discredit is Dr. Stacy Sims, the very researcher contributing to the science behind intermittent fasting (IF) for women.
Let’s break down the citations used by these coaches and how they’re misinterpreted, leaving out key pieces of research that show the full picture.
The Research They Cited: A Misstep in Applying Studies to Women
Study 1: (doi.org/10.3390/jfmk2040043)
This meta-analysis from 2017 includes just 96 participants, and it’s not focused on women specifically. It’s also far from comprehensive, lacking any assessment of hormonal shifts, menstrual cycles, or the long-term effects of fasting on women’s endocrine functions. So, saying “fasted training has no hormonal effects in women” based on this study? That’s a major stretch.
Study 2: PMID: 24299050 (2013)
This one focuses on resistance training in young men, comparing fasted vs. fed states. No hormone tracking. No menstrual cycle analysis. Nothing that applies to women or considers their hormonal fluctuations over the course of the month. Not exactly the gold standard for proving anything about women’s physiology.
Study 3: PMID: 23382817 (2013)
Here, we’re looking at a study on resistance training and nutrient timing, but once again, the research subjects are young adult males. It focuses on body composition without any consideration for hormonal differences between men and women, let alone how these effects might change during different phases of the menstrual cycle or menopause.
The Bigger Picture: What’s Missing from These Studies?
The three studies cited above don’t even address the complexities of female physiology. Not once do they consider the following:
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The intricacies of the menstrual cycle
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Perimenopause or menopause
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Hormonal impacts beyond just body weight and muscle mass
When we talk about female athletes, we need to consider how hormonal fluctuations, including the influence of estrogen, testosterone, and progesterone, affect everything from energy levels to muscle recovery and fat burning. These studies don’t touch on any of that.
The Nuance Missing from These Studies:
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Hormonal fluctuations: Women experience fluctuations in hormones, which significantly affect things like fuel usage, recovery, and stress responses.
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Menstrual cycle and performance: Women’s energy and strength can vary depending on the phase of their menstrual cycle. For example, training fasted during the luteal phase, when progesterone is elevated, may cause more stress on the body.
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Menopause and perimenopause: These stages in a woman’s life bring unique challenges, with changes in estrogen and progesterone levels that affect stress tolerance, muscle preservation, and overall metabolism. Surgical menopause is a whole other situation we won't even dive into today.
Dr. Stacy Sims and the Science They’re Ignoring
Dr. Stacy Sims has done years of research focused specifically on how fasting impacts female physiology. Her work has uncovered some crucial points that these studies fail to mention:
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Fasted training can increase cortisol in women, especially in the luteal phase or those already experiencing high stress due to hormonal shifts (like in menopause).
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Prolonged fasting or under-fueling can lead to disruptions in thyroid function and sex hormones—problems that might not be immediately obvious but can affect long-term health and performance.
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The idea that “fasted is fine if your calories are fine” ignores the nuance of hormonal signaling and stress loads, which vary greatly between men and women, and across different stages of life.
When male coaches dismiss this complexity, they’re not just misrepresenting science—they’re erasing the lived experiences of women.
The Science Isn’t Black and White: Fasting for Women, The Pros and Cons
There is solid research out there on fasting and its impacts on women. But the key is that it’s not all one-size-fits-all. There are both benefits and risks, depending on the context, timing, and the individual.
Evidence Supporting Fasting in Women:
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Fat loss & insulin sensitivity: Studies show that intermittent fasting (IF) can improve fat loss and insulin sensitivity in both men and women.
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Cellular repair: Fasting activates autophagy, a process of cellular repair, which can benefit long-term health.
Evidence Against Fasting or Caution for Women:
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Menstrual cycle disruptions: Extended fasting or severe caloric restriction can disrupt menstrual cycles, especially in the follicular phase.
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Hormonal imbalances: Chronic fasting can increase cortisol levels, impair thyroid function, and negatively impact reproductive health and bone density.
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Impact during perimenopause and menopause: Women in these life stages are particularly vulnerable to stress-related hormonal disruptions, which fasting can exacerbate.
Science is Nuanced, Not One-Size-Fits-All
The studies cited by the coach who called out Dr. Sims don’t prove that fasting is universally harmless for women. They don’t speak to the complexities of female physiology, and they certainly don’t account for women in perimenopause or surgical, or natural post-menopause, or even those under chronic stress. By presenting this outdated, male-centered research as conclusive evidence, these coaches are oversimplifying an incredibly nuanced issue.
The real science involves carefully considering female physiology, understanding how hormonal shifts impact fuel usage, recovery, and stress responses, and approaching fasting with the understanding that it might not work the same way for women as it does for men. We need more studies on women’s health—specific studies—to get to a place where we can make truly evidence-based recommendations that work for all women.
So, before you take anyone’s word for it, check the receipts. Because as we’ve seen here, not all research is created equal, and context matters. If you’re a coach or an athlete, you owe it to yourself to be well-versed in women-specific science—especially when it comes to something as complex as fasting.