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Should Women Fast? Let’s Talk About It.
Dr Mindy Pelz vs Dr Stacey Sims
One minute fasting was the next best thing, the next we’re told women should never!
With so many conflicting arguments and a general lack of research in female health, we understand why we get so many questions about it from our clients at ATTIKA!
Fasting may have sparked your interest through the positive reinforcement given by Dr. Mindy Pelz with her book Fast Like a Girl. You may have more recently heard of Dr. Stacy Sims’ strong stance against fasting for women and that the science on fasting is only for men.
So, what’s the deal? Who should we listen to?
One expert says fasting can help regulate hormones and boost metabolism. The other says it can cause muscle loss and mess with your stress levels.
If you feel confused, you’re not alone. Let’s break it down.
The Case For Fasting – Dr. Mindy Pelz
Dr. Mindy Pelz is a functional medicine doctor with over 20 years of clinical experience, focused on women’s hormonal health, metabolic repair, and natural healing methods. She is not a research scientist but has worked extensively with women in real-life clinical settings. Her teachings are rooted in patient outcomes and practical applications. She is the author of Fast Like a Girl and host of the “Resetter Podcast,” where she educates on fasting, detox, and hormone cycling.
Dr. Mindy Pelz’s book Fast Like a Girl became popular because it speaks directly to women who want to feel more in control of their health. Her take? Women should fast, but not like men do.
Her method is based on syncing fasting with the phases of the menstrual cycle:
- Early Cycle (Days 1–10): Go for longer fasts, as estrogen is rising and you're more insulin sensitive.
- Ovulation (Days 11–15): Shorter fasts only - your body is working hard hormonally.
- Late Cycle (Days 20–28): Avoid fasting - your body needs more carbs to support progesterone and reduce stress.
Her approach is intuitive, and for many women she has worked with, it feels great: clearer mind, reduced bloating, stable energy. However, most of her evidence is anecdotal and clinical (rather than peer-reviewed research). Still, her message is empowering - listen to your body, and honour your cycle.
The Case Against Fasting - Dr. Stacy Sims
Dr. Stacy Sims is a PhD-level exercise physiologist and nutrition scientist. Her work is grounded in peer-reviewed research, and she has contributed significantly to the field of female physiology in sport and health. She has worked with elite athletes, military personnel, and leading universities, and is the author of ROAR and Next Level, both focused on training and nutrition for women. Her expertise lies in applying scientific data to optimise women’s performance and long-term health.
Dr. Stacy Sims is an exercise physiologist with a clear message: “Women are not small men.” Most fasting research has been done on males or postmenopausal women, and she says it’s risky to apply those findings to menstruating women.
Her concern? When women fast - especially if they also train, they may:
- Lose lean muscle
- Disrupt hormonal balance
- Spike cortisol (stress hormone)
- Under-eat, leading to fatigue and performance dips
She’s especially concerned about female athletes or active women who skip breakfast and train fasted. The risk of under-fueling and long-term damage is high, even if short-term results look “successful.”
Science or experience?
While both Dr. Pelz and Dr. Sims care deeply about women’s health, their approaches are built on very different types of evidence.
- Dr. Mindy Pelz’s work is based primarily on her own clinical experience and thousands of case studies from her community. This real-world insight can be incredibly valuable but her recommendations are not drawn from controlled studies or scientific trials. That means there may be confirmation bias, and not all outcomes are universally replicable.
- Dr. Stacy Sims, on the other hand, builds her conclusions from peer-reviewed research in exercise physiology and female endocrinology. Her recommendations are tested across populations, controlled for variables, and subject to scientific scrutiny.
So, while Dr. Pelz’s approach might feel empowering and may work well for some, it’s important to recognise that her conclusions haven't been scientifically validated. Dr. Sims’ caution, meanwhile, comes from data especially data focused on active women, hormonal function, and muscle preservation.
In short: if you’re looking for advice rooted in science, Dr. Sims holds a stronger evidence-based position.
So… Here’s our take
✅ Both voices matter. Dr. Pelz brings a fresh, empowering lens to women’s health, encouraging more body awareness. Dr. Sims brings the science and a reminder that unlike males, the female body needs consistent nourishment, especially under physical stress.
✅ We wonder whether Dr. Pelz advice for fasting from day 1 of menstruating is actually very intuitive of the female body. As you may have experienced, when women menstruate, we often have more cravings. We usually don’t like to stress the body at this time, and it is especially important to take care of what it is asking for. When we lose blood we also lose iron, it’s important to therefore replenish with iron rich foods. We would therefore say that if you are going to fast, to at least wait until bleeding eases and cravings reduce.
✅ Dr. Sims scientific research shows that muscle mass can be lost when we train fasted. Even if losing weight is the goal, losing muscle mass will reduce metabolism and therefore make any weight-loss results hard to sustain.
✅ With fasting having the potential to disrupt hormone balance and increase cortisol, fasting could cause some women to gain weight.
✅ There’s no one-size-fits-all answer. Some of you may genuinely thrive with light fasting during certain parts of your cycle. Some women report having more energy and increased focus. For those who struggle with over-eating, fasting can be used as a way to reduce calorie intake and put off addictive cravings.
✅ What we care about most at ATTIKA is sustainability, strength, and long-term vitality - not chasing trends or short-term fixes.
So… Should You Fast?
While it may be helpful for some women who feel like they’ve tried everything else, fasting doesn’t need to be the answer.
Instead, we encourage you to start with these foundational steps:
✅ Rebalance your meals. Make sure your breakfast includes enough protein (aim for 25–35g), fibre, and healthy fats to support blood sugar and satiety throughout the day.
✅ Eat earlier in the day. Most women do better when their larger meals are consumed earlier. Think: “front-loading” your energy when your metabolism is more active.
✅ Support your nervous system. Chronic stress, under-recovery, and poor sleep often mimic the symptoms people try to fix with fasting (like cravings, bloating, or stubborn weight). Address those first.
✅ Train smart. If you’re strength training, you need fuel. Skipping meals around your workouts may do more harm than good when it comes to hormone health and muscle preservation.
✅ Track, don’t guess. If you’re unsure what’s working, start tracking. Sleep, hunger, mood, energy, cycle… they’re all data points. And your body is always giving you clues.
If you’ve already dialled in the basics and still feel stuck, especially if you notice patterns of emotional eating, cravings, or low energy, then experimenting with fasting could be a tool. But only if you approach it with care:
👉 Do it in alignment with your cycle
👉 Track your mood, energy, and hunger
And if you’re ever unsure, ask us. We’re here to guide you through all the conflicting information and help you find what works for your unique body.
Because at the end of the day, your health journey should make you feel stronger, not smaller.
One minute fasting was the next best thing, the next we’re told women should never!
With so many conflicting arguments and a general lack of research in female health, we understand why we get so many questions about it from our clients at ATTIKA!
Fasting may have sparked your interest through the positive reinforcement given by Dr. Mindy Pelz with her book Fast Like a Girl. You may have more recently heard of Dr. Stacy Sims’ strong stance against fasting for women and that the science on fasting is only for men.
So, what’s the deal? Who should we listen to?
One expert says fasting can help regulate hormones and boost metabolism. The other says it can cause muscle loss and mess with your stress levels.
If you feel confused, you’re not alone. Let’s break it down.
The Case For Fasting – Dr. Mindy Pelz
Dr. Mindy Pelz is a functional medicine doctor with over 20 years of clinical experience, focused on women’s hormonal health, metabolic repair, and natural healing methods. She is not a research scientist but has worked extensively with women in real-life clinical settings. Her teachings are rooted in patient outcomes and practical applications. She is the author of Fast Like a Girl and host of the “Resetter Podcast,” where she educates on fasting, detox, and hormone cycling.
Dr. Mindy Pelz’s book Fast Like a Girl became popular because it speaks directly to women who want to feel more in control of their health. Her take? Women should fast, but not like men do.
Her method is based on syncing fasting with the phases of the menstrual cycle:
- Early Cycle (Days 1–10): Go for longer fasts, as estrogen is rising and you're more insulin sensitive.
- Ovulation (Days 11–15): Shorter fasts only - your body is working hard hormonally.
- Late Cycle (Days 20–28): Avoid fasting - your body needs more carbs to support progesterone and reduce stress.
Her approach is intuitive, and for many women she has worked with, it feels great: clearer mind, reduced bloating, stable energy. However, most of her evidence is anecdotal and clinical (rather than peer-reviewed research). Still, her message is empowering - listen to your body, and honour your cycle.
The Case Against Fasting - Dr. Stacy Sims
Dr. Stacy Sims is a PhD-level exercise physiologist and nutrition scientist. Her work is grounded in peer-reviewed research, and she has contributed significantly to the field of female physiology in sport and health. She has worked with elite athletes, military personnel, and leading universities, and is the author of ROAR and Next Level, both focused on training and nutrition for women. Her expertise lies in applying scientific data to optimise women’s performance and long-term health.
Dr. Stacy Sims is an exercise physiologist with a clear message: “Women are not small men.” Most fasting research has been done on males or postmenopausal women, and she says it’s risky to apply those findings to menstruating women.
Her concern? When women fast - especially if they also train, they may:
- Lose lean muscle
- Disrupt hormonal balance
- Spike cortisol (stress hormone)
- Under-eat, leading to fatigue and performance dips
She’s especially concerned about female athletes or active women who skip breakfast and train fasted. The risk of under-fueling and long-term damage is high, even if short-term results look “successful.”
Science or experience?
While both Dr. Pelz and Dr. Sims care deeply about women’s health, their approaches are built on very different types of evidence.
- Dr. Mindy Pelz’s work is based primarily on her own clinical experience and thousands of case studies from her community. This real-world insight can be incredibly valuable but her recommendations are not drawn from controlled studies or scientific trials. That means there may be confirmation bias, and not all outcomes are universally replicable.
- Dr. Stacy Sims, on the other hand, builds her conclusions from peer-reviewed research in exercise physiology and female endocrinology. Her recommendations are tested across populations, controlled for variables, and subject to scientific scrutiny.
So, while Dr. Pelz’s approach might feel empowering and may work well for some, it’s important to recognise that her conclusions haven't been scientifically validated. Dr. Sims’ caution, meanwhile, comes from data especially data focused on active women, hormonal function, and muscle preservation.
In short: if you’re looking for advice rooted in science, Dr. Sims holds a stronger evidence-based position.
So… Here’s our take
✅ Both voices matter. Dr. Pelz brings a fresh, empowering lens to women’s health, encouraging more body awareness. Dr. Sims brings the science and a reminder that unlike males, the female body needs consistent nourishment, especially under physical stress.
✅ We wonder whether Dr. Pelz advice for fasting from day 1 of menstruating is actually very intuitive of the female body. As you may have experienced, when women menstruate, we often have more cravings. We usually don’t like to stress the body at this time, and it is especially important to take care of what it is asking for. When we lose blood we also lose iron, it’s important to therefore replenish with iron rich foods. We would therefore say that if you are going to fast, to at least wait until bleeding eases and cravings reduce.
✅ Dr. Sims scientific research shows that muscle mass can be lost when we train fasted. Even if losing weight is the goal, losing muscle mass will reduce metabolism and therefore make any weight-loss results hard to sustain.
✅ With fasting having the potential to disrupt hormone balance and increase cortisol, fasting could cause some women to gain weight.
✅ There’s no one-size-fits-all answer. Some of you may genuinely thrive with light fasting during certain parts of your cycle. Some women report having more energy and increased focus. For those who struggle with over-eating, fasting can be used as a way to reduce calorie intake and put off addictive cravings.
✅ What we care about most at ATTIKA is sustainability, strength, and long-term vitality - not chasing trends or short-term fixes.
So… Should You Fast?
While it may be helpful for some women who feel like they’ve tried everything else, fasting doesn’t need to be the answer.
Instead, we encourage you to start with these foundational steps:
✅ Rebalance your meals. Make sure your breakfast includes enough protein (aim for 25–35g), fibre, and healthy fats to support blood sugar and satiety throughout the day.
✅ Eat earlier in the day. Most women do better when their larger meals are consumed earlier. Think: “front-loading” your energy when your metabolism is more active.
✅ Support your nervous system. Chronic stress, under-recovery, and poor sleep often mimic the symptoms people try to fix with fasting (like cravings, bloating, or stubborn weight). Address those first.
✅ Train smart. If you’re strength training, you need fuel. Skipping meals around your workouts may do more harm than good when it comes to hormone health and muscle preservation.
✅ Track, don’t guess. If you’re unsure what’s working, start tracking. Sleep, hunger, mood, energy, cycle… they’re all data points. And your body is always giving you clues.
If you’ve already dialled in the basics and still feel stuck, especially if you notice patterns of emotional eating, cravings, or low energy, then experimenting with fasting could be a tool. But only if you approach it with care:
👉 Do it in alignment with your cycle
👉 Track your mood, energy, and hunger
And if you’re ever unsure, ask us. We’re here to guide you through all the conflicting information and help you find what works for your unique body.
Because at the end of the day, your health journey should make you feel stronger, not smaller.
