You need to read this if you skip breakfast

In the world of health and fitness, there’s often a gap when it comes to female-specific exercise and nutrition advice. That’s where Dr. Stacy Sims comes in. As an exercise physiologist and nutrition scientist, Dr. Sims focuses on creating research-backed strategies tailored to women’s bodies, addressing everything from intermittent fasting to hormonal fluctuations and how they impact exercise and nutrition.

Here’s a breakdown of some of her key insights from her research and a recent podcast appearance on the Huberman Lab which I am obsessed with:

Intermittent Fasting, Exercise & Women: A Misalignment?

Intermittent fasting (IF) has become quite the buzzword in the wellness world, with claims of improved metabolism and enhanced fat-burning potential. But for women, especially active women, this trendy eating pattern might be doing more harm than good.

Dr. Sims points out that women are already more metabolically flexible than men due to our higher oxidative muscle fibers. In other words, our bodies are naturally better equipped to use different fuel sources. Adding intermittent fasting into the mix can increase stress levels and elevate cortisol, which can prevent us from reaching higher intensity during workouts. Essentially, our bodies may be lacking the fuel needed to support post-exercise recovery, growth hormone production, and overall hormonal balance.

Rather than fasting for long periods, Dr. Sims suggests timing our food intake in alignment with our body’s needs. For example, fueling up with a bit of protein before a strength session can optimise performance and recovery without pushing the body into a stressed state.

Hormones, Stress, & Women’s Health

Our brains and hormones play a crucial role in how we respond to exercise and nutrition, especially when stress enters the picture. The hypothalamus, a small but mighty part of the brain, regulates hunger, reproductive hormones, and energy balance. For women, this delicate system can be easily disrupted by exercise without adequate fueling, leading to changes in key hormones like thyroid and luteinizing hormone (LH). This disruption can affect everything from our energy levels to our cognitive function.

Dr. Sims encourages women to eat when their bodies are under stress—yes, even after that early morning workout! Eating in alignment with our body’s natural rhythm can help protect our hormone balance, support better brain function, and reduce the risk of thyroid dysfunction.

Fuel for Performance: The Importance of Pre- and Post-Workout Nutrition

Many women may feel hesitant to eat before exercise, especially if they’ve been led to believe that fasted workouts burn more fat. But Dr. Sims emphasises the importance of fueling for training. A small serving of protein before a strength workout, or adding carbs before cardio, can make all the difference. By doing this, you’re signaling to your body that there’s fuel on board, helping to blunt cortisol and optimise your training efforts.

One thing Dr. Sims stresses is that the old calorie-focused mindset doesn’t apply here. The goal isn’t to restrict but to fuel properly to support your body’s needs, particularly when it comes to preventing low energy availability (LEA), which can be a tipping point for endocrine dysfunction. For women, this means aiming for at least 30 calories per kilogram of fat-free mass to keep things running smoothly.

Eating & Training: Tailoring Your Approach to Your Cycle

Understanding your menstrual cycle and how it impacts your appetite, energy, and performance can be a game-changer. Dr. Sims highlights the importance of adjusting your training and nutrition to align with your body’s natural rhythms. For example, during the luteal phase (the week or so before your period), you might need more carbs to support your body’s increased energy demands.

And when it comes to nutrition, she suggests following an 80/20 approach: 80% of your diet should focus on whole, nutrient-dense foods, while the remaining 20% can be the foods that bring you joy and keep life enjoyable. The key is finding balance and listening to your body’s cues, rather than being swayed by external diet culture noise.

Final Thoughts

Dr. Stacy Sims' research serves as a reminder that women’s bodies are not small men’s bodies. We have different needs when it comes to exercise and nutrition, and understanding these needs is essential for optimal health, performance, and longevity. Instead of blindly following trends like intermittent fasting or fasted workouts, women can benefit from listening to their bodies, fueling appropriately, and working with their unique physiology—not against it.

By tuning into your body’s needs and taking a science-backed approach to exercise and nutrition, you can support not just your performance but your overall well-being for the long haul.

You can listen to the full podcast here; Dr. Stacy Sims: Female-Specific Exercise & Nutrition for Health, Performance & Longevity https://open.spotify.com/episode/0C4NGR78gbSSB2JrgkhwFD?si=tvORuvwsS8a4J_gPxCsu6g

Be kind to yourself,

M x