Dr. Sims' Core Philosophy: Women Are Not Small Men
Dr. Stacy Sims is a prominent exercise physiologist and nutrition scientist whose work is built on the principle that women's physiological needs differ significantly from men's. This applies profoundly to pre-workout fueling. While the 'men are better off fasted' argument circulates in some circles, Sims has clearly stated that this approach is detrimental to women's bodies. Fasted training can lead to higher cortisol levels, which can hinder fat metabolism, impair muscle building, and disrupt hormonal function. Therefore, she advocates for a pre-workout snack to signal to the body that fuel is incoming, which in turn blunts the stress response and supports optimal training adaptations.
Fueling for Different Workouts
Dr. Sims' recommendations are not one-size-fits-all but are tailored to the type of exercise you are performing. This customized approach ensures you have the right kind of fuel for the specific demands of your training session.
Pre-Strength Training Fuel
For strength training, the primary goal is to provide amino acids to signal muscle protein synthesis, not just to supply energy for the workout itself.
- The recommendation: About 15 grams of protein 30-60 minutes before training.
- Why it works: This small dose of protein gets amino acids into your system, which signals the hypothalamus in the brain that nutrition is available. This helps to minimize muscle breakdown during the session and primes the body for better recovery afterwards.
Pre-Cardio Training Fuel
For moderate- to high-intensity cardiovascular workouts, the body requires both protein and carbohydrates to maintain blood sugar levels and sustain energy.
- The recommendation: A combination of 15 grams of protein and 30 grams of carbohydrates, consumed 30-60 minutes before your workout.
- Why it works: The carbohydrates provide the quick-acting glucose your muscles need for endurance, while the protein helps preserve muscle mass and keeps your metabolism elevated post-exercise.
Timing Is Key: The Importance of a Small, Timed Snack
Dr. Sims debunks the myth that a large meal is necessary before a workout. Instead, she promotes the idea of a small, easily digestible snack taken closer to the training session. This is particularly important for early morning workouts, where many women tend to train fasted. Some examples include:
- A small protein shake with oats.
- Half a banana with a tablespoon of peanut butter.
- Greek yogurt with a few berries.
- A handful of pretzels or a rice cake with jam.
Hydration Is Non-Negotiable
Hydration is an often-overlooked component of pre-workout preparation. Sims highlights that women have a smaller fluid reserve and can lose more sodium during exercise than men, especially during the luteal phase of the menstrual cycle. She recommends a specific hydration strategy:
- Before your workout: About an hour before, drink 500ml (2 cups) of water with a small amount of added electrolytes. A homemade version is 1 tsp of maple syrup and 1/16 tsp of salt in 500ml water.
- During longer sessions: Continue sipping this solution, potentially using a timer to remind yourself to drink every 15-20 minutes.
Comparison Table: Strength vs. Cardio Pre-Fueling
| Aspect | Strength Training | Cardio-Based Training (up to 1 hour) |
|---|---|---|
| Primary Nutrient Focus | Protein for amino acid signaling | Carbohydrates for fuel, with protein support |
| Macronutrient Ratio | Approx. 15g protein | Approx. 15g protein + 30g carbs |
| Suggested Snack Examples | Greek yogurt, protein shake, eggs | Banana with nut butter, oatmeal with protein powder |
| Timing Window | 30-60 minutes before | 30-60 minutes before |
Conclusion
Dr. Stacy Sims’s approach to pre-workout fueling for women is nuanced and effective. By moving away from a one-size-fits-all model and considering female-specific physiology, she emphasizes the importance of a fed state to manage cortisol and improve performance. Whether your goal is to build strength or boost endurance, a small, strategically timed snack of protein and/or carbohydrates, along with proper hydration, is the key to unlocking your best performance and recovery. Remember, fueling smart is about working with your body, not against it.
For more in-depth information, Dr. Sims' book ROAR offers comprehensive guidance on female-specific exercise and nutrition.
