As female athletes transition through peri- and post-menopause, hormonal changes—particularly lower estrogen levels—affect metabolism, insulin sensitivity, and carbohydrate utilization. Estrogen plays a key role in glucose metabolism, fat storage, and insulin sensitivity, so as estrogen declines, the body becomes more prone to insulin resistance and changes in how carbohydrates are processed. Here are some key adjustments peri- and post-menopausal female athletes should consider when managing carbohydrates:

1. Moderate Carbohydrate Intake

• Quality over quantity: Instead of drastically reducing carbohydrate intake, focus on choosing high-quality, low-glycemic carbohydrates such as vegetables, fruits, whole grains, and legumes. These sources cause a slower rise in blood sugar and can help mitigate insulin spikes.
• Smaller, frequent meals: Instead of large, carbohydrate-heavy meals, consume smaller amounts of carbohydrates more frequently throughout the day to avoid blood sugar crashes and insulin spikes.

2. Focus on Timing Around Workouts

• Fueling for exercise: Carbohydrates should be timed around workouts to maximize energy during training and recovery. Pre-workout carbohydrates can provide immediate fuel, while post-workout carbohydrates help replenish glycogen stores.
  • Pre-workout: 20 grams of carbohydrates (combined with protein) can help provide energy for high-intensity workouts.
  • Post-workout: Rapid consumption of 1.2 grams of carbohydrates per kg of body weight, paired with 0.38 grams of protein per kg of body weight within 30–40 minutes after exercise is critical for post-menopausal women. This timing helps optimize glycogen replenishment during the non-insulin dependent phase of glycogen synthesis.

3. Prioritize Carbs Post-Exercise

• After exercise, the body is more sensitive to carbohydrates, even with reduced estrogen levels. This is especially important for glycogen replenishment and recovery.
  • Post-exercise, women should consume at least 1.2 grams of carbs per kg of body weight within 30-40 minutes to take advantage of increased glycogen storage during this period, even with insulin sensitivity changes. This can also help with muscle recovery.

The recommendation that women, especially peri- and post-menopausal athletes, should consume at least 1.2 grams of carbohydrates per kilogram of body weight within 30-40 minutes post-exercise is supported by research that highlights the importance of rapid glycogen replenishment and muscle recovery following exercise.

Here are key research points that support this recommendation:

1. Post-Exercise Glycogen Replenishment

• After intense exercise, muscles are primed to absorb glucose and replenish glycogen stores.
• This window of opportunity—often called the “glycogen synthesis window”—occurs within the first 30-60 minutes post-exercise when muscle cells are more permeable to glucose, even in the presence of insulin sensitivity issues (e.g., in peri- and post-menopausal women).
• Ivy (1998): This foundational review shows that consuming carbohydrates immediately after exercise significantly enhances the rate of glycogen storage compared to delaying intake by several hours.
• It found that carbohydrate ingestion post-exercise should occur quickly to maximize the rate of glycogen replenishment in the early post-exercise phase .

2. Increased Insulin Sensitivity Post-Exercise

• Carbohydrate ingestion post-exercise leads to increased glycogen synthesis in skeletal muscle due to enhanced insulin sensitivity after a workout.
• Insulin-independent glucose transport mechanisms, such as the translocation of glucose transporter 4 (GLUT-4) to the muscle cell surface, allow rapid glucose uptake by muscles.
• Jentjens and Jeukendrup (2003): Research emphasizes that post-exercise glycogen synthesis can be increased when carbohydrates are consumed immediately after exercise, independent of insulin action in the initial phase of recovery.
• This is particularly beneficial for women experiencing insulin sensitivity changes due to hormonal shifts .

3. Carbohydrate Recommendations for Glycogen Replenishment

• The International Society of Sports Nutrition (ISSN) recommends consuming 1.2 grams of carbohydrates per kilogram of body weight within the first 30 minutes post-exercise to optimize glycogen resynthesis, especially in endurance athletes.
• This recommendation is grounded in research that demonstrates how glycogen resynthesis rates are maximized when sufficient carbohydrates are consumed immediately after exercise .
• For peri- and post-menopausal women, timely post-exercise carbohydrate intake is essential to capitalize on the short window where glucose uptake can occur more rapidly without as much reliance on insulin.

4. Impact on Muscle Recovery

• Hawley et al. (1997) demonstrated that rapid carbohydrate intake post-exercise enhances not only glycogen replenishment but also muscle recovery.
• By consuming sufficient carbohydrates post-exercise, athletes reduce muscle soreness and improve subsequent performance in later sessions, even when insulin sensitivity is compromised .
• Carbohydrates are necessary for providing the energy needed for recovery and muscle protein synthesis.
• When paired with protein, as recommended (0.38g/kg), they optimize both glycogen replenishment and muscle recovery.

5. Carbohydrate Recommendations for Women

• Stacy Sims (2022) and other researchers emphasize that female athletes, particularly those in peri- and post-menopausal phases, should focus on rapid carbohydrate intake post-exercise.
• Due to hormonal fluctuations, including decreased estrogen levels that impact insulin sensitivity and carbohydrate metabolism, timely carbohydrate consumption can mitigate these challenges and optimize glycogen storage and recovery .

Conclusion:

• The 1.2 grams of carbohydrates per kilogram of body weight within 30-40 minutes post-exercise recommendation is based on the enhanced muscle glycogen resynthesis and muscle recovery that occurs during the critical post-exercise window.
• Studies consistently show that rapid carbohydrate ingestion, particularly in female athletes experiencing hormonal changes, can offset reduced insulin sensitivity and promote better recovery and adaptation to training.

By capitalizing on this period, peri- and post-menopausal women can support their performance, recovery, and overall metabolic health.

4. Adjust Carb Intake Based on Exercise Intensity

• Higher-intensity days: Maintain a moderate to higher carbohydrate intake on days of intense training, focusing on carb sources that stabilize blood sugar, such as fruits and whole grains.
• Low-intensity or rest days: Reduce carbohydrate intake on lower-intensity or rest days to match reduced energy expenditure, favoring fibrous vegetables and other low-glycemic carb sources.

5. Support Insulin Sensitivity

• Incorporate healthy fats: Adding healthy fats (like avocado, nuts, and olive oil) to meals can slow carbohydrate absorption and improve insulin sensitivity.
• Lean protein: Combine carbohydrates with lean proteins (such as fish, chicken, or plant-based proteins) to improve satiety and stabilize blood sugar levels.
• Exercise: Regular resistance training can improve insulin sensitivity and help balance the effects of declining estrogen.

6. Consider Lower-Carb Periodization

• Some peri- and post-menopausal athletes may benefit from a cyclical or periodized carbohydrate approach, where they consume fewer carbohydrates on rest days and more on high-intensity or endurance training days.
• This helps manage blood sugar levels and supports energy needs based on physical activity.

7. Include More Fiber

• Focus on fiber-rich carbohydrates, which help regulate blood sugar levels, improve digestion, and enhance satiety. Foods like leafy greens, beans, lentils, and whole grains can help manage insulin resistance.

Summary of Adjustments for Peri- and Post-Menopausal Athletes:

• Quality carbs: Prioritize low-glycemic, fiber-rich carbs like vegetables, fruits, and whole grains.
• Timing: Concentrate carb intake around workouts (pre- and post-exercise), especially post-workout.
• Portion control: Smaller, frequent carbohydrate portions can help regulate blood sugar levels.
• Post-exercise carbs: Ensure rapid post-exercise carb intake (1.2 grams/kg) with protein to support glycogen replenishment and recovery.
• Balance with protein and fats: Combine carbs with lean proteins and healthy fats to improve insulin sensitivity and maintain muscle mass.

By adjusting carbohydrate intake based on exercise intensity, hormonal changes, and individual insulin sensitivity, peri- and post-menopausal female athletes can continue to fuel their performance while maintaining metabolic health.

What does Dr. Mikki suggest for fueling the aging female athlete?

Ask Coach Debbie Potts for a personalized program to follow!

Rabbit Hole:  How much glucose is required by the body at rest?

The human body tightly regulates blood glucose levels to ensure a steady supply of energy, particularly for the brain, which relies heavily on glucose for function.

• Normal blood glucose levels in a healthy person typically range between 70 to 100 mg/dL (milligrams per deciliter) when fasting.
• After eating, blood glucose levels can rise temporarily but usually stay below 140 mg/dL.

To express it in more practical terms:

• The average adult has about 4-5 grams of glucose circulating in the bloodstream at any given time.

• This is roughly equivalent to just about one teaspoon of sugar in total.

To match the 4-5 grams of glucose that the average adult has circulating in their bloodstream at any given time, let’s identify carbohydrate sources and servings that supply a similar amount.

Since 1 gram of carbohydrate provides about 1 gram of glucose after digestion (depending on the type of carbohydrate), you would need about 4-5 grams of carbohydrate to replenish or match the glucose levels in the bloodstream. Here’s a breakdown of common carbohydrate sources that provide approximately 4-5 grams of glucose:

Carbohydrate Sources Equivalent to 4-5 grams of Glucose:

1. Table Sugar (Sucrose):
   • 1 teaspoon of table sugar contains approximately 4 grams of carbohydrates (which is nearly all glucose once digested).
   • This is almost a direct match for the 4-5 grams of glucose circulating in the bloodstream.
2. Honey:
   • 1 teaspoon of honey contains roughly 5.8 grams of carbohydrates, mostly in the form of glucose and fructose.
   • This is slightly above the bloodstream equivalent but quite close.
3. Banana:
   • A slice of banana (about 1/10th of a medium banana) provides approximately 4-5 grams of carbohydrates.
   • This would deliver a similar amount of glucose after digestion.
4. White Bread:
   • A small bite or quarter slice of white bread (about 1/6th of a slice) contains approximately 4-5 grams of carbohydrates.
   • White bread contains fast-digesting carbohydrates that are quickly converted to glucose.
5. Apple:
   • A thin slice of apple (about 1/8th of a medium apple) provides 4-5 grams of carbohydrates.
   • Most of the carbohydrates in an apple come from sugars, including glucose.
6. Orange Juice:
   • A small sip (about 20-25 mL) of orange juice provides about 4-5 grams of carbohydrates.
   • This is mainly in the form of simple sugars that are rapidly converted to glucose.

Explanation:

• The small amount of 4-5 grams of glucose circulating in the bloodstream is continuously replenished by dietary sources like those listed above, as well as through internal processes like gluconeogenesis (glucose production by the liver) and glycogen breakdown.
• These sources provide the body with the necessary fuel to maintain blood glucose levels, support brain function, and ensure overall metabolic stability.
• Maintaining stable blood glucose levels is essential, and even small amounts of dietary carbohydrates, such as 1 teaspoon of sugar or honey, can significantly impact glucose levels, particularly before or during physical activity.
• This small but critical amount of glucose is continuously replenished through dietary carbohydrates, gluconeogenesis (production of glucose by the liver), and glycogen breakdown in the liver and muscles. Maintaining these glucose levels is essential for overall metabolic stability.

To match the 4-5 grams of glucose that the average adult has circulating in their bloodstream at any given time, let’s identify carbohydrate sources and servings that supply a similar amount.

Aging females may need to slightly increase their blood glucose levels before exercise to enhance fat oxidation, but it’s more about providing just enough glucose to prevent the body from going into a stressed, glucose-depleted state.

Dr. Stacy Sims emphasizes that aging females should optimize their pre-workout nutrition for the specific goal of fat oxidation and energy balance rather than overloading with carbohydrates.

Why Small Amounts of Carbohydrates May Help Fat Oxidation in Aging Females:

1. Reduced Glycogen Stores and Metabolic Shifts with Age:
   • As women age, hormonal changes—especially the decline in estrogen and progesterone during perimenopause and menopause—can reduce the body’s efficiency in accessing stored glycogen and fat. Estrogen helps promote fat oxidation, and with reduced levels, the body may rely more on carbohydrates.
   • Consuming a small amount of carbohydrates (15-30 grams) before exercise can help spare muscle glycogen, maintain blood glucose levels, and prevent early fatigue. This ensures that the body has enough immediate energy to support moderate-intensity exercise, allowing fat oxidation to kick in once the workout progresses.
2. Glucose for Performance and Metabolic Flexibility:
   • The body requires a balance between glucose and fat for fuel, especially during higher-intensity or longer workouts. If blood glucose levels are too low, the body prioritizes using glucose for critical functions (like brain activity) and may struggle to efficiently tap into fat stores.
   • By consuming a small, controlled amount of carbohydrates before exercise, aging females can stabilize their blood glucose levels, ensuring the body has sufficient energy for the initial stages of exercise. This promotes metabolic flexibility, allowing the body to gradually transition to burning fat as exercise intensity moderates.
3. Avoiding Stress Responses:
   • Low blood glucose levels during exercise can trigger the release of stress hormones like cortisol, which promotes the breakdown of protein (muscle tissue) to create glucose. This can hinder fat oxidation and encourage fat storage, particularly in the abdominal area.
   • A small carbohydrate boost before exercise helps avoid this stress response, maintaining energy balance without excessively elevating blood glucose.

The Right Amount of Carbohydrates:

• 15-30 grams of carbohydrates (as suggested by Dr. Stacy Sims) can be sufficient to support the initial energy needs of aging females during exercise without blunting fat oxidation. This amount is small enough to prevent a significant insulin spike, which would hinder fat metabolism, but large enough to ensure adequate energy availability.

Timing and Type of Carbohydrates:

• Simple, fast-digesting carbohydrates (like a banana, a small serving of oatmeal, or a piece of toast) are ideal for providing immediate energy without causing a large blood sugar spike.
• Consuming these carbohydrates 15-30 minutes before exercise ensures that blood glucose levels are adequately elevated for the workout’s early phases.

While aging females don’t need to drastically increase blood glucose levels before exercise to burn fat, a small amount of carbohydrates (15-30 grams) can help stabilize glucose levels and provide an immediate energy source. This ensures that the body can access fat stores more efficiently as the workout progresses, improving overall fat oxidation and preventing stress responses that could hinder fat metabolism.

According to Dr. Stacy Sims’ research, women’s metabolism differs from men’s, especially in how they utilize glucose and fat during exercise. Dr. Sims highlights several factors that influence how women burn fat during workouts, and offers specific strategies to optimize fat metabolism in females.

Key Insights from Dr. Stacy Sims’ Research on Fat Metabolism in Females:

1. Hormonal Influence:
   • Estrogen and Progesterone: In the menstrual cycle, elevated estrogen levels during the luteal phase (second half) promote fat oxidation, while progesterone increases carbohydrate utilization. This hormonal interplay means that women may be more reliant on fat for fuel during low to moderate-intensity exercise, but when glucose stores are used, they need specific strategies to optimize fat metabolism.
2. Pre-workout Fueling:
   • Dr. Sims advocates for tailored fueling for women based on their workout intensity and hormonal cycle. For example, she suggests a small amount of carbohydrates (15-30 grams) before moderate-to-high-intensity workouts to ensure glucose is available initially, which then allows for better fat metabolism as the workout progresses.
   • For lower-intensity sessions (fat-burning zone), women can opt for a lighter meal or fasted training (if tolerated), which encourages the body to tap into fat stores.
3. Training in a Fasted State:
   • While Dr. Sims cautions against excessive fasted training for women due to its potential impact on hormone balance and stress levels, occasional fasted low-intensity training can improve fat metabolism. However, she emphasizes that fasted training should be done in the follicular phase (first half of the menstrual cycle) when hormone levels support better recovery and fat oxidation.
4. Protein and Fat Timing:
   • Sims encourages women to prioritize protein intake alongside their workouts to maintain muscle mass and metabolic efficiency. She suggests post-workout protein within 45 minutes to prevent muscle breakdown and improve recovery, which indirectly enhances fat metabolism over time.
   • For sustained fat-burning, combining healthy fats and protein before lower-intensity sessions may help enhance the body’s ability to rely on fat stores.
5. Periodization of Training and Nutrition:
   • Dr. Sims advises aligning training and nutrition with the phases of the menstrual cycle to optimize fat burning. For example, during the follicular phase, when estrogen is higher, women can focus on strength and higher-intensity workouts and use carbs more effectively. In contrast, during the luteal phase, when the body is naturally primed to burn fat, lower-intensity, steady-state exercise can help women maximize fat metabolism.
6. Managing Stress Hormones:
   • Chronic high-intensity exercise can elevate cortisol, which promotes fat storage, particularly around the abdomen. Sims recommends that women balance their training with adequate recovery and stress management strategies to avoid over-reliance on glucose and encourage fat metabolism.

Practical Tips for Enhancing Fat Metabolism in Females (from Dr. Stacy Sims’ insights):

• Pre-workout: Include a small amount of carbohydrates (~15-30 grams) to prevent glucose depletion and aid in fat-burning transitions.
• During workout: For endurance sessions, focus on steady-state cardio during the luteal phase to promote fat utilization.
• Post-workout: Prioritize a mix of protein (20-40 grams depending on the training intensity) and carbohydrates to replenish glycogen and support recovery without triggering excessive fat storage.
• Overall Nutrition: Maintain a balanced diet with healthy fats (avocado, nuts, olive oil) and proteins to enhance fat-burning potential throughout the day.

By considering menstrual phases, fuel timing, and intensity, women can better access fat stores and optimize their metabolism for long-term energy use.

The recommendation by Dr. Stacy Sims to consume a small amount of carbohydrates (15-30 grams) before moderate-to-high-intensity workouts for females is rooted in the physiological need for glucose to maintain energy levels and support fat metabolism.

Why Pre-Workout Carbohydrates are Important… or are they?  Intensity?

1. Low Circulating Glucose Levels: The body maintains about 4-5 grams of glucose in the bloodstream at any given time, which is equivalent to roughly one teaspoon of sugar. This small amount is crucial for immediate energy needs, especially for high-demand organs like the brain. However, this glucose reserve is limited and quickly depleted during moderate-to-high-intensity exercise.
2. Glycogen and Glucose Depletion: During exercise, particularly at higher intensities, the body prefers glucose as a quick, easily accessible source of energy. Initially, the body uses glucose from the bloodstream and glycogen (stored glucose) from the muscles and liver to fuel these activities. Without an adequate supply of glucose, the body may not perform optimally and could begin to break down muscle tissue or struggle to access fat efficiently for fuel, leading to fatigue and reduced performance.
3. Supporting Fat Metabolism: While the body uses both glucose and fat as fuel sources during exercise, accessing fat for energy is a slower process compared to using glucose. By consuming a small amount of carbohydrates pre-workout (15-30 grams), you provide an immediate source of glucose, which:
   • Helps preserve the limited glucose circulating in the bloodstream.
   • Prevents a rapid drop in blood sugar levels during the initial stages of exercise, when the body is still warming up and adjusting to the intensity.
   • Ensures that muscle glycogen (glucose storage) is spared, so you have a buffer of energy as the workout progresses, allowing for a smoother transition to fat-burning once the body settles into a steady state.
4. How This Enhances Fat Metabolism: If your glucose needs are met initially with a small carbohydrate intake, your body can avoid stress signals (like the release of cortisol) that would otherwise trigger the breakdown of muscle tissue for energy. When glucose is available in the early phases of exercise, the body can shift toward fat metabolism more efficiently after the first 20-30 minutes of the workout, when aerobic (fat-burning) systems start to dominate.
5. Preventing Over-Reliance on Glycogen: By taking in a small amount of carbohydrates, you’re preventing excessive reliance on stored glycogen from the start of your workout. Glycogen stores are limited, and once they are depleted, performance can suffer significantly. Having this small glucose boost allows for a gradual depletion of glycogen, supporting energy availability over the course of the workout and enabling better fat oxidation as you continue.

Connection Between Blood Glucose Levels and Pre-Workout Carbohydrate Intake:

• Blood Glucose Stability: Since the body only has 4-5 grams of glucose circulating at rest, intense exercise can quickly draw down this supply. Without sufficient glucose, the body will prioritize keeping blood sugar levels stable, potentially limiting your ability to sustain a high level of performance. The 15-30 grams of pre-workout carbohydrates (equivalent to about 1 to 2 tablespoons of honey or a small banana) provide just enough glucose to support this early energy demand without spiking blood sugar excessively.
• Metabolic Flexibility: Consuming a small amount of carbohydrates helps maintain blood glucose stability, so the body can transition more seamlessly from burning glucose to burning fat as the workout progresses. Without this, the body may struggle to access fat efficiently or resort to breaking down protein (muscle) to produce glucose, which is not ideal for performance or fat metabolism.

Summary:

Consuming 15-30 grams of carbohydrates pre-workout ensures that the body has an initial source of glucose available during the high-energy demand at the start of exercise, preserving limited blood glucose levels (4-5 grams) and allowing for a smoother transition to fat metabolism later in the workout. This strategy optimizes energy use, prevents early fatigue, and enhances the body’s ability to burn fat, especially during longer or moderate-intensity workouts.