The menstrual cycle significantly influences various physiological processes, including dietary energy intake. Recent research, including a comprehensive narrative review by Michaela M. Rogan and Katherine E. Black, sheds light on how energy intake fluctuates during different phases of the menstrual cycle. Understanding these variations is crucial, especially for women engaged in physical activities, as it can inform dietary planning and nutritional support.

The Menstrual Cycle Phases

The menstrual cycle is divided into several phases, each characterized by distinct hormonal environments:

• Early-Follicular Phase: Begins with menstrual bleeding, with low levels of estrogen and progesterone.
• Late-Follicular Phase: Leading up to ovulation, marked by high estrogen and low progesterone levels.
• Ovulatory Phase: Around ovulation, with a peak in estrogen and low progesterone.
• Mid-Luteal Phase: Post-ovulation, characterized by medium estrogen and high progesterone levels.

Energy Intake Across the Phases

Early-Follicular Phase

During the early-follicular phase, energy intake tends to be at its lowest. This phase starts with menstrual bleeding and is characterized by low levels of both estrogen and progesterone. The narrative review by Rogan and Black highlights that several studies report reduced caloric intake during this phase, with some women experiencing decreased appetite. For instance, a study in Brazilian women noted an average intake of 1730 kcal/day during the follicular phase.

Late-Follicular and Ovulatory Phases

As women move into the late-follicular phase, leading up to ovulation, there is a slight increase in energy intake. This phase is marked by a significant rise in estrogen levels while progesterone remains low. Some studies suggest that estrogen might have an appetite-suppressing effect, contributing to the lower energy intake observed during these phases. Research by Roney and Simmons indicates that food intake decreases as estrogen peaks around ovulation.

Mid-Luteal Phase

The mid-luteal phase sees the highest energy intake among the phases of the menstrual cycle. After ovulation, progesterone levels rise significantly, and this hormone is believed to stimulate appetite. The narrative review highlights that many studies report increased caloric intake during this phase, with the average increase ranging from 90 to 529 kcal/day compared to the follicular phase. For instance, Reimer et al found an average increase of 337 kcal/day during the luteal phase.

Macronutrient Intake Variations

While the overall energy intake fluctuates across the menstrual cycle, macronutrient preferences also change, albeit less consistently. Some studies suggest an increased craving for carbohydrates and fats during the luteal phase, likely driven by hormonal changes and their effects on mood and appetite.

The Role of Premenstrual Syndrome (PMS)

Women with PMS often experience more pronounced changes in appetite and food cravings, particularly for high-carbohydrate and high-fat foods, during the luteal phase. Research shows that these women report higher energy intake and more severe food cravings premenstrually compared to those without PMS.

Hormonal Influences on Appetite

Hormonal fluctuations play a crucial role in modulating appetite and energy intake. Estrogen generally suppresses appetite, while progesterone has a stimulatory effect. This hormonal interplay is reflected in the cyclical changes in energy intake observed across the menstrual cycle phases. Additionally, changes in serotonin levels, influenced by hormonal fluctuations, may also affect appetite and mood.

Implications for Female Athletes and Active Women

Understanding these cyclical patterns of energy intake is particularly important for female athletes and active women. During phases of lower energy intake, such as the early-follicular phase, additional nutritional support might be necessary to maintain adequate energy availability. Conversely, during the mid-luteal phase, increased energy intake should be balanced to prevent unnecessary weight gain while ensuring optimal performance and recovery.

Cycle Syncing Diet: Practical Applications

Cycle syncing is an emerging concept that aligns dietary and exercise routines with the phases of the menstrual cycle to optimize health, energy levels, and performance. Based on the findings from the narrative review by Rogan and Black, here are practical applications of a cycle syncing diet:

Early-Follicular Phase (Menstrual Phase)

Characteristics: Low estrogen and progesterone levels, onset of menstrual bleeding.

Dietary Focus:

• Nutrient-Dense Foods: Focus on replenishing iron and zinc lost during menstruation. Incorporate foods like lean red meat, spinach, lentils, and seeds.
• Anti-Inflammatory Foods: Reduce inflammation and discomfort by consuming fatty fish, nuts, seeds, and plenty of fruits and vegetables.
• Hydration: Maintain hydration to combat potential bloating and fluid retention.

Example Meal Plan:

• Breakfast: Oatmeal with berries and flaxseeds.
• Lunch: Spinach and lentil salad with avocado and pumpkin seeds.
• Dinner: Grilled salmon with quinoa and steamed broccoli.

Late-Follicular Phase (Pre-Ovulation Phase)

Characteristics: Rising estrogen levels, preparing for ovulation.

Dietary Focus:

• Lean Proteins and Healthy Fats: Support energy levels and hormone production with lean proteins (chicken, turkey, tofu) and healthy fats (avocado, olive oil).
• Complex Carbohydrates: Provide sustained energy with whole grains, sweet potatoes, and legumes.

Example Meal Plan:

• Breakfast: Greek yogurt with honey, nuts, and seeds.
• Lunch: Quinoa and black bean bowl with mixed greens.
• Dinner: Baked chicken breast with roasted sweet potatoes and asparagus.

Ovulatory Phase

Characteristics: Peak estrogen levels, low progesterone, ovulation.

Dietary Focus:

• Antioxidant-Rich Foods: Support overall health and reduce oxidative stress with berries, citrus fruits, and colorful vegetables.
• Hydrating Foods: Include hydrating foods like cucumbers, watermelon, and leafy greens to support hydration and skin health.

Example Meal Plan:

• Breakfast: Smoothie with spinach, banana, berries, and almond milk.
• Lunch: Chickpea salad with tomatoes, cucumbers, and feta cheese.
• Dinner: Grilled shrimp with a citrus quinoa salad.

Mid-Luteal Phase (Post-Ovulation Phase)

Characteristics: High progesterone levels, increased energy intake.

Dietary Focus:

• High-Fiber Foods: Combat potential bloating and support digestion with high-fiber foods like whole grains, beans, and vegetables.
• Magnesium-Rich Foods: Reduce symptoms of PMS with magnesium-rich foods such as dark chocolate, leafy greens, and nuts.
• Balanced Meals: Ensure balanced meals to maintain energy levels and mood stability.

Example Meal Plan:

• Breakfast: Whole-grain toast with almond butter and banana slices.
• Lunch: Brown rice and black bean bowl with avocado and salsa.
• Dinner: Stuffed bell peppers with quinoa, black beans, and ground turkey.

Practical Tips for Implementing Cycle Syncing Diet

• Track Your Cycle: Use a menstrual cycle tracking app to monitor and predict the phases of your cycle, helping you to plan your diet accordingly.
• Listen to Your Body: Pay attention to your body's signals and adjust your diet based on your energy levels, cravings, and mood changes.
• Plan Ahead: Prepare meals in advance that align with the nutritional needs of each phase to ensure you stay on track.
• Stay Flexible: Remember that every woman's cycle is unique, and flexibility is key. Adjust your diet based on individual responses and specific needs.

By aligning your diet with the phases of your menstrual cycle, you can potentially enhance your overall health, improve energy levels, and support optimal performance in both daily activities and physical exercise. 

Conclusion

The menstrual cycle significantly influences energy intake, with the lowest intake observed during the early-follicular phase and the highest during the mid-luteal phase. These fluctuations are driven by hormonal changes, particularly estrogen and progesterone levels. Recognizing and understanding these patterns can help women better manage their dietary needs throughout the menstrual cycle, ensuring they maintain energy balance and overall well-being. Future research should continue to refine our understanding of these patterns, considering factors such as physical activity levels, psychological influences, and individual variability.