Hormones fluctuate throughout the month depending on the phase of the menstrual cycle.

A typical cycle lasts on average 28 days but can range from 21 to 45 days. Cycles have two clearly distinct phases: the follicular phase (days 1-14) and the luteal phase (days 15-28).

The follicular phase is the time when menstruation occurs. Hormone levels (estrogen, luteinizing hormone (LH), progesterone, and follicle-stimulating hormone (FSH)) are at their lowest at the start of the follicular phase. Estrogen and FSH begin to rise around day 4 or 5 of this phase to prepare the body for ovulation.

At the end of the follicular phase, LH surges due to the increase in estrogen, leading to ovulation. Then the luteal phase begins, and these hormone levels start to decline.

Do Caloric and Macronutrient Needs Change During the Menstrual Cycle?

Consuming adequate calories and macronutrients is essential for athletes to have enough energy for performance and to support proper hormone function. Resting energy expenditure (REE) increases by 2-11.5% during the luteal phase (the second half of the cycle).

This could explain why female athletes may experience a higher appetite toward the end of their cycle. It is always recommended that female athletes listen to their bodies, and this could be a good time to add a balanced snack during the day.

Macronutrients: Carbohydrates During the Menstrual Cycle

Depending on the phase of the menstrual cycle, substrate utilization (i.e., which macronutrient the body uses for fuel) and nutrient requirements may change. Carbohydrate oxidation (using carbohydrates for energy) increases during the follicular phase, while glycogen storage decreases.

Therefore, the follicular phase may better support high-intensity exercise, but female athletes should prioritize consuming carbohydrates before training to ensure they have enough energy for performance.

The Importance of Adequate Fat Intake for Menstrual Function

Adequate dietary fat intake is crucial for supporting hormone production. Fats also serve as a source of energy for low-intensity exercise. Due to the decline in estrogen levels during the luteal phase, carbohydrate oxidation decreases, and the body relies more on fat oxidation, which can better support low-intensity exercise.

Female athletes should aim to consume at least 20% of their total daily calories from fats, prioritizing sources such as avocados, nuts, seeds, olives, oils like avocado and olive oil, and fatty fish.

Intakes lower than this can lead to deficiencies in essential fatty acids and fat-soluble vitamins such as vitamins A, D, E, and K, and increase the risk of low energy availability and menstrual disorders.

Protein During the Menstrual Cycle

Protein plays many important roles in the body, including building and repairing lean muscle mass, supporting bone health, and creating hormones, enzymes, and antibodies. Progesterone and estrogen levels peak during the mid-luteal phase (days 20-24).

During this period, protein oxidation increases, and the concentration of amino acids in plasma decreases, so increasing protein intake during this time may be beneficial. Female athletes should aim for an intake of 1.6 g/kg of protein per day.

Is Supplementation Necessary During the Menstrual Cycle?

Certain nutrient needs increase during menstruation, and deficiencies in micronutrients (vitamins and minerals) can negatively affect overall health, athletic performance, and increase the risk of injury in female athletes.

Female athletes often experience deficiencies in folate, riboflavin, vitamin B12, vitamin D, and iron.

Creatine, omega-3 fatty acids, protein, and caffeine are all supplements that have been shown to be safe and effective for female athletes. It is always recommended to focus on obtaining these nutrients from food whenever possible and to use supplements as needed.

Specific calorie, macronutrient, and supplement needs should still be individualized for the athlete, but the recommendations outlined in this article are likely a universal starting point. If you want a personalized nutrition plan that suits your needs and goals, visit our contact page to sign up for nutritional counseling.