There is no robust data supporting the need to alter training based on the phase of the menstrual cycle. Women are not less capable during their period. Training should be adjusted based on subjective feelings (fatigue, symptoms) on a given day, not a predetermined hormonal calendar.

Focusing on building muscle is crucial for long-term health, particularly for women entering perimenopause. Muscle helps regulate blood sugar, reduces inflammation, and protects against osteoporosis, dementia, and heart disease, making it a vital health indicator.

For optimal hormonal health, women should not maintain the same diet and exercise routine all month. The first 10-15 days of the menstrual cycle, when estrogen is dominant, is the ideal time for more intense workouts, longer fasts, and low-carb diets.

Most people have sex at night when hormonal profiles are misaligned for intimacy (low testosterone, high melatonin). In the morning, key hormones like testosterone and cortisol are high while melatonin is low, leading to biologically superior performance and connection.

Female metabolism fluctuates significantly with the ovarian cycle. During the first (follicular) phase, women are highly efficient fat-burners and enter ketosis faster than men. However, in the second (luteal) phase, high progesterone levels act as a powerful hunger hormone, making low-carb diets more challenging.

Within the wide, normal range of testosterone for both men and women, hormone levels are not predictive of one's ability to gain muscle. Only supra-physiological levels, such as those from anabolic steroids, create a significant, predictable advantage in muscle growth.

Contrary to popular belief, women's bodies contain substantially more total testosterone than estradiol. This misunderstanding arises because tests use different units (nanograms vs. picograms) or focus only on "free" testosterone, understating its overall prevalence and importance.

Fasting significantly increases natural growth hormone production. By scheduling resistance training towards the end of a fasting window—the peak of the fast—one can leverage this hormonal advantage to better retain and potentially build muscle mass.

In the final phase of the menstrual cycle (approx. day 20 onward), the hormone progesterone rises. Progesterone is sensitive to stress and requires higher glucose levels. This is a time for women to reduce fasting, slow down workouts, and incorporate more healthy carbs, not push through with intense routines.