Fitness, Nutrition & the Menstrual Cycle
By Dr. Kathleen Regan, ND When it comes to fitness and nutrition, women have different needs than men. Fitness-based nutrition programs & training schedules have long assumed that men and women are the same. Modern research has taught us that there are important differences between the sexes and understanding our uniqueness can help maximize female performance. Female body composition is naturally higher in fat. The upside is that women use fat as their primary energy source. Women use dietary fats more efficiently than men but tend to lose fat less readily. How is that fair?! Estrogen seems to play a large role in this paradox. It has been shown that estrogen enhances fat use during exercise BUT reduces a woman’s ability to burn fat as energy after eating. Therefore, women may be better off to consume food before exercise but avoid food for 90 minutes after exercise to allow for the body to reach the maximum benefits of exercise induced fat burning. Women’s bodies tend not to burn carbohydrates as fuel until they reach very high levels of exercise intensity (~80-85% max effort). Carbohydrate loading may not be appropriate for the female fitness routine unless she is training at max effort (80-85% VO2max). If a woman is carbohydrate loading during moderate exercise she may not utilize this macronutrient. Worse, these unused carbs are ultimately converted and stored as fat. Therefore, unless a woman is training at a regular high intensity, she will benefit from keeping carbohydrates more moderate or approximately 30% of daily nutrient intake. The menstrual cycle and hormonal fluctuations women experience throughout the month influence their physical response to training as well as their metabolism of carbohydrates and fats. [...]