Decoding Your Cyclical Metabolism And Feeding Your Flow
Learn how to leverage your metabolic pathways throughout your cycle.
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The guidance included in this post is intended for active women participating in some form of regular resistance training and exercise.
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Have you ever wondered why some days it feels like you’re crushing it—a HIIT workout before breakfast, mental clarity during workday meetings, energy left in the tank to get frisky—and on other days even menial tasks can dip you into the red?
Why sometimes you feel satisfied with a raw salad and other times you snack on everything in sight, yet still feel hungry? It is the same reason that your sleep may suffer before your period or you’re sweating more quickly in the follicular phase.
Menstruating women have a cyclical metabolism which includes our 24-hour circadian clock, as well as a longer infradian rhythm dictated by our monthly cycle.
Because our bodies are designed to reproduce, our metabolism operates at a very high efficiency and varies throughout the month, due to our fluctuating hormones.
We can use these changes to our advantage by learning how to eat for our metabolism that will further enhance our body all month long.
Cyclical Metabolism
There are a few key metabolic changes that occur during each cycle with inflection points marked by menstruation and ovulation.
In general, our baseline metabolism is lower from menstruation to ovulation and increases slightly after ovulation.
From a metabolic perspective, the follicular and luteal phases might be split further to capture the many nuanced changes that occur. However for simplicity, the cycle is broken down into three parts below with generalized metabolic conditions.
Low-Hormone Phase: Menstrual and Early Follicular
estrogen ↓ progesterone ↓
Key reproductive hormones—namely progesterone and estrogen—plummet to their lowest levels during the final days of each cycle. It is this drop that signals the release of the uterine lining resulting in your period.
At this time, several metabolic shifts occur that are associated with low-hormone physiology:
Basal metabolic rate slows.Studies have shown that a woman’s resting metabolic rate slows with the onset of her period to its lowest point in the days leading up to ovulation and then begins to climb back up in the latter half of the cycle (1). You burn fewer calories during the follicular phase and can get away with a little less in terms of energy intake.
Carbs are put to quick use.The body is better at metabolizing carbohydrates in the follicular phase when the release of muscle glycogen (energy storage) is not inhibited by estrogen and progesterone (2). Pro tip: you have to eat carbs to take advantage of this metabolic upgrade!
Body temperature decreases and cooling is more efficient. With low progesterone levels in the first half of the cycle, body temperature is slightly lower. This means that you begin sweating at a lower temperature and cooling is more efficient as a result of plasma volume expansion (3) (more fluid in the blood).
Mid-Cycle: Late Follicular and Ovulation
estrogen ↑ progesterone ↓
Characterized by a surge in lutenizing hormone and estrogen hormones, ovulation also brings a slight increase in testosterone. Though short in duration, the ovulatory phase presents a unique window of opportunity where we reap the energy-boosting benefits of estrogen without the catabolic consequences of progesterone.
Estrogen increases the anabolic response. As estrogen climbs and when we see a slight bump in testosterone around ovulation, the body’s muscle building (anabolic) response increases meaning the energy you take in contributes to building and maintaining muscle mass when paired with strength training and exercise.
Enhanced insulin sensitivity before ovulation. Estrogen improves insulin sensitivity5 and as a result, glucose levels are more stable during the late follicular phase when this sex hormone surges in the absence of progesterone. However, with the hormone cocktail that accompanies ovulation, you might experience a shift toward insulin resistance mid-cycle.
More fat is stored during ovulation.
During ovulation, any excess energy consumed is more likely to be stored as fat in response to erratic blood glucose when adipsin levels are elevated (6)—adipsin is a hormone released by fat cells and is thought to regulate fat metabolism.
High-Hormone Phase: Luteal
estrogen ↑ progesterone ↑
As progesterone levels climb mid-luteal phase, the body shifts into resource-sparing mode and favors fat burning for fuel. In addition, baseline functions demand more calories and without a corresponding upgrade in nutrition, you might feel a dip in overall energy levels. Not to mention that the calming effects progesterone can make some menstruators feel tired during this phase.
Basal metabolic rate increases. It’s natural to feel hungrier during your luteal phase, as your body needs an extra 100-300 calories to prepare your body for pregnancy (even if you’re not trying to conceive) or menstruation.
Progesterone increases catabolic response.
With elevated progesterone in the luteal phase, the body shifts into breakdown mode and requires more recovery time. This is when fasting can be detrimental for menstruators particularly during physical activity. Pro tip: have a light snack before you exercise.
Glycogen release is inhibited. The body is more stingy with fuel when both estrogen and progesterone are elevated in this phase, sparing glycogen (2) to store the life-giving nutrients necessary to support pregnancy. It can feel like your digestion slows down, and it’s difficult to make quick use of carbohydrates. Pro tip: favor protein and quality fats as these are the preferred fuel source during the luteal phase.
Insulin sensitivity decreases. Progesterone promotes insulin resistance5 and during the high-hormone luteal phase, blood glucose levels are of greater concern. Being mindful of excess sugar will improve your mood, energy and period.
The body is slower to sweat. Progesterone promotes heat conservation and your body will get hotter before you start to sweat with a slightly elevated basal body temperature. This can contribute to feeling a bit flatlined during exercise.
Note: Progesterone can appear to cause us stress, but it’s one of the good guys! Progesterone helps maintain fluid balance so you don’t retain so much water weight before your period, helps you sleep more deeply before your period, and impacts your mood by feeling calm and balanced.
Feed Your Flow
As we strive to understand our metabolism and how it changes, when we eat and exercise the same way every day focusing solely on calories in vs. calories out, we are likely to be out of balance part of the time.
Here’s how to cycle sync your metabolism:
Low-Hormone Phase
You can get away with less, but resist the temptation to fast. While baseline functions require fewer calories in this phase, operating in a fasted state can be interpreted as a threat to the female body and signal higher levels of cortisol. Higher cortisol can lead to fat storage and estrogen imbalance. The bottom line? You can reduce calorie intake, but fuel your body according to your activity level.
Support healthy flow by replenishing iron, zinc, and magnesium levels during your period. Nosh on nutrient-rich foods including: meat protein, spinach, lentils, oats, cacao nibs, flax seeds, and nuts.
Reach for your favorite anti-inflammatory foods during your period. Cook with ginger and turmeric, sip on green tea, snack on berries, enjoy fatty fish like salmon.
Don’t be afraid of carbohydrates. With higher insulin sensitivity, this is the time to take advantage of quick-acting carbs for energy—particularly before/after higher intensity exercise—when your body prefers this energy source. Pro-Tip: consume your carb-heavy meals earlier in the day to enhance fat-burning mode overnight.
Leverage the first half of the cycle for its muscle-building potential by consuming complete proteins—or supplementing with essential amino acids—to improve muscle-protein synthesis, This the process of repairing muscle tissue after the positive stress induced by exercise. Note: this is a good practice in all phases of your cycle!
Mid-Cycle
Support increased energy levels—largely resulting from elevated estrogen—with quality carbohydrates particularly before and after high intensity exercise.
Pair carbohydrates with high levels of protein and quality fats to support muscle building and adaptation.
Stabilize your blood sugar and avoid spikes during ovulation when your body is more likely to store excess calories as fat. Consume low-glycemic carbs and pair them with complete proteins.
High-Hormone Phase
With less tolerance to carbohydrates, focus on slow-absorbing and low-glycemic foods that boast a high level of satiety. Think quinoa, sprouted grains, vegetables, and low-glycemic berries/fruits.
Don’t skip high-quality essential fats in the luteal phase when you benefit from a higher dose of omega 3s and the body prefers fat as fuel. Healthy fats like avocado, oily fish, olive oil, and nuts can help you fight off the mental fog that sometimes comes with progesterone.
As in the first half of the cycle, pay close attention to the quality of your protein as not all sources are equal. In an effort to combat the catabolic (breakdown) effects of progesterone, make sure you’re getting complete proteins or supplementing with essential amino acids to provide the building blocks your muscles need.
When hormone levels plummet in the days leading up to your period, return to the anti-inflammatory foods of the menstrual phase and combat stress-induced cravings by managing blood sugar with satiating foods that pack high nutritional value in fewer calories. Foods like Greek yogurt, dark chocolate, meat protein, eggs, salmon, and sweet potatoes can fill you up without throwing you out of balance.
Ready for a comprehensive guide on cycle-syncing your metabolism?
The Takeaway
Your metabolism is a finely tuned system that is guided by your thyroid and endless list of hormones. For menstruating women, estrogen and progesterone create an ebb and flow with our cycle and metabolism. It provides unique advantages for us to know how to support our bodies better just by remaining conscious of how we eat and move.
Syncing your food and movement to your cycle can help support your body’s changing energy needs, so you can navigate the metabolic changes with greater ease.
References
Benton, M. J., Hutchins, A. M., & Dawes, J. J. (2020). Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis. PloS one, 15(7), e0236025. https://doi.org/10.1371/journal.pone.0236025
Devries, M. C., Hamadeh, M. J., Phillips, S. M., & Tarnopolsky, M. A. (2006). Menstrual cycle phase and sex influence muscle glycogen utilization and glucose turnover during moderate-intensity endurance exercise. American journal of physiology. Regulatory, integrative and comparative physiology, 291(4), R1120–R1128. https://doi.org/10.1152/ajpregu.00700.2005
Hackney, A. C., Kallman, A. L., & Ağgön, E. (2019). Female sex hormones and the recovery from exercise: Menstrual cycle phase affects responses. Biomedical human kinetics, 11(1), 87–89. https://doi.org/10.2478/bhk-2019-0011
Hui Yan, Wangbao Yang, Fenghua Zhou, Xiaopeng Li, Quan Pan, Zheng Shen, Guichun Han, Annie Newell-Fugate, Yanan Tian, Ravikumar Majeti, Wenshe Liu, Yong Xu, Chaodong Wu, Kimberly Allred, Clinton Allred, Yuxiang Sun, Shaodong Guo; Estrogen Improves Insulin Sensitivity and Suppresses Gluconeogenesis via the Transcription Factor Foxo1. Diabetes 1 February 2019; 68 (2): 291–304. https://doi.org/10.2337/db18-0638
Escalante Pulido, J. M., & Alpizar Salazar, M. (1999). Changes in insulin sensitivity, secretion and glucose effectiveness during menstrual cycle. Archives of medical research, 30(1), 19–22. https://doi.org/10.1016/s0188-0128(98)00008-6
More, M. (2020). Menstrual Cycle, Hormones and Metabolism. https://www.lumen.me/blog/science/menstrual-cycle-hormones-and-metabolism
