by Tasha Stevens
How to Use Your Cycle to Get Lean
Your 28-day female cycle can help you plan your diet. And the more you use it as a guide, the easier it'll be to lose fat.
Ladies, have you ever noticed that at some times of the month, you feel fit, lean, and athletic and then, without changing a thing, find yourself feeling sluggish and frumpy just a couple of weeks later? You're not alone and science has the answers. In fact, the time of the month absolutely impacts your ability to burn fat.
Your hormones fluctuate throughout the month and this directly impacts your metabolic rate and ability to use fat as a fuel source. So, let's break it down and talk about some strategies.
Understanding Your Cycle
You have four hormone phases you move through each month. During each phase, there are distinct changes in key hormones that influence metabolic rate and fat burn:
- Menstrual Phase (days 1-5): This is when your hormones are at their lowest and your body is shedding excess uterine lining. Due to the loss of blood, your resting metabolic rate (RMR) is higher. Insulin function is lower at this time, making you more sensitive to shifts in blood sugar (1).
- Follicular Phase (days 6-10): As your body is preparing an egg for ovulation, follicle-stimulating hormone (FSH) and estrogen are rising. During this time, your RMR decreases to its lowest point in your cycle (2). Insulin function is higher to effectively allocate energy to ensure your body has what it needs for healthy ovulation.
- Ovulatory Phase (days 11-15): The egg is released from the follicle. Testosterone, luteinizing hormone (LH), and estrogen peak to support this process. Your metabolic rate is lower, but insulin function is high.
- Luteal Phase (days 16-28): Progesterone and estrogen are high to help your body prepare for potential conception. Metabolic rate and RMR are higher to ensure your body has ample energy to support fertilization and implantation. Insulin function is diminished.
Your Fat Burning Phases
It might be easy to read this and think, "A higher metabolic rate in the luteal and menstrual phase means you can burn more fat." But that's not quite the case. Looking at that factor alone fails to account for the interconnected role each hormone plays.
During the follicular and ovulatory phase, your metabolic rate is lower, but due to the rise in estrogen and testosterone, your body's ability and willingness to burn fat is higher. This is because of the role that estrogen and testosterone have on insulin function and carbohydrate metabolism.
Estrogen actions in pancreatic islet β-cells also regulate insulin secretion, nutrient homeostasis, and survival (3). Insulin's role in the body is to respond to the intake of blood sugar and properly allocate blood sugar either to immediate energy use, storage of glycogen in the muscles, or storage of excess blood sugar to fat cells (4).
When insulin is functioning optimally, your body is extremely effective at utilizing this energy and ensuring that blood sugar levels remain stable. When blood sugar is stable, this also regulates cortisol, your stress hormone. When blood sugar is stabilized, your cortisol levels can remain stable, and energy production pathways and fat oxidation pathways function optimally. This means you have more potential to burn fat.
This coupled with the proper cycle-synced progressive overload and training types in your workouts ensures that you're optimizing fat burning.
Compared to your luteal and menstrual phase, sure, your metabolic rate is higher, but your body is not in a "fat loss" mindset, so to speak. Your body is preparing for potential conception (whether you're trying or not).
Progesterone, your "pro-gestation" hormone, spikes to ensure digestion and energy slow to create a safe environment for fertilization and implantation. As a result, insulin function declines dramatically (2). So instead of your body effectively reallocating blood sugar to immediate energy use or glycogen stores, excess remains in the bloodstream for longer and eventually gets allocated to fat cells (4). This can lead to an increased production of fat cells.
Additionally, increased disruptions in blood sugar can lead to spikes in cortisol (5). So chronic disruption of blood sugar in the luteal and menstrual phases can lead to increased stress response and fat storage. Especially if you're under-eating in these phases, which triggers a stress response in the body. This is why you can't confuse a higher metabolic rate with a higher fat-burning potential.
Make Your Cycle Work for Your Goals
Changes to how you time your nutrient intake, carb intake, and workouts can help you "bio-hack" your cycle to get more out of your body's fat-burning capacity.
Follicular & Ovulatory Phase
During these phases, take advantage of your fat-burning capabilities and increased energy. This is the best time to implement a 10-15% total reduction in caloric intake compared to optimal basal metabolic rate (BMR) and activity level can help to increase fat oxidation. Avoid reducing calories too low, which can trigger a stress response. If the stress response is triggered, it can lead to increased fat storage potential.
Your body will increase its use of carbohydrates during workouts due to elevated testosterone and estrogen levels. Your total dietary intake of carbohydrate can vary between 50-60% of your recommended dietary allowance. This increased intake ensures you have proper energy and glycogen stores to fuel higher-intensity and strength workouts.
Due to high insulin function, focus on fast-releasing carbohydrates with higher glycemic indexes, especially pre-workout. Examples include:
- White rice
- Citrus fruits (grapefruit, oranges, mandarin oranges)
- White potatoes
- Corn
- Bananas
- Oats
Due to high insulin function, this is the phase where you can benefit from moderate use of fasted cardio to help improve fat oxidation. Your body is well equipped to handle the stress during this time and will reap more benefits than harm.
Luteal & Menstrual Phase
During these phases, focus on stabilizing blood sugar and minimizing any stress response to avoid counteracting results in the follicular and ovulatory phases.
One critical point: your energy demand is higher during this time. So, you need to listen and respond to this, especially if you want to support optimal hormone balance and fat burn in the next cycle.
This isn't the time to cut calories. Eating at your BMR will give your body what it needs to support optimal function. However, if you've been in a deficit for a prolonged period, you'll likely need to build your way back up to your BMR through a structured reverse diet.
Insulin function is lower, so your body is more sensitive to the blood sugar disruption associated with carb intake. So, try to reduce your intake of carbs to between 40%-45% of daily intake and prioritize increases in protein and healthy fats.
Prioritize complex carbs with a lower glycemic index:
- Sweet potatoes
- Yams
- Quinoa
- Brown rice
- Root vegetables
- Squash
Focusing on quality protein (Buy at Amazon) and fats high in omega 3 fatty acids (Buy at Amazon) will provide the building blocks for hormone production for these phases and prep your body for the upcoming follicular phase.
Due to the lower insulin function, avoid fasted workouts. Also, to help stabilize blood sugar across the day and avoid spikes in cortisol, eat at regular intervals to combat cravings associated with PMS.
Key Takeaways
- Your cycle can be your superpower when it comes to fat burn. You just need to learn how to use it.
- Metabolic rate might be higher in your luteal and menstrual phase, but this doesn't mean your fat-burning capabilities are higher.
- Follicular and ovulatory phases have lower metabolic rates but higher fat-burning potentials.
- While metabolic rate is highest in the luteal and menstrual phase, the risk of increased stress and fat storage is higher. Increased energy intake and adapting carb intake in these phases are proactive steps to help prevent this.
- Varying your calorie and carb intake across your cycle can lead to increased fat burn without increasing the total stress response.
References
- Escalante Pulido JM, Alpizar Salazar M. Changes in insulin sensitivity, secretion and glucose effectiveness during menstrual cycle. Arch Med Res. 1999 Jan-Feb;30(1):19-22. doi: 10.1016/s0188-0128(98)00008-6. Erratum in: Arch Med Res 1999 May-Jun;30(3):265. PMID: 10071420.
- Solomon SJ, Kurzer MS, Calloway DH. Menstrual cycle and basal metabolic rate in women. Am J Clin Nutr. 1982 Oct;36(4):611-6. doi: 10.1093/ajcn/36.4.611. PMID: 7124662.
- Mauvais-Jarvis F, Clegg DJ, Hevener AL. The role of estrogens in control of energy balance and glucose homeostasis. Endocr Rev. 2013 Jun;34(3):309-38. doi: 10.1210/er.2012-1055. Epub 2013 Mar 4. PMID: 23460719; PMCID: PMC3660717.
- NIH study shows how insulin stimulates fat cells to take in glucose. (2010, September 7). National Institutes of Health (NIH).
- Moyer AE, Rodin J, Grilo CM, Cummings N, Larson LM, Rebuffé-Scrive M. Stress-induced cortisol response and fat distribution in women. Obes Res. 1994 May;2(3):255-62. doi: 10.1002/j.1550-8528.1994.tb00055.x. PMID: 16353426.