menstrual cycle keto



Ladies, have you ever found having increased hunger levels or carb cravings right before you start your period? Natural fluctuations in hormones cause changes in metabolism, energy utilization, and hunger/cravings. Understanding these hormonal changes during menstruation can help you plan for success and optimize the ketogenic diet.

 

What is the Menstrual Cycle?

The menstrual cycle is an (approximately) 28-day cycle that a woman goes through repetitively from the time of menarche (puberty) until menopause.* This cycle is characterized by the shedding of the endometrial lining of the uterus (vaginal bleeding/period), followed by the release on an egg (ovulation), followed by the building back up of the uterine lining.  These processes are regulated by specific hormones that cyclically wax and wane.

menstrual cycle phases

What Happens During the Menstrual Cycle?

The menstrual cycle is regulated by four key hormones: estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH); these hormones are under regulation by gonadotropin-releasing hormone (GnRH). GnRH is a hormone secreted by the hypothalamus and acts on the anterior pituitary gland to release LH and FSH.

The menstrual cycle can be subdivided by the uterine or ovulatory cycle.

(These are overlapping cycles that occur simultaneously, they are just named different to describe the action occurring.)

The Ovarian Cycle:

  • Follicular phase: days 1-13
  • Ovulation: day 14
  • Luteal phase: days 15-28

The Uterine Cycle




  • Menses: days 1-5
  • Proliferative phase: 6-14
  • Secretory phase: days 15-28

The follicular phase begins with the menses and ends with ovulation. For the first (approximately) five days, the uterine lining is shedding. LH and progesterone levels are low. FSH is released by the anterior pituitary gland and acts to stimulates a follicle (a sac that contains an egg within the ovary).

LH acts on the follicle to secrete estrogen. This is considered the ovulatory phase. A surge of LH from the anterior pituitary gland acts on the follicle causing ovulation (the release of the egg). The eggs travel down the fallopian tube into the uterus. It is during this time that if sperm is present, the egg may be fertilized and implant into the uterine lining, leading to pregnancy.

The ruptured follicle is known as the corpus luteum and begins to release estrogen and progesterone. Progesterone acts to build back up the uterine lining and increase blood vessels in case of implantation of a fertilized egg. During the luteal/secretory phases, the corpus luteum shrinks and dies, and progesterone production decreases. This decrease in progesterone leads to the restarting of the cycle with the start of the period.

hormone levels

Dietary/Body Composition Changes during Menstruation

So how do these changes in hormone levels affect your nutritional needs? They can actually have a substantial impact on your hunger levels, caloric needs, carb or fat utilization, and athletic performance. Below are some impacts these hormonal changes have on your body.

Menses/ Follicular Phase:

  • Decrease in hunger
  • Increased insulin sensitivity
  • Increased glucose/carb utilization
  • Increased power output (good time for strength training or HIIT in the gym)

Luteal Phase

  • Increased fat utilization
  • Increased hunger (increased cravings and hunger is a good indicator that you’re about to start your period)
  • Decreased strength and power output (good time for low-intensity cardio or de-loading)

 

Dietary Recommendations

Since carbohydrate utilization is increased during the menses / follicular phase, a carb-up is recommended. This will increase energy levels and provide fuel for the body. After ovulation, fat utilization is increased and carb intake should go back to normal. Caloric expenditure typically increases during this phase, so try increasing fat or protein intake to combat hunger.

 

Tips for Success

  • If you increase carbohydrates to a reasonable amount (around 30 to 50g) during your menses but find you’re getting kicked out of ketosis, try high-intensity interval training. Cramps, bloating, and general discomfort may make HIIT seem like the worst thing you could possibly do on your period, but you are actually strongest during this phase. HIIT training will take advantage of this increased power and help deplete glycogen stores.
  • Cravings and hunger typically peak right before your menses. Keep low-carb treats, like fat bombs, around to reduce temptation from non-keto foods.
  • Reduce sugar alcohol, spicy, and salty food intake during your menses to help limit bloating.
  • Eat foods rich in iron during your follicular to supplement the iron you are losing. Examples of these foods include meats, spinach, seeds, and dark chocolate.
  • Eat foods rich in magnesium during the last week of your luteal phase to help combat upcoming PMS symptoms (headaches, cramping, and fatigue). Examples of these foods include avocados, spinach, almonds, and dark chocolate.

*Unless there is an underlying/pre-existing condition that affects menstruation.

 

Resources

Frisen, L. et al. Effects on power, strength and lean body mass of menstrual/oral contraceptive cycle based resistance training. Journal of Sports Medicine and Physiology. (2016)

Hashimoto H, Ishijima T, Hayashida H, Suzuki K, Higuchi M. Menstrual cycle phase and carbohydrate ingestion alter immune response following endurance exercise and high intensity time trial performance test under hot conditions. J Int Soc Sports Nutr. 2014;11:39. Published 2014 Aug 12.

Hawkins SM, Matzuk MM. The menstrual cycle: basic biology. Ann N Y Acad Sci. 2008;1135:10–18.

Reed BG, Carr BR. The Normal Menstrual Cycle and the Control of Ovulation. 2018 Aug 5. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-.

Sung, E., et al. Effects of follicular versus luteal phase-based training in young women. SpringerPlus. 2014.

Thiyagarajan DK, Basit H, Jeanmonod R. Physiology, Menstrual Cycle. [Updated 2019 Apr 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-.

Veldhuijzen DS, Keaser ML, Traub DS, Zhuo J, Gullapalli RP, Greenspan JD. The role of circulating sex hormones in menstrual cycle-dependent modulation of pain-related brain activation. Pain. 2013;154(4):548–559.




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