As a personal trainer, hormonal health seems to be all the rage these days, with everyone harping on about cortisol and insulin and their influence upon your body’s (or your clients) ability to achieve maximal fat loss. Now female fat loss and male fat loss are often two different things!
We know our hormones play a role in determining our body composition. We also know that females have more fluctuations in their hormones than men and that they are more influenced by these changes.
Attention personal trainers!
It is important that you understand from the outset that you are dealing with a completely different beast when dealing with a female client, especially with general populations when it comes to the goal of female fat loss. In this article, we are going explore the female reproductive cycle and it’s influence on female fat loss through the following:
- Anatomy and physiology of the female reproductive system
- Key hormones in each stage, and how this can influence your athlete
- How we can best adapt our training and nutrition around these factors to optimize fat loss, even when our hormones seem to be working against us.
- ANATOMY & PHYSIOLOGY OF THE FEMALE REPRODUCTIVE SYSTEM
Women are not just smaller, more aesthetically pleasing men – they are separate creatures, with a visibly different anatomy, and therefore physiology and hormonal profile – which inevitably leads to drastic differences in how their bodies respond to training, and their nutrient requirements. To understand how to manipulate and control these variables to optimize female fat loss, we first need to understand what is going on…
So, we’re taking a little journey back to 8th grade P.E class boys and girls!
Physiology of the Female Reproductive System
- Vulva: The vulva is the collective name for the external genitalia – specifically the mons veneris, labia majora, vestibule, perineum and clitoris.
- Vagina: The vagina is the passage from the external genitalia to the internal genitalia. It extends from the vulva to the cervix, is the primary organ responsible for sexual intercourse, provides a passage for semen to travel, as well as a canal from which menstrual fluids can pass and babies are birthed.
- Cervix: The cervix connects the uterus to the vagina, and is located at the lower part of the uterus. It acts as a barrier between the vagina and uterus, controlling when and which substances can pass into or out of the uterus. Its’ walls produce a thick mucus which acts to ‘plug’ the cervix. Around ovulation, this mucus membrane becomes thinner to allow the passage of sperm to enter the uterus. In the event of pregnancy, this mucus becomes thick to protect the developing embryo during gestation.
- Uterus: The uterus is the hollow, muscular organ at the center of the system. Its’ primary role is to accept a fertilized ovum and to nourish the developing embryo as it develops into a foetus and all the way through the gestation period until childbirth, when the thick muscular wall of the uterus produces the strong contractions known as labour. Upon conception, the uterus accepts and implants the fertilised egg within the cushy endometrial wall, from which the fetus derives nourishment from blood vessels which develop exclusively for this purpose.
- Endometrium: The endometrium refers to the epithelial layer of the uterus, along with its’ mucus membrane. This is where the fertilized ovum will be implanted should pregnancy to occur. This layer grows thicker with blood and blood vessels approaching ovulation, ready to accept a fertilized ovum. If this does not occur, this layer will shed forming a period.
- Fallopian Tube: The fallopian tubes are muscular tubes extending from and connecting the uterus to the ovaries. They act to nourish the developing ova, and help to transport the ripe ovum to the uterus.
- Ovaries: The ovaries are a pair of small almond-shaped glands located to the upper left and right of the uterus. They produce the ova as well as the female sex hormones, such as Estrogen and Progesterone. Once a female has reached puberty, the ovaries will release a single mature ovum once per month, usually taking turns– this process is called Ovulation. This process continues every month until Menopause.
2. KEY HORMONES IN EACH STAGE, AND HOW THEY AFFECT YOUR CLIENT
The female reproductive cycle is differentiated into two parts:
- The Follicular Phase, which commences on Day 1 of Menses, (the start of her period) and lasts roughly 10-14 days, or until Ovulation occurs. This phase is characterized by the ovaries creating and then maturing a follicle to produce an ovum (egg).
- The Luteal Phase is the second half of the cycle. Post Ovulation the follicle temporarily become a gland, known as the Corpus Luteum, which produces and secretes the hormone Progesterone to ‘hold’ the Endometrial Lining to the wall of the Uterus for implantation should the egg become fertilized.
Hormones of the Female Reproductive Cycle
The ovaries secrete estrogen during the Follicular phase of the cycle. Estrogen is the primary female reproductive hormone, and is also responsible for a female’s development during puberty. Estrogen is also secreted in small amounts by the adrenal glands, liver and fat cells, and has some other roles in the body including healthy bone maintenance and cholesterol regulation.
There is in fact, three types of estrogens: oestrone, oestradiol, oestriol. Estradiol is the most abundant form in women of reproductive age. Oestrone is produced by the Uterus during pregnancy, and Oestriol is most abundant post-menopause.
Estrogen directly opposes, and therefore decreases the activity of one of the major fat storing enzymes lipoprotein lipase (LPL). Essentially making the body less prone to fat storage and more prone to fat mobilization. Estrogen also opposes Cortisol, increases serotonin and endorphins in the brain, as well as the neurotransmitter acetylcholine, and improves leptin signaling. It also increases the production of bile in the Gall Bladder.
High levels of estrogen can impair collagen synthesis and neuromuscular control, as well as increase weight gain, PMS symptoms, fibrocystic breasts and more.
This hormone is secreted by the Corpus Luteum during the Luteal phase. It acts as a protector and thickener of the endometrial lining. If pregnancy occurs, the ovaries and adrenal glands will continue to secrete Progesterone, to support embryonic growth, protect the endometrial wall and create a mucus membrane to seal the cervix.
Progesterone inhibits the action of estrogen by suppressing the enzyme that promotes estrogen synthesis. Additionally, progesterone enhances the function of serotonin receptors in the brain, acts an anti-inflammatory agent, is also involved in regulating the immune system and bone strengthening. Progesterone is the ‘protector’ hormone – it instills worry, anxiety and a heightened sense of awareness and attention to detail.
- Follicle Stimulating Hormone (FSH)
This hormone is secreted by the Pituitary Gland in the brain. FSH stimulates the ovaries to produce eggs and mature a follicle for release, and is also involved in development during puberty.
- Luteinizing Hormone (LH)
This hormone is secreted in an acute manner by the pituitary gland and stimulates ovulation, and development of the Corpus Luteum, from the Follicle.
- TRAINING & NUTRITIONAL CONSIDERATIONS
Having a basic understanding of the phases of the cycle, and their respective hormonal profiles, enables us to better understand the systems at play and how to manipulate the variables to better target the forces that may or may not be working to our advantage.
A dominant hormone characterizes each phase, and as hormones do this effects many functions of the body.
The Follicular Phase is characterized by the hormonal profile of Estrogen. During this phase, lasting from Day 1 of Menses to roughly Day 10-14, or whenever Ovulation occurs, Estrogen production is ramped up and levels are on the rise. The other hormone that is dominant during this phase is FSH, however its’ affects are less noticeable. Characteristics of the Follicular Phase include stable body temperature, an increase in insulin sensitivity, suppression of appetite, metabolic function and rate slowly beginning to rise post-menses and more.
Energy and mood are boosted, females will feel more optimistic, sociable and outgoing and as well experiencing an increase in libido. This phase is also characterized by increased cognitive and intramuscular function, motivation and focus. This is a good time for goal setting, starting new programs, planning and making important decisions.
With an increase in energy production, mood and intramuscular function, this period is optimal for phases of increasing load, periods of intensification and improving relative strength and power in motor patterns.
There is a slight increase in metabolic rate, and insulin sensitivity meaning that this is the time in her cycle when a female is most tolerant of carbohydrates, as the body is more primed for glycolysis, or the burning or glucose to produce energy. Ironically, it is also a period of suppressed appetite, due to estrogen influence on leptin signaling in the brain.
To support her hormonal health, during this phase a female should limit sodium intake, increase consumption of iron, B6 and B12 rich foods such as seafood, red meat, pork, chicken, eggs, broccoli and dark leafy greens such as spinach. It is also a good idea to supplement with a high quality pharmaceutical grade fish oil.
The end of the follicular phase is marked with Ovulation, which has some pretty special characteristics and advantages of its’ own. Ovulation can occur anywhere between days 10-14 of the cycle, and is characterized by a sharp rise in luteinizing hormone and follicle stimulating hormone, which causes the follicle to release a mature egg and transform into the Corpus Luteum. It is the peak of her metabolic rate in her cycle as post ovulation metabolic processes begin to decrease slightly.
This is also the time when estrogen levels peak in the body, increasing the pain threshold and force‐generation capability of your client, as well as a heightened state of confidence, mood, energy, brain function and optimism.
This is well and truly, peak week, and is the optimal time for a female client to attempt a new PR, or break through a training barrier. However, some studies have shown an increased risk of injury during this period, so ensure correct form is strictly adhered to!
The Luteal Phase lasts (or in many cases is endured!) from roughly days 15-28 or until day 1 of Menses. During the first half of the luteal phase progesterone begins to rise, whilst luteinizing hormone drops. Estrogen drops post-ovulation, then begins to rise again pre-menses.
The metabolic functions are starting to increase again, with it the thermic effect of food and the body is more primed to burn fat during this phase. This is a great phase when it comes to female fat loss! However, insulin sensitivity is decreased, and cravings for salt, sugar, fat are common so diet should be carefully managed during this phase.
Some women experience pre-PMS symptoms such as irritability, tiredness, forgetfulness, depression, being tongue-tied, brain fog, and a decrease in libido during this phase as well. In the second half of the luteal phase, estrogen dropping depletes serotonin and other happy neurochemicals in the brain leading to (further) moodiness, fatigue, depression, insomnia, and muscle aches.
I often find clients who are heavily affected by PMS benefit from a deload week during this phase. It is also an optimal time to reset all volume targets and conduct reviews or assessments, as women are more analytical during this phase. Recovery and stress management are often crucial components during this phase, and the inclusion of activities such as massage, float tanks, yoga and walking can help to replete serotonin.
In terms of nutritional support, a reduction in calorie and a shift in macros to a lower carbohydrate model can help to support the body’s fat loss mechanisms during this phase. Foods that should be limited include egg yolks, dairy, red meat, saturated fat, starch, sugar, sodium and alcohol.
Women should also increase their intake of fibre to reduce bloating, turkey, and healthy fats. Some beneficial supplements during this phase include fish oil, thiamin, riboflavin, niacin, folate, B6 and B12 along with calcium, vitamin D, magnesium, and zinc. When it comes to training during this phase, every female is different and every month can be too!
HIIT, or metabolic style workouts works well during this phase, if the intensity is tolerable. Additionally, low intensity steady state cardio is a great option during this phase for both fat loss and restorative purposes.
In closing, as personal trainers it is important to know the ins and outs of the female menstrual cycle, as it will influence not only what you prescribe with them, but also how you interact!