An Overview Of The Menstrual Cycle Changes

Going back to the latest blogs, let's now summarize the changes that are occurring.

Early and Late Follicular Phase

After menstruation, during the early follicular phase, estrogen and progesterone are both fairly low although estrogen will start to increase and have the dominant effect overall. Insulin sensitivity will be high with a woman's body using more carbohydrate for fuel at rest. Appetite and hunger will be stable and controlled, especially in comparison to the previous luteal phase. Blood glucose levels will remain stable as well. Her metabolic rate will be normal and fat storage will be normal and/or lowered at least relative to the luteal phase. Estrogen will be exerting anti-inflammatory effects and have a positive effect on muscular remodeling from training. Early in the follicular phase, water retention will be low after any retention from the previous late-luteal phase has disappeared and this is when women will show their lowest bodyweight. For the most part all of the above will hold in both the early and late follicular phase with one or two exceptions. Due to the surge in estrogen, appetite will be reduced significantly in the 3-4 days prior to ovulation. This same surge can cause water retention, especially if a woman is on a high sodium diet

Early Luteal Phase

During the early luteal phase, most of the above reverses or at least starts to reverse. Body temperature increases slightly and with this will come a small increase in metabolic rate. Hunger and cravings will tend to go up both due to the fall in estrogen after ovulation along with increasing progesterone levels. This can cause an increase in food intake that can easily overwhelm the small increase in metabolic rate. Due to the impact of progesterone on both LPL and ASP, fat storage will be higher than in the follicular phase and this is compounded by estrogen's effects both on anti-fat mobilizing receptors and it's sensitizing of the progesterone receptor. Since progesterone causes insulin resistance, a woman's body will use more fat for fuel (and less carbohydrates) both at rest and during exercise but the fat comes from within the muscle. Blood sugar becomes unstable and this can cause energy and mood swings along with hunger. Binding of progesterone to the aldosterone receptor will cause a loss of body water and there tends to be little water retention during this phase. Due to the negative impact of progesterone on muscle along with it's blocking of the androgen receptor, muscle growth and remodeling are negatively impacted. The increase in body temperature may harm endurance performance especially in the heat.

Late Luteal Phase/PMS/PMDD

Moving into the late luteal phase, estrogen and progesterone continue to drop and this has a large number of effects on a woman's body. Blood sugar levels often become even more unstable during this time period and this can cause women to experience low blood sugar (hypoglycemia) negatively affecting energy, mood and hunger. Just as with earlier in the luteal phase, cravings for high-fat and high-sugar foods are usually high here, related both to the drop in serotonin and dopamine levels. Falling dopamine levels also cause levels of the hormone prolactin to increase, causing breast tenderness. The same basic pattern of fat storage and fuel utilization seen in the early luteal phase will be maintained. As progesterone drops, there is a rebound effect with water retention typically being the worst at this time with the effect being increased for women on a high-sodium diet.

While not frequently mentioned, sleep is often interrupted during the late luteal phase as well. Melatonin, a hormone predominantly involved in sleep, is more inhibited by the impact of even small amounts of light, and this can prevent women from sleeping well. There are a number of strategies including avoiding light late at night, sleeping in a dark and cool room that can help with this. A sleep mask may also be useful.

Finally, in that proportion of women that experience it at all, the late luteal phase is also when Premenstrual syndrome (PMS) or Premenstrual Dysphoric Disorder (PMDD) will typically occur. Again, there are different patterns here with some women experiencing symptoms in the early luteal phase or having those same symptoms continue through the first days of menstruation. Women may suffer from headaches, joint or muscle ache, digestive problems, issues with coordination and many others. Exhaustion, irritability, anger, problems with concentration and mood swings are common as well.

Antidepressants have shown a benefit for PMS and PMDD which further suggests that serotonin levels are involved with some of the typical PMS symptoms As well, due to low estrogen levels, a large percentage of women suffer from hot flashes, identical to what is seen after menopause. As mentioned, some women experience none of the traditional effects whatsoever.

Treating the symptoms of PMS have always been of great interest (for what should be obvious reasons) and many approaches have been tried or shown to be beneficial with an equal number of often claimed remedies having zero effect. Regular exercise appears to reduce the symptoms of PMS but this may be problematic if the presence of PMS or PMDD makes it difficult for women to maintain an exercise program. A number of dietary supplements, including specific vitamins and minerals along with others may help to alleviate many of the typical PMS symptoms as well and I will provide recommendations in later blogs.

Finally, in preparation for shedding the uterine lining and the start of menstruation, cramps are common here and these may continue into the early stages of menstruation as bleeding starts. Related to falling levels of progesterone, the cause of the cramping are prostaglandins, short lived chemical messengers, that cause the uterus to contract. As the late luteal phase ends, menstruation and the next cycle begins. .

Summary of the Menstrual cycle

I've summarised the primary general changes that occur in a woman's physiology that occur across the menstrual cycle. As you can see clearly in the chart below, there are changes in fuel utilisation, fat storage, hunger, appetite, water retention and others that occur due to the impact of either estrogen, progesterone with estrogen and progesterone typically having roughly opposite effects in the body. From a fat loss perspective, both estrogen and progesterone have positive and negative effects although it's arguable that the late luteal phase when progesterone is dominant is truly the problem time.

Hopefully the above chart makes it clear just how much more complicated a woman's physiology is compared to a man's. There are major changes occurring at least every 2 weeks and in some cases even more frequently than that. These changes interact, overlap and often reverse completely (in contrast, men are basically the same daily). Addressing women's needs for diet or fat loss means taking those changes into account, taking advantage of the positives while minimizing the negatives.

In the next blog we will start looking at Growth Hormone, Insulin, thyroid, The catecholamines and Leptin.

Coach HB


The above information is taken from the The Woman's Book by Lyle Mcdonald with Eric Elms

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