Menstruation and Fat Loss

Men and women, although possessing many similarities, have obvious differences with menstruation being one of the most evident. With regards to training and nutrition it’s important both coach/trainer and client have a basic level of understanding on the subject.

What is menstruation?

This is a one month cycle that women go through from puberty up until menopause (discussed later) and is to prepare women for the potential event of pregnancy. Within this month there is a change in hormonal balance. Understanding these changes and adjusting to suit can potentially lead to successful fat loss.

The cycle is determined by two phases, follicular & luteal. I am not going to discuss these phases in depth but more to highlight the change of hormone and how changing nutrition to suit could be of huge benefit to fat loss.

NOTE: The two phases can be broken down into early, mid and late but for the sake of simplicity I will refer to the two main parts.

The follicular phase:

This is the first half of the cycle and going off the premise a cycle is 28 days (can be anywhere from 24-32) this will last for 14-days. At this point Estrogen is the dominant hormone.

The luteal phase:

The second part of the cycle is the luteal phase and this will take up the remaining 14-days. At this point Progesterone is the dominant hormone.

Estrogen & Progesterone are the two major hormones that we are going to take note of. Understanding the effects each one has on a women’s physiology could be a game changer for fat loss.

The following table highlights the effects both Estrogen and Progesterone have during each phase:





8-14 15-21


Phase Early Follicular Late Follicular Early Luteal Late Luteal
Note Menses (3-5 day)


PMS (4-7days)
Dominant hormone Estrogen Estrogen Progesterone Progesterone
Insulin sensitivity High High Lowered Lowered
Fuel at rest Carbs Carbs Fat Fat
Fuel during exercise Fat Fat Fat (increased) Fat (increased)
Fat storage Lowered Lowered Increased Increased
Metabolic rate Normal Normal Increased increased
Hunger Lowered Lowered Increased Increased
Blood glucose Stable Stable Unstable Unstable
Water retention Lowered Increased Lowered Increased
Muscle growth Increased Increased Decreased Decreased


Table: The Women’s Book: Vol 1, A guide to nutrition, fat loss and muscle gain by Lyle McDonald  

Insulin sensitivity:

When Estrogen is dominant insulin sensitivity is higher. This means the body will burn more carbohydrates for fuel. When Progesterone is dominant insulin resistance develops which means carbs become harder to use as fuel. Therefore fat is used as the dominant source.

Metabolic rate:

From viewing the table Progesterone has many negative effects but it is worth noting the one major benefit of progesterone is the increase of metabolic rate.

Progesterone is a cause for the increase in body temperature after ovulation. With the increase of temperature comes an increase in energy expenditure and resting metabolic rate. Basically burning more calories at rest.

Ten days out of the fourteen it has been observed that metabolic rate can increase anywhere between 100-300cals per day. Over a ten-day period this could make up 1000-3000 extra calories. The draw back however is that diet must be controlled and managed throughout this time (more on this below)


Leptin is a hormone that regulates hunger. It basically lets us know when we are full. When Estrogen is dominant it increases leptin production. Not only this, it actually sends its own leptin-like signal to the brain further increasing the benefits. When Estrogen is elevated it also increases the hormones serotonin (controls mood and appetite) and dopamine (part of the reward system). When Estrogen decreases not only does leptin become inhibited but both serotonin and dopamine decrease. This can lead to depression and carb cravings (Serotonin) and cravings for high calorie/high sugar foods (Dopamine).

Blood glucose:

Speaking of cravings, when our blood glucose level is unstable this will also cause a shift to more sugary based foods, which is why many women turn to high calorie foods such as chocolate during the later phase of menstruation.

What can you do?

Adapt nutrition to suit each time of the month. For the early to late phase of follicular it would make be of benefit to have a higher carb based diet due to the body’s ability to utalise this for energy. Once the luteal phase is reached a shift to a fat dominant diet could be of benefit.

Note: Although not spoken about in this article it is worth mentioning that the negative effects of Estrogen are primarily seen when combined with a high fat diet.

To take full advantage of the increased metabolism due to the dominance of Progesterone (luteal) it is of importance that cravings are controlled. Unfortunately at this point hormones are not working in your favour so a more vigilant approach towards nutrition would be recommended. Increase fibre intake, stay hydrated and make sure your meals consist of adequate protein. I would also recommend opting for more fibre based carbohydrates due to insulin sensitivity being lowered. This will help control blood glucose levels.





This is the time when menstruation ceases with both Estrogen and Progesterone declining and eventually stopping from being produced. The effects of menopause have been likened to the luteal phase of menstruation (see above for effects).

I will highlight below other effects of menopause and recommendations to help:

  • Development of insulin resistance

As with the luteal phase it could be of benefit to lower carbs and increase fat. This will simply be individual specific with series of trial and error experiments to see what works

  • Shift of fat patterning from lower body to more male like central holding due to the decrease (cessation) of Estrogen.

With this there comes an increase of heart disease. It is important that lifestyle factors, nutrition and exercise, are of high importance to manage body fat levels.

  • Increase body weight and fat levels with a reduction of energy expenditure and metabolic rate

Increase metabolism by building muscle tissue through a progressive strength training program. Improve energy expenditure by moving more and becoming active on a daily basis. Manage fat levels by controlling energy balance.

  • The lack of Estrogen causes a loss in bone mineral density (BMD). This is why women are more susceptible to osteopenia and osteoporosis in later life.

Strength training helps improve BMD. If there was a single reason for women to strength train then this would be it.

Also consider that postmenopausal testosterone levels increase slightly. This could be a good time to shift the focus on building a little muscle tissue.

This is just a basic insight to menstruation and the change of a women’s physiology throughout. For a more in-depth understanding I would highly recommend the following book:

The Women’s Book: Vol 1, A guide to nutrition, fat loss and muscle gain by Lyle McDonald  

My intention is help people improve their lives, develop their physiques and build a confident and healthy body. If you know someone who can benefit from this, please share. If you would like to leave a comment please feel free as this helps develop improved content