Menstrual cycles might impact our metabolism: from increased energy needs to favour carbs over fats, learning more about your body needs will help you choosing smarter meals, optimise workouts and successfully manage your symptoms
A menstrual cycle lasts on average 28 days (can range from 21 to 38 days) and comprises 2 main phases: the follicular phase and the luteal phase. However, the length of each cycle can vary from person to person and change over time for the same person which is perfectly normal.
Follicular Phase
This phase begins with the start of the period and lasts until ovulation takes place. When looking at what is happening at a hormonal level, progesterone and oestrogen are at their lowest levels. One week after period has started, oestrogen levels start to increase and reaches its peak right before ovulation happens (approx. day 14). Oestrogen levels drop drop right after ovulation.
Luteal Phase
Lasting from the moment ovulation takes place until the start of the next period, the hormone progesterone increases in the luteal phase. Prostaglandins are also produced to cause the uterine muscle to cramp and these increase towards the moment of period starting. This is why women experience abdominal pain cramps which can be, for some women, incapacitating.
Body metabolism, food intake and appetite
Follicular phase: studies shown a decreased food intake during this phase with the moment when ovulation happens being the lowest point of food intake.
Although some scientific papers found increased levels of leptin (one of the appetite hormones) in pre-menopausal women, it has not been proved to be related to the sexual hormones increase/decrease during the menstrual cycle. This means that sexual hormones are not to blame for changes in appetite in any particular phase of the menstrual cycle - at least in a direct way.
When it comes to preferred body fuel, during the follicular phase, there is an increased carbohydrate oxidation (and decreased fat and protein oxidation). This means that body's "food preferences" can influence and point towards which nutrients we should prioritise (and exercises) during the 2 main phases of the cycle. Stay tuned - more info below!
Luteal phase: in contrast with the previous phase, the food intake increased during the luteal phase - in particular on the last 10 days which precede the start of the period. It also seems to be the case for most women that both energy intake and expenditure are also higher in this phase (however, don't let this be the motive to eat larger quantities - tap to your emotions first!)
In terms of metabolic changes, oestrogen has an anabolic effect promoting a higher glycogen uptake and sparing the glycogen reserves. This is particularly relevant as it impacts the preferred body fuel - fat oxidation during the luteal phase is higher than in follicular phase which is assumedly accompanied by an increased metabolism of protein.
Additionally, oestrogen has also antioxidant and membrane stabiliser properties which in turn will protect the body against exercise-induced muscle damage and decrease the inflammatory responses to it.
These differences were, however, not found in women on oral contraceptives (i.e. contraceptive pill) or in those with anovulatory cycles.
Food preferences vs food cravings
Follicular phase: perhaps an easier phase to build new eating habits and embrace exercise, a balanced diet including wholefoods and complex carbohydrates will support more intense exercise. Maintaining healthy fats and protein as part of your diet will also ensure you are not missing essential nutrients.
Luteal phase: the preferred foods during this phase seem to be foods/diets higher in carbohydrates and fats, and lower in protein (as per studies' evidence). However, they may not be the best choice considering the body fuel of choice during this phase. With the increased likelihood of experiencing a drop on energy levels (related to hormonal changes), providing your body with healthy fats and optimise the protein content of your meals during this phase will support satiety levels and, simultaneously, nourish your body with the preferred fuel - fats and protein.
Tip: Make use of a diary (which can be in a form of an app) where you can register symptoms during your cycle, including food cravings, will help you understand and adjust your food plans, exercise routine and build self-compassion as you discover what works for you!
PMS (and PMS'ing!)
PreMenstrual Syndrome (PMS) can cause various symptoms before periods and can vary greatly in severity to the extent of affecting quality of life. Physiological PMS symptoms (e.g. abdominal bloating, breast tenderness, acne, constipation, headache and mood changes) are very common (9 out of 10 women experience it) and do not cause impairment of activities of daily living or affect quality of life. PMS, however, is when these symptoms cause significant problems.
The root cause of PMS is yet to be found. However, it is known that the higher the BMI, the increased severity of PMS seems to occur. Additionally, PMS symptoms seem to be triggered by the moment ovulation occurs - coincident with the increase of progesterone levels (which in turn relates to possible body mechanisms that explain how it affects women suffering with PMS). The figure below illustrates an overview of how this may feel like during a complete cycle.
During the time where a women experiences PMS, it often includes an increase in food cravings and increased food intake. The higher the severity is, the higher differences in food intake has been observed.
Despite the link found between increased intake of carbohydrates and negative mood and less physical activity, when it comes to women who suffer from PMS, opting for complex carbs and low protein meals, alleviates symptoms of anger, depression, confusion, sadness, and fatigue; and increased symptoms of alertness and calmness. It does go against the preferred fuel but, depending on your own symptoms (which can also vary in each month) and your health goals, just know it is not one rule fits all!
That said, by alleviating the psychological PMS symptoms and increasing satiety, it may help reducing the energy intake in women prone to have an increased consumption of sweet-fatty foods during the luteal phase.
Answer reveal: do I need to eat according to my menstrual cycle?
In a word - no! A 6-month RCT study found that women who were overweight and followed a weight loss diet that was adjusted to her menstrual cycle, had a higher success with and added +5kg weight lost when compared with the control group (who followed a traditional weight-loss program).
However, the adherence to this diet was low due to what it requires (3 separate meal plans per cycle) leading to the majority of the participants dropped out! Being aware and understanding what our body is telling you (through symptoms that, in turn, can lead to related thoughts and feelings) is important when changing habits.
Adding to the limitations of the study (sample size and participants' motivation ), choosing a sustainable, personalised health coaching plan that meets your health goals sets you for success and long-term results.
Running and menstrual cycles: what, when and why?
With the preferred body fuel in mind (as described above), the choices of exercises should reflect the former if you do identify with the changes explained by variations in the sexual hormones. Even though 29% of women in the UK make use of the pill as their main form of contraception (which will impact sexual hormones differently and linked symptoms), the withdrawal during the break between pill taking and/or change of type of contraception lead to some of the same symptoms which you will want to consider when experiencing them.
During your Period
Feeling low in energy and some level of discomfort may make you feel as you cannot exercise or follow an exercise routine - and that is OK! Being gentle and kind to yourself is important and it is wise to listen to your body.
On these days, instead of running, you can chose other gentle approaches that will not only contribute to keep you healthy and support your running performance/techniques and recovery but will also contribute to make you feel better and promote good energy levels.
Exercises: yoga, pilates, walking, stretching and/or foam rolling
And if you have a doing nothing day - that is also OK!
Follicular phase
Considering the predisposition of the body to favour higher intensity exercise, this is the preferred phase to "push" yourself as the motivation, energy and powered body are synchronised right until ovulation day.
For runners this may translate in practicing sprints, participating on a running event (which can even be virtual!) and/or join classes that work on core - since it is a key to support good posture and prevent injury.
Getting your metabolism/exercise routines challenged is also important to prevent weight stagnation and most importantly - boredom!
Exercises: HIIT (interval training with sprints or hill running), weight circuits, weightlifting, dancing classes, boxing/kickboxing, bootcamp
Luteal phase
Once ovulation takes place, oestrogen levels drop and progesterone starts to increase. In this phase it is of higher importance to include warm ups in particular BEFORE exercising - as there is a higher risk for injury.
As energy levels slowly decrease as you get closer to your period starting, it may be beneficial to chose gentler exercises which do not exclude running - on the contrary! As an aerobic exercise, running longer distances at a comfortable pace or even alternate walk/run/walk are ideal if running is your preferred exercise.
As symptoms may arise in the few days prior to your period, you may want to chose gentle exercises. Bear in mind that something like a short and paced run or brisk walk can help with the release and endorphins which in turn will ease period pain.
Exercises: running (paced, distance, trail), brisk walking, cycling, weights (with low intensity and more repetitions), swimming, rowing
With an increased knowledge on how your menstrual cycle plays a role on your feelings (and emotions!) and how it can impact your health goals, you can make better choices that meet your body needs! And enjoy every run!
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