Something we see a lot in clinic is the popularity of intermittent fasting in women. Although there is lots of research available to back up the benefits, it is important to consider that men and women are hormonally different and what might benefit men may not always be best for women and their hormones.
Today we are here to unpack the issues surrounding intermittent fasting and our hormones to help you decide if this popular eating style is really for you.
What is Intermittent Fasting?
Intermittent fasting is an eating pattern that cycles between periods of fasting and eating. The amount of fasting windows can differ depending on the style of intermittent fasting you are following. Some people choose to go hours with out eating and some choose days.
The two most popular styles of intermittent fasting are:
The 16/8 method
This involves consuming meals during an 8-hour window and fasting for the remaining 16 hours of the day. For example, only eating between 12pm and 8pm.
The 5/2 method
This involves eating normally for five days, and then for two days you restrict your calories intake to 25% of your usual daily intake.
What does the research say?
The goal of intermittent fasting is to get insulin levels to drop dramatically so the body uses fat for energy instead of sugar. There is some research that supports the use of intermittent fasting as a tool to improve insulin sensitivity, support weight loss, promote healthy cholesterol levels and improve inflammatory conditions.
However, the problem with this research is that majority of the studies have been conducted on animals with few human studies conducted. Those that include humans, the sample groups are largely limited to men and very few account for the differences in women’s physiology. This is very important factor because as we know women are hormonally very different.
One of the few studies that included both males and females found that intermittent fasting improved blood sugar control in men, but not in females and triggered a bigger stress response when compared to men. Another systematic review in 2017 showed that women reported increased feelings of hunger, worse mood, heightened irritability, difficulties concentrating, increased fatigue, eating-related thoughts, fear of loss of control and overeating during non-restricted days, following four weeks of intermittent fasting. Although this study is small, it highlights the potential disadvantages of intermittent fasting healthy weight women.
Why women should think twice about intermittent fasting
The female body and reproductive system can be super sensitive to restrictive diets. Restrictive diets that have a low kilojule intake can affect the hypothalmus and disrupt the secretion of gonadotropin-releasing hormones (GnRH) which are responsible for the release of two reproductive hormones called the follicle stimulating hormone (FSH) and the luteinizing hormone (LH). When these hormones are not functioning well and cannot communicate with the ovaries, it may result in reduced estrogen and progesterone, irregular periods, amenorrhea, infertility, poor bone health, and reduction in ovary size.
Altered Stress Response
The female reproductive system is incredibly sensitive to stress. So much so that the hypothalamus will slow down the production of our sex hormones required for ovulation and menstruation when under stress. Regularly fasting for extended periods of time or following restrictive diet plans can initiate a stress response in the body and therefore can trigger the reproductive system to shut down ovulation. This is because the body will always prioritise survival over supporting pregnancy. This in turn can lead to hormonal imbalances, menstrual irregularities and reduce the chances on conception.
Disordered Eating Habits
Another big issue with intermittent fasting is that it can promote disordered eating patterns. We know this because restrictive and controlled diet plans like that requires restriction and control can lead to worsening the relationship with food and increase the likelihood of eating disorders. For the many women with a long history of disordered eating, intermittent fasting can be very dangerous as it encourages restriction and limits intuitive eating.
Which women should always avoid Intermittent Fasting?
- Pregnant or breastfeeding women should always avoid intermittent fasting. This is time where we require more nutrients to grow and feed our babies.
- Women with known hormonal imbalances, especially those trying to conceive or those with missing periods and missing ovulation.
- Women who have dysregulated blood sugar levels or Diabetes. Fasting for a long period of time can lead to a dangerous state of hypoglycaemia in diabetics.
- Those with chronic stress or hypothalamic-pituitary-adrenal axis (HPA-axis) dysregulation.
Here at the Mungbean Clinic, we always encourage our clients to tune into their bodies unique energy needs and nourish it with wholefoods. If you are feeling lost with your diet, reach out to us as our team of naturopaths can support you with your unique needs.