You’ve likely heard of intermittent fasting and its positive effects on weight loss. Intermittent fasting is a popular eating method as it doesn’t require you to restrict certain food groups or weigh your meals.
Yet one benefit of intermittent fasting that you may not be aware of is its potential to help women achieve hormone balance. However, in order to harness the positive effects, intermittent fasting needs to be done correctly, otherwise, you could end up with a hormonal imbalance.
Why Intermittent Fasting is Beneficial
Intermittent fasting is a scheduled way of eating where you fast for a period of time, generally 12-16 hours or more. For weight loss, this helps to reduce your overall calorie intake and trains your body to become a fat-burning machine.
But studies have revealed intermittent fasting has many potential benefits including:
- Improved insulin sensitivity
- Reduced risk of type 2 diabetes
- Increased energy
- Enhanced cognitive function and memory
- Improved heart health
- Strengthened immunity
- Reduced risk of neurodegenerative diseases
The Effects of Fasting and Hormones
Intermittent fasting, when done correctly, can have a positive effect on our hormones. And while there tends to be a lot of focus around the positive benefits of insulin and fasting, there are other hormones that can benefit or be compromised by this eating method.
Fasting and insulin
There is a growing body of research into the effects of intermittent fasting in lowering insulin resistance and increasing metabolism. This is vital for those with blood sugar problems, pre-diabetes (insulin resistance) or type 2 diabetics.
When we eat, insulin levels rise. It’s the hormone that signals to your cells to accept the delivery of glucose for fuel.
When we don’t eat, our blood glucose levels remain normal and the body switches to burning fat for energy. This can be seen in fasting periods as short 16 hours and even during alternate day fasting.
When the communication between insulin and our cells is compromised, insulin resistance can occur. The insulin signals to the cells that fuel is coming, but they don’t respond and receive the glucose. The glucose then stays in the bloodstream, raising your blood sugar levels, before being stored as fat.
At the same time, your pancreas continues to produce more and more insulin to get the cells to respond. If the communication breaks down and the cells don’t respond, the pancreas becomes exhausted, blood sugar imbalanced and fat storage increased.
Fasting on a regular and basis not only can lower insulin levels but also significantly improve insulin sensitivity. which is not often addressed in most diets. This can have a beneficial effect on persisting issues such as weight gain.
Fasting and Leptin & Ghrelin
Improving hunger balance, intermittent fasting also helps to overcome leptin resistance. Leptin, also known as the “starvation hormone”, is produced in fat cells and tells your brain if you have eaten enough and your calorie intake is sufficient.
In the case of leptin resistance, the brain stops recognising these signals and doesn’t think that you’ve consumed enough food, interrupting this scenario as starvation. As a result, the brain turns on your hunger signals and you need more food than necessary to feel full.
Your brain is essentially starving but your body is getting fatter. Body fat is the main regular of leptin production and levels will fluctuate depending on your weight. Generally speaking, when you gain more body fat, your levels of leptin will increase.
Ghrelin, “the hunger hormone”, increases your desire to eat. These two hormones work in balance and changes in leptin can also be helpful in regulating ghrelin levels.
Intermittent fasting methods have been associated with a decrease in insulin levels improved leptin sensitivity and controlling ghrelin levels. When these are in balance your ability to eat when you’re actually hungry and stop when you’re full is better controlled. Long-term, this can help to overcome weight-loss resistance.
Fasting and Human Growth Hormone
Human growth hormone (HGH) has many positive benefits including increasing the availability and utilities of fat as fuel and preserving muscle mass and bone density. Unfortunately, the production and secretion of HGH decline steadily as we age which is associated with an increase in fatty tissue and a reduction in muscle mass.
Fasting has been found to stimulate the secretion of HGH significantly helping to change the body composition while maintaining muscle and bone tissue mass. Studies have found, long-term fasting is a more effective strategy at preserving lean muscle mass than adhering to a calorie-restrictive diet.
Fasting and Cortisol
Cortisol is released by your adrenal glands and is the main stress hormone. One of its main effects is that it increases blood sugar levels and influences insulin production. Cortisol dysregulation can actually be the cause of blood sugar imbalances and lead to conditions such as adrenal fatigue.
Fasting is a form of stress on the body. Just like exercise, in good doses, these forms of stress are healthy. However, if you’re already suffering from excess stress, fasting is not the answer to your hormone imbalances or weight loss woes.
Intermittent fasting can actually wreak havoc and cause high blood sugar levels to get worse. This is particularly the case for women. Yes, this form of eating is helpful for lowing insulin and getting control of our hunger hormones, but stress management practices are key.
Once cortisol levels have somewhat normalised, a slow introduction to fasting or crescendo approach is recommended.
Fasting and Oestrogen and Progesterone
Intermittent fasting appears to have a greater impact on women than it does men, particularly when it comes to the hormones oestrogen and progesterone.
The production of our sex hormones is largely controlled by the hypothalamic-pituitary-gonadal (HPG) axis. This happens in a cascade of chain reactions:
- The hypothalamus is stimulated to release gonadotropin-releasing hormone (GnRH).
- This causes the pituitary gland to produce luteinizing hormone (LH) and follicular stimulating hormone (FSH).
- For women, this causes the production of osteogen and progesterone in the ovaries. For men, the testes produce testosterone and sperm production is stimulated.
This sequence of reactions occurs on a regular cycle and is very sensitive to changes in your body’s environment, including fasting. Even short fasting periods can affect the release of GnRH and therefore affect the entire cascade and production of sex hormones.
For women, when this cascade is disrupted irregular periods, infertility and other hormonal issues may occur.
A women’s reproductive function and hormone balance is also closely connected and influenced by metabolic function. Increased or reduced insulin levels can affect the production of oestrogen, progesterone and testosterone.
In the case of fasting, the women’s body can switch into a preserve and protect stress mode and the starvation signal is activated. The body can hold onto weight, increase the production of ghrelin and leptin and slows down non-essential functions, including reproduction.
Does that mean women shouldn’t intermittent fast? Not necessarily. In fact, some women find fasting can have positive benefits when done in a hormone-friendly way. Gentler intermittent fasting protocols that don’t jeopardise hormone function are recommended. Additionally, ensuring the diet includes healthy fats for proper hormone synthesis and to help manage systems such as brain fog and irritability that can be associated with longer fasts.
Fasting and Thyroid Hormones
Our thyroid hormones T3 and T4 have an impact on every system and cell in the body. Intermittent fasting impacts our thyroid hormones, metabolism and energy production.
There is very little research into the effects of intermittent fasting and thyroid health, however, studies reveal during a fast, T3 decreases and there is an increase in reverse T3 levels. This is due to a reduced rate of conversion from T4 to T3 as the body tries to conserve as much energy as possible. Thyroid hormone balance resumes once you commence eating again.
Some research into the thyroid function of men reported insufficient effects of fasting and thyroid function, however, women may experience a drop in both T3 and T4.
Another study comparing calorie restriction to alternate-day fasting found in people who had hypothyroid (an underactive thyroid), fasting achieved the same weight and body fat loss but greater improvements in their fasting insulin and insulin resistance was seen.
Effects of fasting and thyroid function will be different depending on your thyroid hormone production and whether you’re taking thyroid medication. However, there are some key things to consider particularly in relation to the female body:
- Ensuring you’re providing nutrients for optimal thyroid hormone function
- Choosing a shorter fast duration
- Avoiding calorie restriction and fasting
- Focusing on stress management as stress inhibits the conversion of T4 to T3
- Ensuring you’re getting enough quality sleep
The Bottom Line
When considering the effects on hormone balance, it’s important to remember intermittent fasting protocols vary, with some more extreme in duration than others. Factors such as sex, age, nutritional status, exercise, sleep and stress are also relevant in how effective this way of eating is and the impact it will have on the body.
There are very few human studies into the effects of hormone balance and fasting, and the differences between men and women. Early evidence suggests long fasting windows have the potential to throw off a woman’s hormonal balance which can lead to menstrual irregularities, fertility issues and disordered eating behaviour.
If you’re considering a fast to achieve hormone balance, best to speak to your health practitioner to establish whether it’s right for you.
Explore in more detail
- A Beginner’s Guide To Intermittent Fasting
- A Guide To The 16:8 Fast
- A Guide To The 20:4 Fast
- A Guide To The 5:2 Fast
- Intermittent Fasting And Exercise
- Intermittent Fasting And Hormone Balance
- Intermittent Fasting And Keto
- Intermittent Fasting And Type 2 Diabetes
- Intermittent Fasting And Weight Loss
- Intermittent Fasting: Tips To Starting Your First Fast
- Side Effects Of Intermittent Fasting
- Tips For Intermittent Fasting Success
- Top FAQs Of Intermittent Fasting