Blog by Gina Burn, Naturopath
Fasting (going without food) is a common question I am asked as a Naturopath.
Fasting has been used for thousands of years and mainly for religious reasons.
Fasting has become popular now for people struggling with a chronic illness like cancer, autoimmune conditions and for stubborn weight loss issues.
A common type of fasting is the 16:8 diet – fasting for 16 hours and eating over an 8 hour window. This is to skip breakfast and consume meals between noon and 8 pm. A study on overweight adults showed that the 16:8 method resulted in reduced caloric intake, weight loss and improved insulin sensitivity, factors associated with increased longevity.
Professor Valter Longo, in his book The Longevity Diet is the culmination of 25 years of global research on aging, nutrition, and disease, this unique combination of an easy-to-follow “everyday” diet and short periods of fasting-mimicking diet (FMD) he explains is the key to living to a healthy old age. It avoids the negative stressors of starving yourself, such as low energy and sleeplessness.
Valter Longo, discovered that specific diets can activate stem cells and promote regeneration and rejuvenation in multiple organs to reduce the risk for diabetes, cancer, Alzheimer’s and heart disease. His daily nutrition plan, together with periodic fasting-mimicking techniques, has yielded startling results in the lab and in clinical trials.
Dr Mindy Pelz in her book Fast Like a Girl– beautifully outlines a healthy way for women to fast according to your hormones. Men have a 24-hour testosterone hormone cycle and so can fast anytime with generally good results. Women prior to menopause have an average 28 day hormonal cycle of 3 key hormones to look after- estrogen, progesterone and testosterone.
Dr Pelz explains that fasting in your estrogen phase may be more helpful with weight loss, energy and longevity rather than fasting in your progesterone phase. Estrogen doesn’t mind a lower blood sugar level, whereas progesterone likes carbohydrates, as women often know too well that craving of potato chips and chocolate before your cycle.
Pelz explains, during the ‘first power phase’ – the regenerating estrogen time (days 1-10), women with a cycle can try fasting for durations ranging from 13 hours or more.
Fasting may help lower insulin levels, which may be beneficial for conditions like PCOS, insulin resistance and energy levels.
The ‘manifestation phase’ (days 11-15) calls for shorter fasts, ideally between 13 and 15 hours a day.
The manifestation phase coincides with a surge in testosterone production. Given the limited research on female testosterone levels and fasting, Pelz recommends, based on male studies and her clinical observations, that fasts during this phase should not exceed 15 hours a day.
The second power phase (days 16-19) welcomes fasts of any length.
Lastly, from day 19 until the start of your next period (the ‘nurture phase’- the progesterone production time), it’s generally a good idea to steer clear of fasting. To eat foods that help progesterone such as sweet potatoes, white potatoes, beets, fennel, pumpkin, squash, quinoa and even some healthy cocao.
According to the studies outlined in Dr Pelz book…Intermittent fasting refers to fasts that last from 12 to 16 hours a day. Autophagy fasting – when your cells start healing themselves – begins once you hit 17 hours of fasting. A gut reset is a 24-hour fast. A fat-burner fast is 36 hours, and a dopamine-reset fast lasts 48 hours. These longer fasts should be aligned with a Health Care Professional, to support your journey.
With this guide, women can tailor fasting habits to sync with the cycle, maximizing the potential benefits of both. Just remember, everyone’s body is unique, so always listen to yours and make adjustments as needed. Fasting is not recommended if you are pregnant, breastfeeding, diabetic, underweight or have experienced eating disorders. Fasting results are best achieved when you are already on a healthy eating lifestyle for a least 4 months.
