If you’re into health, nutrition, and fitness, you’ve likely heard the buzz around intermittent fasting. But is this dietary trend right for everyone? What does traditional Chinese medical wisdom have to say about it? And what impact does it have on fertility?
What is intermittent fasting?
Intermittent fasting (IF) is an eating pattern that includes regular, short-term fasts. There are several models, one being Time-Restricted Eating. For this type of IF, you extend your regular overnight fast to between 12 to 16 hours by skipping either breakfast or dinner every day. One popular version of this approach is the 16:8 diet which involves fasting for 16 hours and condensing your eating into an eight-hour time slot.
Another form of IF includes Whole-Day Fasting, which, like it sounds, consists of fasting for 24 hours anywhere from once or twice a week to once or twice a month.
Some describe intermittent fasting as a lifestyle rather than a diet, since it doesn’t dictate what food you eat or avoid, but rather a pattern of eating. Proponents of IF point out that our hunter-gatherer ancestors would not have had three square meals a day, but rather times of feast and famine, depending on how well the hunt went.
While most research on IF has been done using lab animals, human trials have also been conducted and make up a growing body of work that shows its benefits. If done correctly, IF may help regulate blood glucose, improve blood lipids, reduce the risk of coronary disease, manage body weight, and reduce the risk of cancer and other chronic diseases. Ketogenesis — when your cells switch from burning glucose to burning fats — is one of the mechanisms behind the improved health seen with short-term fasting. Also, as you fast, your insulin levels drop and your levels of human growth hormone and norepinephrine increase, which has a positive impact on metabolism and longevity.
What does traditional Chinese medicine have to say about this lifestyle?
Chinese medical wisdom has long recommended eating during daylight and resting at night (including resting the digestive organs). This is part of living in harmony with the circadian cycles.
Traditional Chinese medical (TCM) wisdom around diet concurs with the adage “Eat breakfast like a king, lunch like a prince and dinner like a pauper.” According to the TCM meridian clock (a chronological map of the strength of the organs at different times of the day), the digestive organs of the Spleen and Stomach are most active in the morning (Stomach time being 7-9am and Spleen time 9-11am). So it makes sense to load up your calories earlier in the day, when the digestive fires are strongest.
Also in accordance with the meridian clock, Chinese medicine practitioners often recommend abstaining from eating for at least 2 hours before bedtime. This allows your food to begin to digest before you sleep, giving an important break to the digestive organs overnight. The Gallbladder and Liver have the most qi and blood from 11pm-1am (Gallbladder) and from 1-3am (Liver). During these hours, it is important for your body to be in a deep sleep state and not distracted by digestive tasks, otherwise the Liver will fail to get nourishment from the blood and will not be able to perform its many functions.
So TCM does support restricting eating to daylight hours, but rather than skipping breakfast, it would encourage skipping or going light on dinner. However, I don’t believe there is much support in TCM for whole-day fasting. In Chinese medical school, we learn that long fasts can weaken the Spleen Qi and lead to deficiencies. Instead, we should eat at regular intervals as the earth element (Spleen and Stomach) loves a routine. Eating at about the same times every day can help the gastrointestinal tract to perform optimally.
What is IF’s impact on fertility?
As a practitioner, I see many patients who are trying intermittent fasting and loving it. They see benefits like loss of fat, increase in lean body mass, and curbing unhealthy cravings. A few things to note about my patients who love IF, though — most of them are doing the Time-Restricted Eating variety and all of them are male.
I did some research on intermittent fasting in women and it seems that it may not always go down as well with us ladies. A small study found that blood sugar control worsened for women after 22 days of alternate-day fasting, while there was no adverse effect on blood sugar for men (Source). And while some women love IF, others report serious side effects like binge eating, metabolic disruption, lost menstrual periods, and early-onset menopause.
It’s important to understand that intermittent fasting is a stressor on the body. And just like other stressors such as lack of sleep, emotional stress, too much exercise, and illness, too little food can suppress our fertility. It happens through a tipping of the scales — energy gets taken away from the production of sex hormones and directed toward the production of stress hormones. The stress hormone cortisol inhibits GnRH (the precursor of our sex hormones) and suppresses the ovaries’ production of estrogen and progesterone, which plays havoc with our fertility. This makes sense from a biological perspective — during times of food shortage, our body needs to conserve resources, not make a huge expenditure on reproduction. Learn more about cortisol in Janice’s post Cortisol: The Goldilocks Hormone.
On the other hand, there are certain women- especially some with PCOS or with insulin resistance who find intermittent fasting helpful in conceiving. As a woman, you may be thinking, well, I’m not trying to get pregnant anyway. But it’s important to remember that estrogen and progesterone play many important roles in our body, from regulating our body temperature to protecting our cardiovascular health to balancing our mood.
For anyone considering intermittent fasting:
it is best to check with your doctor to know if it is a diet that is appropriate for you. Double Happiness Health- based Internal Medical doctor and Obesity specialist Dr. Priyanka Wali explains that anyone starting an IF protocol should first have labs checked such as iron, omega’s, B12 and Vit D. If you have an underlying nutritional deficiency and start IF, you may make things worse. Also, she points out that eating nutrient dense food during your eating window is of paramount importance. Don’t eat junk food when it’s time to eat.
With this knowledge in hand, I don’t discourage all my female patients from intermittent fasting, but I do recommend a gentler version, more in line with the Chinese medicine view. A 12-14 hour overnight fast seems a more reasonable length of fasting, giving time for the digestive organs to rest without pushing us into stressful territory. And I don’t recommend the whole-day fasting approach to my female patients.
If you are curious to try intermittent fasting, we highly recommend you get some lab testing first to rule out underlying nutritional deficiencies. When you practice intermittent fasting, be especially careful to eat nutrient dense food during your eating window and pay close attention to how you feel, both during the fast and during your eating hours. If you feel very “hangry” before your first meal of the day, you may want to shorten your fasting hours. And if you feel bloated, overly-full, and sluggish during your eating hours, your Spleen may be too deficient to effectively digest so much food at once. It’s always a good idea to check in with your Double Happiness practitioner before making any major dietary or lifestyle change.
CHINESE MEDICINE DIET RECOMMENDATIONS
Fasting, circadian rhythms, and time restricted feeding in healthy lifespan
Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting
INTERMITTENT FASTING FOR WOMEN: A BEGINNER’S GUIDE https://www.healthline.com/nutrition/intermittent-fasting-for-women
INTERMITTENT FASTING FOR WOMEN: IMPORTANT INFORMATION YOU NEED TO KNOW
INTERMITTENT FASTING: SURPRISING UPDATE https://health.harvard.edu/blog/intermittent-fasting-surprising-update-2018062914156
Intermittent Fasting: The Science Behind the Trend https://chriskresser.com/intermittent-fasting-the-science-behind-the-trend/
IS TIME-RESTRICTED EATING EFFECTIVE FOR WEIGHT LOSS?
LIVER IN CHINESE MEDICINE
16/8 INTERMITTENT FASTING: A BEGINNER’S GUIDE