Intermittent fasting can accelerate weight loss, but is it safe for women? In this post, I’ll share what the research has to say about the safety of intermittent fasting during a woman’s life — from childhood through the reproductive years to post-menopause.
Is Intermittent Fasting Safe for Women – Summary
- Fasting is not recommended for young girls. A child’s body requires a steady supply of calories for growth and development.
- To avoid a drop in calories that could disrupt her menstrual cycle, fasting is not advisable for a teenage girl, particularly at puberty.
- A woman in her 20s, 30s, and 40s can safely practice fasting but will do best to look at short-term fasting routines that do not result in large calorie deficits.
- Women who are pregnant, breastfeeding, frail, or who have a history of eating disorders should not practice intermittent fasting.
- Fasting is safe for pre-and postmenopausal women of normal health. Fasting may provide benefits beyond weight loss, including a reduced risk of metabolic syndrome and muscle preservation.
Is Intermittent Fasting Safe for Women? [Video]
In this video, you’ll learn…
- How intermittent fasting affects girls and women of all ages
- What women in their 20s, 30, and 40s must consider when fasting
- Fasting benefits beyond weight loss for adult women
Girls and Fasting
There is no doubt that childhood obesity has become a problem. However, there is no evidence to support the use of fasting to combat this problem. This is partly because the studies don’t exist. It is not realistic to subject young girls or boys to periods of fasting to determine if it hurts them.
A child’s body also uses calories for growth and development, so a child may benefit physically and mentally from eating throughout the day. Therefore, when it comes to children and fasting, providing guidance on food choices to reduce refined carbs and sugary drinks is better than skipping meals.
Teenagers and Fasting
As a girl moves through puberty and into adolescence, the primary safety concern is that calorie intake does not drop to a point where her menstrual cycle could be disrupted.
An observational study of teenage girls who fasted during Ramadan found that regular fasting caused changes in girls’ menstrual cycles, especially in menstrual blood volume (1).
These types of studies rely on self-reporting, which leaves many questions unanswered. However, because of the complex hormonal changes that come with puberty, fasting would not be advisable for a teenage girl, particularly at the onset of puberty.
Adult Women of Reproductive Age and Fasting
For a woman in her 20s, 30s, and 40s, fasting can be safely performed and beneficial. However, the safety concern of disrupting the menstrual cycle persists.
While the research to date is limited, we have enough evidence from animal and human studies to show that longer-term fasts, such as full-day fasting or other regimens that cause a large calorie deficit, may disrupt the menstrual cycle (2) (3).
Therefore, adult women of reproductive age will do best to look at short-term fasting routines that do not result in large calorie deficits. A good target range to aim for would be anywhere from 12 hours to 16 hours of fasting.
This time frame will provide the blood sugar and insulin steadying effects that promote weight loss and hunger control but lessen concerns about reproductive health. Of course, regardless of age, women need to eat well during their eating window to ensure proper nutrition.
Pregnant or Breast Feeding and Fasting
This emphasis on proper nutrition becomes even more of a focus for women who are pregnant or breastfeeding. At this stage in a woman’s life, fasting is not recommended.
Nutrition is vital for a developing fetus so it can grow and thrive within the womb. A breastfed baby obtains all of their nutrients from their mom, so nutritional care should continue after giving birth.
I am not suggesting that fasting will cause a pregnant or breastfeeding mother to suffer from malnutrition, but this is not a time of life to experiment with your eating routine.
Pregnancy and breastfeeding are two unique periods in a woman’s life, and although fasting is not recommended for those times, it doesn’t preclude a woman from using fasting at other times in her life.
If a woman is looking to become pregnant, it is wise to consult with her doctor before embarking on a fasting routine.
History of Eating Disorders or Underweight and Fasting
Another special consideration is the woman’s past health history and body composition. For instance, fasting would be ill-advised for those with a history of an eating disorder or those currently underweight or in a frail or weakened state.
For these subsets of individuals, proper nutrition is essential, so the restriction of food or calories is not recommended.
Pre- and Post-Menopausal Women and Fasting
As we continue to age and move into our pre-and postmenopausal years, fasting is safe to practice. When done wisely, fasting provides extra perks for older women.
A research team dug through the scientific literature looking for studies related to fasting, women’s health, and women’s disorders. They found that fasting was effective in reducing belly fat.
Managing belly fat is of interest to women of all ages but particularly important for postmenopausal women. Increased belly fat contributes to a condition called metabolic syndrome, a collection of health issues that increases a postmenopausal woman’s risk of cardiovascular disease and diabetes.
Fasting was found to combat metabolic syndrome, which would have an overall heart-protective effect on women as they age.
Additional Health Benefits as We Age
The benefits did not stop there. The research team also found evidence that fasting may aid in the treatment of certain cancers, improve bone health, and reduce inflammation in the body, which is an underlying condition in many chronic diseases.
The research team concluded that although there is a need for large, well-designed studies on women and fasting, “fasting can be prescribed as a safe medical intervention as well as a lifestyle regimen which can improve women’s health in many folds” (4).
These benefits can be had even when a woman is well past menopause. One of the main determinates of how well we will age is our ability to preserve muscle mass. In a 6-week study, overweight women who were 60 years of age or older were placed on a fasting regimen that involved fasting from 8pm until noon the next day.
This is a popular method that is often referred to as 16:8 intermittent fasting. The women were not restricted regarding their food choices once their eating window opened up. Yet, by the end of the 6-weeks, they lost an average of 4.4 pounds (2kg) with no significant loss of muscle mass.
These results were obtained, not because they dieted, but because they ate their calories within a shortened number of hours (5).
Aside from the cautions mentioned earlier, the scientific literature has revealed that fasting, when done wisely, is a safe practice for adult women of all ages.
The results are enhanced when fasting is paired with a proper diet. If you are interested in starting or enhancing your use of fasting, I encourage you to grab a copy of my book, The Intermittent Fasting Diet Guide and Cookbook. It shares the best fasting methods for women and provides diet advice and more than 50 recipes so that you have everything you need to make fasting work for you.
Thank you for reading and have a wonderful week!
(1) Ikhsan, Muhammad, Muhammad Fidel Ganis Siregar, and R. Muharam. “The relationship between Ramadan fasting with menstrual cycle pattern changes in teenagers.” Middle East Fertility Society Journal 22.1 (2017): 43-47.
(2) Kumar, Sushil, and Gurcharan Kaur. “Intermittent fasting dietary restriction regimen negatively influences reproduction in young rats: a study of hypothalamo-hypophysial-gonadal axis.” PloS one 8.1 (2013): e52416.
(3) Meczekalski, B., et al. “Functional hypothalamic amenorrhea and its influence on women’s health.” Journal of endocrinological investigation 37.11 (2014): 1049-1056.
(4) Nair, Pradeep MK, and Pranav G. Khawale. “Role of therapeutic fasting in women’s health: An overview.” Journal of mid-life health 7.2 (2016): 61.
(5) Domaszewski, Przemysław, et al. “Effect of a Six-Week Intermittent Fasting Intervention Program on the Composition of the Human Body in Women over 60 Years of Age.” International Journal of Environmental Research and Public Health 17.11 (2020): 4138.
About the Author
Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.