Intermittent fasting (IF), a practice that extends the time you don’t eat (aka fast) in a day or week, has become extremely divisive in the health sphere between professionals and amateurs alike. Unlike other dieting approaches, this new and trendy dieting approach emphasizes WHEN you eat, not necessarily WHAT you eat.
There are many ways to practice intermittent fasting, most commonly by consuming a full day’s worth of calories within a small window of time, and then restricting food intake, or fasting, for the rest of the day. One of the most common protocols is the 16/8 fasting method: consuming calories within an eight-hour window, let’s say 10 am – 6 pm, and then fasting for the remaining sixteen hours of the day.
Whatever approach you use, intermittent fasting aims to extend the amount of time your body goes without consuming calories to first burn fat stores instead of carbohydrate stores for energy.
Is Intermittent Fasting Safe for Women?
Many people look to intermittent fasting as a weight loss approach. By reducing the window of time to consume food, caloric consumption will likely be reduced as a result. When reducing caloric intake, many people experience weight loss. It’s as simple as that!
However, there is minimal research on the long-term effects and safety of intermittent fasting—particularly for women of reproductive years. In fact, a rigorous one-year study from 2022 found no benefit to time-restricted eating, with participants losing no more weight than those who ate freely. The bottom line? Intermittent fasting is no more helpful than simply reducing daily calorie intake. Intermittent fasting is also not recommended for those who are pregnant, breastfeeding, have diabetes, or have a history of disordered eating.
And here’s what many people don’t know: Intermittent fasting affects men and women differently. Most studies on intermittent fasting that do exist have been completed with male subjects only, paying little attention to the potential effects on women and their hormone health. The results of those studies are then widely reported, generalized, and applied to female populations, without the study parameters being sufficiently detailed.
What the Science Shows
According to ZOE, some studies conducted on rodents indicate that intermittent fasting might alter estrogen levels, potentially impacting reproductive health aspects like fertility, menstrual regularity, pregnancy, and lactation. This is likely because hormone function in women, such as menstruating or lactation, requires more energy within the body. There’s also much anecdotal evidence that women have experienced changes to their menstrual cycle after intermittent fasting. If you lose your period while trying it, that’s a sure sign it’s not for you.
That’s because while men’s metabolisms may increase from short periods of fasting by up to 14%, women’s metabolisms tend to slow to conserve energy and store fat during famine. Our bodies respond to scarcity differently.
Other studies have shown that blood sugar levels actually worsened and insulin sensitivity had no improvement in women after intermittent fasting as opposed to their male counterparts. When calorie intake is low from fasting too long or too frequently, the hypothalamus in the brain is affected. This can disrupt the secretion of GnRH, a hormone that helps release two reproductive hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). When these hormones cannot communicate with the ovaries, there is an increased risk of irregular periods, infertility, and poor bone health.
What to Do Instead of Intermittent Fasting
Like any intense dieting plan, intermittent fasting isn’t always accessible (or safe) long-term. While intermittent fasting can disrupt hormone health and blood sugar levels, it can also feel rigid and unattainable for some of us. There are many ways to promote weight loss and overall health without the rigidity of fasting. If you’re looking to improve your health and nutrition, try these tips instead!
Eat Whole Foods: Eating foods that are minimally processed and in their natural state (think fruits and vegetables, lean meats, whole grains) can help promote healthy and sustainable weight loss by increasing metabolic rate. Whole foods also provide a good source of fiber, which can increase feelings of fullness and satisfaction after meals.
Prioritizing Protein: Aiming for (at least) 100 grams of protein each day is a great way to promote lean body mass AND keep your metabolism high. Protein intake increases the body’s thermic effect of food (TEF). Essentially, the body uses more energy (calories) to digest and process protein. So hitting your macro count for protein is SUPER important for promoting lean body mass. Most people think that intermittent fasting will benefit their metabolism, when in actuality, consuming more protein is much more beneficial.
Moving Your Body: While we all know that exercise is important, maintaining an active lifestyle outside of our daily lifting sesh is equally important for maintaining a healthy body weight. While our workouts help keep our body healthy, it’s important that we don’t sit on our couch for the rest of the day. Non-Exercise Activity Thermogenesis (NEAT) accounts for the energy that we expend doing daily life tasks, such as walking our dog, doing household chores, commuting to work, etc. Moving the body throughout the day is important for maintaining a healthy weight and active metabolism.
Get Sleep: Inadequate sleep levels can raise cortisol in the body, which makes it hard to lose weight. Aiming to get 7-9 hours of quality sleep keeps your body’s hunger cues in check and lowers insulin levels, keeping the body’s metabolism in check. For more tips on how to improve your sleep quality, read this.
The Bottom Line
While intermittent fasting is relatively new in the world of nutrition, there is a lot of conflicting evidence on whether it is healthy or just another diet fad. Though research on female participants doing IF is generally limited, experts suggest women approach intermittent fasting cautiously, particularly if they’re at an average body weight or BMI. In other words: Committing to intermittent fasting to lose a few pounds may not be worth it for your internal health and longevity.
We recommend speaking with your doctor before changing or restricting your diet in any way. Eating enough daily calories is not only imperative to achieving your health and fitness goals, but also to keep your bodily functioning optimally.
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