Intermittent fasting is everywhere right now, much like diet pills were in the ’90s, so chances are you’ve heard the buzz and maybe even thought about trying it yourself. But before jumping in because it worked for someone else, it’s worth taking a closer look. There are several approaches to intermittent fasting, and depending on your lifestyle, age, and health history, it may, or may not, be a good fit (1).

While research shows potential benefits in areas like weight management, insulin regulation, and inflammation, it also highlights important cautions, especially for those navigating a history of disordered eating (1). Women’s health is nuanced, and our hormones add another layer of complexity, making a one-size-fits-all approach unrealistic (1).

That’s where this guide comes in. We’ll explore what the science says about its impact on women’s health and share considerations to help you decide if intermittent fasting is the right approach for you. 

Understanding Intermittent Fasting and How It Affects Women

Intermittent fasting types may vary, but at its core, each approach follows the same idea: setting specific windows of time for when you eat to allow your body time to rest (1). The most common intermittent fasting approaches are:

• The 16:8 Method: You eat within an 8-hour window each day, and allow your body to rest without food the other 16-hours (1). 
• The 5:2 Method:  This involves 2 non-consecutive days of fasting (or significantly reduced calorie intake under 500 calories a day) alongside a balanced, regular eating pattern on the other 5 days (1).
• The 12:12 Method: This involves eating within a 12-hour window, and fasting the other 12-hours. This often is a gentler approach to beginning intermittent fasting for beginners (1). 
• Circadian Rhythm Fasting: Also known as time-restricted eating, this style of fasting follows the natural flow of your body, allowing eating usually to occur in a 6- to 10-hour window during daylight hours, followed by a fast during the night (2). 

Fasting can affect women differently than men, largely due to differences in hormone regulation (3). In women, factors like age and life stage play an important role in how the body responds to periods of fasting, particularly when it comes to reproductive hormones (3,4).

Some research suggests that fasting may offer benefits in specific cases. For example, research suggests it may help improve menstrual regularity and fertility in women with polycystic ovarian syndrome (PCOS) by supporting hormonal balance (3). On the flip side, concerns remain on the impact intermittent fasting has on reproductive and bone health, fat free mass, eating disorders, and sleep (5). That said, more research is needed to better understand these effects.

With that in mind, it’s worth taking a closer look at the potential benefits of fasting for women approaching 40, as well as the life stages where it may not be the most appropriate approach.

Benefits of Intermittent Fasting for Women Over 40 

When we look at the research, the benefits of intermittent fasting for women really seem to shine for women as they enter the transition to menopause, which usually occurs sometime in their mid-40s (6,7). During this period, women’s hormones change rapidly, with estrogen and progesterone declining. With these changes, the way women use energy also changes (7). Most women report experiencing body composition changes that leaves them wondering why what worked for them before may not be working for them now when it comes to managing body weight (7). 

With this in mind, here’s some of the science-backed reasons intermittent fasting may be worthwhile for some women over 40. 

• Weight and body composition management. 

Many women experience changes in weight and fat distribution due to declining estrogen levels around menopause (6,7). Some research suggests that intermittent fasting, particularly time-restricted eating, may help reduce visceral fat and improve metabolic markers like blood sugar and lipid levels by supporting insulin sensitivity (6). This makes it a potential tool for addressing menopause-related weight changes.

• Heart health support.

The transition to menopause can also naturally increase cardiovascular risk as estrogen levels drop (6). Early research shows that intermittent fasting may help support heart health by improving LDL cholesterol levels, blood pressure, and blood vessel function, factors that contribute to long-term heart-health (6).

• Improvement in cognitive health. 

Declining estrogen levels during menopause can also affect brain function and may increase risk for cognitive decline (6). Fasting has been shown in early studies to support the production of brain-derived neurotrophic factor (BDNF), a protein linked to brain health long-term (6). While promising, more long-term research is still needed in this area.

• Potential reduction in inflammation.

Menopause is often associated with increased inflammation, which can contribute to conditions like joint discomfort and bone loss (6,7). Intermittent fasting may help reduce inflammation and lower oxidative stress in the body (6).

• Simplified eating structure for some women.

It’s also important to recognize the mental load many women carry in midlife. MyFitnessPal dietitian Brookell White shares, “For some, a structured eating window can simplify daily decisions, reduce meal planning fatigue, and feel like one less thing to manage, potentially easing overall stress.”

When Women Should Avoid Intermittent Fasting 

Fasting isn’t for everyone, let’s make that crystal clear. In fact, research shows fasting can have detrimental effects for women if you fall into one of these categories (1): 

• Have Type 1 Diabetes
  • Those with type 1 diabetes are at greater risk for hypoglycemia, making fasting off the table if you have this (1). Balanced intakes and close control of insulin management is key. 
• Have a History of Eating Disorders/Disordered Eating
  • Disordered eating and fasting do not mix well. Combined with the restriction mentality and obsessive thoughts that can come when eating windows are decreased, it’s advised not to consider this style of eating if you have a heightened preoccupation with food (1). 
• Those with Low Bone Density / Weakened Immune System 
  • Nutrient intakes can suffer when following intermittent fasting, meaning if you fall under one of these two categories, it’s advised to skip the fast and focus on meeting your nutritional needs in a regularly planned and balanced meal plan (1). 
• Those Trying to Conceive
  • Hormone regulation is crucial if you’re trying to conceive . Unless under advice from your reproductive health team for managing conditions like PCOS, it’s advised to focus on balanced, healthy eating patterns when trying to conceive (3). 
• Women Who Are Pregnant 
  • Intermittent fasting is generally not recommended during pregnancy as it can pose risks to the baby and mother (1). Consistent nutrient intake is necessary for healthy growth and development for mom and baby (1).
• Women Who Are Breastfeeding
  • Fasting while breastfeeding is not recommended due to risks of decreased milk production and nutrient deficiencies (1). Baby (and mom) have increased nutritional needs during this time to support proper growth, development, and recovery. 

How Women Can Start Intermittent Fasting Safely

If you’ve been given the green light by your healthcare team to start intermittent fasting, then consider these tips to set yourself up for success.

1. Start with a shorter fasting window. Naturally aligning your eating to your wake hours is a great start. While harder in winter months depending on where you’re located, aim to have your first meal within 1-2 hours of waking when the sun is rising and the last meal at least 2-hours before you wind down for the night. If you’re logging 8-hours of sleep, this will allow for a nice 10 to 12-hour fasted window. 

2. Prioritize nutrient-dense foods during eating windows. Whole foods with a focus on lean protein and fiber, should be the base of your meals (8). Foods that contain these help with satiety, and provide antioxidants, and other important vitamins and minerals. Dairy foods work well as protein sources, like Greek yogurt, while also providing calcium for bone health (6,9). Salmon is an excellent protein source too that also provides vitamin D and healthy fats, like those omega-3s that support brain health (6,10). And, don’t skip out on the plant-proteins like soy and legumes. 

3. Pay attention to how fasting interacts with your cycle. Feeling fatigued and worn out? You may not be eating enough to support your energy needs. Consult with a healthcare professional to figure out what you need to help support your body. 

4. Avoid exercising fasted if energy and performance suffer. You know your body best. Injuries can happen if you are running on empty. Plan your workouts around your eating windows to get the most out of your training. 

5. Pay attention to signs if fasting isn’t working for your body. Hormonal changes, mood shifts, sleep disruption, or cycle irregularity are signals worth taking seriously.

6. Rely on helpful tools.  Apps can have special tools to support intermittent fasting like MyFitnessPal’s intermittent fasting feature. They may help take the guesswork out of your eating windows, making it easier and more enjoyable to stick to your fast. 

Bottom Line

Intermittent fasting can be a useful tool for some women, but it’s not a universal solution.  Life stage, hormonal health, and individual response all matter. If you’re considering intermittent fasting, it’s important to approach it with curiosity rather than rigidity, tuning into your body.  Tracking how you feel and what you’re eating is a good idea to stay informed about how your intakes are stacking up in meeting your nutrient needs. 

Curious how others are approaching fasting? Join the discussion in our MyFitnessPal community forum. Remember, the best results happen when you speak with your own healthcare provider before making significant changes, especially during hormonal transitions.

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