Written by Garett Reid | NSCA, CSCS, CISSN, M.S.E.S.S
Fact checked by Andrew Lenau, ISSA CPT & Sports Nutritionist
FACT CHECKED
Women's never-ending search for fast and effective weight loss has caused a ridiculous array of diets to be introduced over the years. Weight loss plans like the baby food diet, cookie diet, and tapeworm diet have all been marketed as potential weight loss plans designed to help ladies shed fat fast.
Plans like these have certainly given the term "diet" a bad name. But in reality, not all diets are as horrifying as swallowing a tapeworm. In fact, there are even a few that are effective, and when done correctly, have potential health benefits. One such diet is intermittent fasting for women.
Intermittent fasting has gained a lot of popularity over the past decade or so for its effectiveness and simple concept. Unfortunately, as effective as it may be, there's still plenty of misinformation that either exaggerates its effectiveness or downplays it. The truth is somewhere in the middle, and we're going to uncover it in this article.
This post will discuss:
- What is intermittent fasting?
- Different intermittent fasting protocols for women
- What to eat on an intermittent fasting diet
- Health benefits and risk factors
- Women-specific fasting concerns
A Brief Fasting History
The practice of fasting has been around for far longer than most of us think. In its traditional function, fasting was used as a way to show worship and adoration to a religion's God.
In fact, many religions still use fasting regularly, whether it's a part of Lent in the Christian faith or the month of Ramadan in Islam. Within this context, it symbolizes sacrificing your earthly needs to help focus your prayer and worship toward your God. Interestingly, the majority of studies that have been done on fasting were done by studying Muslims during Ramadan.
Interest in using fasting for weight loss dates back to the early 1900s, much earlier than many are aware of¹. There was even interest in the 1960s when a researcher named Bloom published a paper and introduced intermittent fasting as a treatment for obesity².
Modern Day Fasting
Similar to just about every other fitness phenomenon, meaningful public interest in fasting occurred years after studies showed benefits. For intermittent fasting methods, it was almost 50 years later, in 2012, when several key researchers and journalists introduced it to the general population.
At this time, intermittent fasting was not presented as a diet to lose weight but as an effective method to optimize total body health, including cognitive benefits.
Even with the interesting role that intermittent fasting has on brain health and cognitive function (we'll get into this below), its role in fat loss was highlighted, and the public loved it.
What Is Intermittent Fasting?
A major misconception about intermittent fasting that we'd like to clear up right away is that it's a "diet." In fact, intermittent fasting says nothing about your food intake and offers no guidance on things such as the best high protein low fat foods. While literature and dietitians will discuss the importance of eating nutritious foods instead of processed ones, intermittent fasting just assumes you will picky healthy foods, rather than making it a required guideline.
So what is it, exactly?
Intermittent fasting is an eating plan that has you alternate an eating window and fasting window throughout the day or week.
In the general population, a fasting window can last anywhere from 16-24 hours. During this time, you aren't supposed to consume anything with calories, not even liquids. This only leaves your eating window to consume food. This time will complement the fasting window, such as 16:8 or 20:4 (we'll discuss these windows more below).
To be clear, this does not mean you have 8 hours spread throughout the day to eat. These are blocks of time during the day, such as 10:00 am to 6:00 pm.
What Can You Eat Following Intermittent Fasting?
As mentioned above, you can eat whatever you want when following intermittent fasting. However, just because you can eat whatever you'd like, doesn't mean you should.
Generally, similar to when following a diet, like this cutting diet and workout plan, most people select healthier foods when fasting. The extent to which this occurs can vary widely from cutting out sugars to going on a completely raw diet. The main point is that an intermittent fasting "diet" allows you to choose what you eat.
Having this freedom is one of the reasons intermittent fasting for women is so popular. Not only can you eat the food you like, but there's also not a long list of foods you need to remember.
Still, we strongly advise you to at least follow a flexible-type eating plan, particularly if you're in it for weight loss. This includes:
- Concentrating on eating whole, "real" foods, like fruits, veggies, whole grains, and lean protein
- Limiting added sugar and processed foods
- Controlling your calories and macros (intermittent fasting is not magic!)
- Concentrating on lean proteins
- Choosing healthy fats
You can also pair a true diet with intermittent fasting, including plans such as the ketogenic diet, a low-carb diet, the metabolic confusion diet, the Mediterranean diet, or a vegan eating plan.
Intermittent Fasting Methods For Women
Intermittent fasting diets come in an array of protocols, some more or less suitable for goals such as weight loss and speeding up your metabolism. We will now go over the most common types.
1. Time-Restricted:
Time-restricted feedings are what more people think of when they think of fasting. In this model, every day has both an eating window and a fasting window.
Examples include:
- 16-hour fast and 8-hour feast
- 18-hour fast and 6-hour feast
- 20-hour fast and 4-hour feast
This is the easiest protocol to follow and is likely the most suitable for most women. For example, look at the 16:8 protocol. With this, you could eat from 11:00 am-7:00 pm. You're essentially just skipping breakfast and not snacking late at night. You're still able to prioritize what to eat before a workout and after a workout every day to hit your muscle-building goals.
If you are just entering the world of intermittent fasting, this is where you should start. Once you adapt, you can then prolong the fasting periods, if you want.
We highly recommend checking out our 16/8 intermittent fasting 7-day meal plan to help you get started. Interested in the 20/4 fasting option? Head to our guide on the 20/4 Intermittent Fast.
2. Periodic Prolonged Periods:
Periodic prolonged fasting involves eating your normal calories 5 days a week while fasting the other 2 days. As a warning, fasting for 24+ hours is exponentially harder than even 18 hours.
In terms of losing weight, we don't think this style of intermittent fasting for women brings any added benefit. Further, these more intense forms of fasting for women can have harsher side effects, such as complete diet failure or overeating on non-fasting days.
And for women athletes, not eating for two days severely limits your training protocol and makes it harder to crush your workout split. You don't want to go the whole day without eating on training days, and you also want to eat on your muscle recovery days.
3. Alternate Day Fasting:
Alternate-day fasting involves alternating fasting days with feast days. However, fasting days aren't true fasting periods, as you can eat 25% of your calorie intake.
Unfortunately, there isn't enough research on this style, but it sounds like an interesting method. If you want to follow this, we recommend you determine how much protein you need per day and concentrate on eating protein on your fasting days. For example, most people's diets are 25-35% protein, so you would almost be able to get 100% of your usual intake even on fasting days.
This means you'd still be able to support muscle mass even while your calorie intake is low.
4. 5/2 method:
The 5/2 method is similar to alternate-day fasting, except you only have two fasting days. On fasting days, you can still eat but with the same calorie restriction of 25% total calories. This method was actually the first method put forth in 2012.
5. Crescendo Method:
The crescendo method has you perform time-restricted fasting only 2-3 days a week. On two non-consecutive days, restrict your feeding window to 16 hours. While we don't see the sense in doing this long-term, it can be a useful way to dip your toes into the fasting pool.
Does Intermittent Fasting Help With Women's Weight Loss Goals?
There's a lot of confusion about intermittent fasting and whether it helps women lose weight. On the one hand, intermittent fasting definitely works and is an effective method to lose weight. This has been shown in numerous studies and meta-analyses³.
However, these studies can be misrepresented by the fitness industry to make it seem as though it's a weight loss cure-all no matter what. And that is simply not true.
The "Why" behind Intermittent Fasting's Effectiveness
There tends to be an inaccurate belief that intermittent fasting is a magic bullet. You may even come across a fitness influencer that claims you can eat whatever you want and still lose weight by offsetting your bad diet with intermittent fasting and things such as fasted cardio.
This is not the case. Now, we aren't saying anyone who claims this is lying. But we are saying that they're likely not looking at the whole picture. If you were to take 2,000 calories and limit yourself to an eating window of 4 hours, it would feel like you can eat whatever you want. You're eating 3-5 meals in one small time frame!
However, if you did manage to eat a surplus of calories within that window, you would still gain weight. This means that if you're planning to start a clean bulking plan soon, you could still technically do it while following intermittent fasting. But it could make things harder.
Something to keep in mind is that studies show that traditional diets and intermittent fasting are equally effective when calories are controlled. In fact, studies show that no diet is inherently better than the other if calories are managed⁴.
So when you lose weight on intermittent fasting, it's because you've reduced your calories. With weight loss, it all comes back to burning more than you eat.
Intermittent Fasting May Still Be Advantageous Compared To Other Diets
Unfortunately, life doesn't operate in the same sphere as laboratory studies. Of course, diets will contribute the same amount of fat loss if they put you in the same calorie deficit. However, it begs the question: Do some diets do that better than others?
Anecdotally, many women report being able to control their calories easier with intermittent fasting, meaning they can obtain a calorie deficit consistently. Having a strict eating window can play a huge role in your ability to cut out late-night snacking.
Intermittent Fasting May Decrease Cravings
Another anecdotal claim you may hear is that intermittent fasting decreases cravings, especially for sweets and processed foods.
Interestingly, there are studies that accompany these claims, yet the mechanisms aren't completely clear. For example, food timing seems to play a role as those who consume their food in the evening (shift workers) tend to be hungrier.
A study suggests that a traditional fasting diet that includes eating calories during the day improves the body's metabolic health, potentially helping you master your metabolism. As it does this, the body does a better jo of regulating hunger hormones, leptin and ghrelin⁵. Leptin is a hormone that prevents feelings of hunger, while ghrelin causes hunger.
Research has shown that ghrelin levels drop during intermittent fasting, but this does not occur on the first day. There are no studies on when this reduction in cravings may start but expect to put in at least 4 weeks before a notable difference occurs.
The study also notes that fasting might increase your metabolism, which would lead to greater calories burned. If all of this is true and you find it an easy protocol to follow, intermittent fasting may be the "best" diet for you.
Health Benefits Of Intermittent Fasting
So now let's get into other reasons why intermittent fasting for women might be a good idea. Remember, intermittent fasting for women can deliver much more than just weight loss.
Here are some of the best potential health benefits of intermittent fasting.
1. Improves Heart Health And Blood Pressure:
One of the major health benefits of intermittent fasting is heart health. And as having a healthy heart is vital for living a long and productive life, this is a major plus.
Studies have found that when a person follows intermittent fasting for prolonged periods, their heart health increases significantly. For example, a study examined the effects of using an alternate-day fasting plan on obese patients' cardiovascular health⁶. In 8 weeks, the participants saw improvements across several variables, including a 25% decrease in LDL cholesterol, a 32% decrease in triglycerides, and a 6% decrease in blood pressure and fat loss.
Now imagine if you paired intermittent fasting with LISS cardio. You'd have one ultra happy and healthy heart!
It should be noted that this benefit seems to be more prevalent in obese persons. But if you are worried about your heart health or suffer from high blood pressure, intermittent fasting may be a way to help treat the issues.
If you have low blood pressure, fasting will unlikely cause a further drop but check with your doctor if you have a history of health issues.
2. Improves Blood Sugar Levels And Controls Diabetes:
One of the most prevalent risks for overweight women (and men) is developing diabetes. When we eat, our bodies break down the food, resulting in blood glucose levels rising. For our bodies to absorb those sugars, insulin is released.
However, when someone becomes excessively overweight, whether they store their weight as back fat, chest fat, or even knee fat, they can develop insulin resistance, which is when the body no longer reacts to insulin levels in the same way as before. This can cause permanently high blood sugar levels that can eventually lead to an inability to produce insulin.
Interestingly, studies have shown that fasting diets can produce improve insulin sensitivity and decrease insulin resistance significantly.
3. Decreases Oxidative Stress And Cancer Risk:
Many chronic diseases are caused by increases in inflammation and oxidative stress. While not conclusive, intermittent fasting has shown signs of reducing both of these7,8.
Further, intermittent fasting has been shown to help prevent breast cancer in mice as well as mitigate the effects of chemotherapy9,10. More research needs to be done, but it's certainly promising.
4. Improves Brain Function And Acts As A Neuroprotector:
At the beginning of this article, we spoke about the initial rise of intermittent fasting in 2012 that included interest in brain health. Researchers believe this occurs through a variety of pathways including decreasing oxidative stress, promoting the growth of new brain cells, and increasing BDNF (brain-derived neurotrophic factor), which fights depression.
Studies have even shown the possibility of intermittent fasting being used to fight off neuro-degenerative diseases such as Alzheimer's and Parkinson's10-13. This is of special interest to women as they are more prone to these diseases.
Intermittent Fasting For Women Vs Men
The biology and physiology of men and women are different, which explains why things such as building muscle can vary between genders. For example, some different hormones and functions cause our bodies to react differently to the same situation.
In addition, women can be faced with different situations where the same rules don't apply, for example, during their menstrual cycle or pregnancy.
1. May Not Produce The Same Blood Sugar Control.
There is reason to believe that an intermittent fasting diet does not produce the same effects on women's blood sugar levels. This conclusion stems from a 2005 study that found blood glucose actually increased for 3 weeks in women14.
It's important to note that this occurred in non-obese women and during alternate-day fasting. It's also impossible to say the long-term effect on insulin sensitivity and insulin sensitivity.
So while this was the true result, it's difficult to make the broad statement that intermittent fasting increased blood sugar in women. Just be mindful, monitor it, and see your doctor if you are concerned.
2. Can Negatively Impact Women's Hormones And Menstrual Cycle.
Even though testosterone is generally thought of as a male hormone, women still have small quantities of these reproductive hormones that they must monitor. When testosterone or other androgen hormones rise, a condition known as hyperandrogenism can develop.
If this occurs, it can result in several unfavorable conditions, including increased fat, poor skin, and an irregular menstrual cycle.
Studies examining this condition and its relation to intermittent fasting found that when women eat their calories later in the day, they are at a greater risk15. Therefore, some scientists encourage women to keep their feeding window earlier in the day, before 4 p.m.
If you plan to shift your eating to earlier in the day, be sure to bump your chest workout (or any workout!) up earlier as well, so you can still eat a recovery meal after.
Intermittent Fasting For Women: Drawbacks And Risk Factors
There are several cons to consider before jumping into intermittent fasting. It's important to know the risks, and be sure to speak to your doctor prior to fasting if you have concerns.
1. May Put Women At Risk For An Eating Disorder:
Ladies are plagued with unsightly labels for areas susceptible to more weight gain, including saddlebags and hip dips. As a result, poor mental health and eating disorders are prevalent in our society and proportionately affect women. The two primary forms of eating disorders are:
- Bulimia: Periods of eating excessive amounts of food followed by self-induced vomiting.
- Anorexia: An obsession over weight and body image that leads to severely restricting calories.
Intermittent fasting resembles this disordered eating. If a woman begins to lose substantial body weight, she may be tempted to increase her fasting periods or calorie restriction. She may do the same thing if she doesn't lose weight fast enough.
Women with a history of disordered eating who re-try to diet put themselves at a much higher risk of relapse. In this case, you should absolutely speak with a counselor or doctor first if you want to try intermittent fasting.
2. Disrupts Social Life:
Food is a major part of social life in just about every culture. This can include family outings, hanging out with friends, and relationships.
If your fasting period begins early in the evening, nights out with friends can be difficult. If this would only be an issue for you on rare occasions, you don't need to worry about it, as eating outside your fasting period once in a while won't have any major effect.
On the other hand, if you're a social butterfly, you may run into problems. In this instance, there are two choices:
- Follow an alternate day fasting plan or the 5/2 plan.
- If following a time-restricted plan, move your non-fasting periods later (i.e., 3:00 p.m. to 9:00 p.m.).
The other major issue is alcohol. While you're allowed to drink (keep it to a minimum!), you'll be stuck going to happy hour your entire life following a traditional fast/feast schedule. As the same tips apply, you just need to consider this when planning your schedule. Adjust your fast and feast times so they better align with your lifestyle.
The point is that while you have more freedom regarding the foods you can eat, intermittent fasting can disrupt your social life. You'll have to decide if giving up some of your social life is worth the benefits that come with fasting.
3. Can Cause a Loss Of Muscle Mass:
Intermittent fasting is definitely not helping anyone put on more muscle mass and improve muscular strength. Even worse, there is a chance you could see a reduction in lean muscle mass.
This issue can arise from eating too few calories, which forces your body to turn to muscle instead of body fat for fuel. Under short periods of calorie restriction, your body will usually break down fat cells for fuel.
However, in times of increased stress or caloric needs, the body can break down that lean muscle mass you worked so hard to build. To mitigate this, practice the following guidelines:
- Always ease into a fasting diet. Don't automatically jump into a 24-hour fasting period immediately
- Be sure to consume all of your calories during your eating window.
- Don't follow intense training during your fast. If you do, plan on breaking your fast as soon as your training ends and eat.
4. Can Cause Mood Swings:
We've all had that awful hangry feeling, in which the only thing that will ease our crankiness is a large plate of protein French toast or any one of these mouth-watering muscle-building meals.
While intermittent fasting may help decrease your cravings eventually, it can take some time to adjust. Part of this process can include an increase in irritability, mood swings, and even less energy. This can be caused by simply being hungry but also an increase in cortisol, the stress hormone.
This is another reason we strongly recommend you begin your intermittent fasting journey slowly to allow an adjustment period.
Should Pregnant Women Follow An Intermittent Fasting Diet?
Before we answer, it's important you always check with your doctor before following any diet. However, when looking at the available literature, this is our best answer.
There seems to be a scarcity of research examining the effects of intermittent fasting and pregnant women. But one large review looked at these variables, specifically examining pregnancy during Ramadan.
The researchers found no negative effect on the mother or infant during pregnancy or birth16. The only drawback they noted was that some mothers had a reduced intake of calories or specific macronutrients. This seems to suggest that if you eat all your food, you should be good to go!
That said, if you haven't already been on an intermittent fasting schedule, your pregnancy is not a good time to start. Again, speak with your doctor or a private dietician before starting this while pregnant. Finally, whether it's through working out when pregnant or dieting, unless it is something you have discussed with your doctor, weight loss should not be top of mind when you're pregnant.
Intermittent Fasting: A Good Dieting Option For Long-Term Results
Intermittent fasting is a viable way to improve body composition and maintain a healthy weight. Its relatively easy protocol allows you to still eat foods you desire, making it a good choice for long-term adherence.
However, this is only possible if you understand how intermittent fasting works. We hope with the information you've just read, you're able to make an informed decision on whether intermittent fasting is for you.
Remember that there's more than one way to utilize intermittent fasting, so try experimenting with different protocols if you're interested.
Related:
References:
- Howard, A.N. (1975). Dietary Treatment of Obesity. In: Silverstone, T. (eds) Obesity: Its Pathogenesis And Management. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-7155-7_5
- BLOOM WL. Fasting as an introduction to the treatment of obesity. Metabolism. 1959;8(3):214-220.
- Stephanie Welton, Robert Minty, Teresa O’Driscoll, Hannah Willms, Denise Poirier, Sharen Madden and Len Kelly Canadian Family Physician February 2020, 66 (2) 117-125;
- Freire R. Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets. Nutrition. 2020;69:110549. doi:10.1016/j.nut.2019.07.001
- Patterson RE, Sears DD. Metabolic Effects of Intermittent Fasting. Annual Review of Nutrition. 2017;37(1):371-393. doi:10.1146/annurev-nutr-071816-064634
- Barnosky AR, Hoddy KK, Unterman TG, Varady KA. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. Translational Research. 2014;164(4):302-311. doi:10.1016/j.trsl.2014.05.013
- Cienfuegos S, Gabel K, Kalam F, et al. Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metabolism. 2020;32(3):366-378.e3. doi:10.1016/j.cmet.2020.06.018
- Jordan S, Tung N, Casanova-Acebes M, et al. Dietary Intake Regulates the Circulating Inflammatory Monocyte Pool. Cell. 2019;178(5):1102-1114.e17. doi:10.1016/j.cell.2019.07.050
- Brandhorst S, Choi IY, Wei M, et al. A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell metabolism. 2015;22(1):86-99. doi:10.1016/j.cmet.2015.05.012
- Longo Valter D, Mattson Mark P. Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism. 2014;19(2):181-192. doi:10.1016/j.cmet.2013.12.008
- Phillips MCL. Fasting as a Therapy in Neurological Disease. Nutrients. 2019;11(10). doi:10.3390/nu11102501
- Baik SH, Rajeev V, Fann DYW, Jo DG, Arumugam TV. Intermittent fasting increases adult hippocampal neurogenesis. Brain and Behavior. 2020;10(1):e01444. doi:10.1002/brb3.1444
- Bredesen DE. Reversal of cognitive decline: A novel therapeutic program. Aging. 2014;6(9):707-717. doi:10.18632/aging.100690
- Heilbronn LK, Civitarese AE, Bogacka I, Smith SR, Hulver M, Ravussin E. Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obes Res. 2005;13(3):574-581. doi:10.1038/oby.2005.61
- Cienfuegos S, Corapi S, Gabel K, et al. Effect of Intermittent Fasting on Reproductive Hormone Levels in Females and Males: A Review of Human Trials. Nutrients. 2022;14(11):2343. doi:10.3390/nu14112343
- Faris, Mo’ez Al-Islam E. and Al-Holy, Murad A. ‘Implications of Ramadan Intermittent Fasting on Maternal and Fetal Health and Nutritional Status: A Review’. 1 Jan. 2014 : 107 – 118.
Garett Reid
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