Intermittent fasting, also known as IF, has become a popular method for getting lean and losing weight. It’s also said to boost energy levels, increase motivation and stamina, and improve cognitive function. Those benefits don’t sound too shabby, do they?

While intermittent fasting does seem to offer some promising benefits, it may not be for everyone — especially depending on whether you’re male or female. And as it stands now, there’s more research being done on intermittent fasting for rats than for humans.

It seems that whether or not intermittent fasting will work for you comes down to human biology. While shorter periods of fasting are generally considered safe for most people, some of the extended fasting times associated with intermittent fasting aren’t recommended for women.

Before we get into the details, let’s look closer at what intermittent fasting is, how it works, and the pros and cons of this eating trend for women.

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What is Intermittent Fasting and How Does it Work?

Intermittent fasting may sound a bit technical, but you’ve probably done it before without even realizing it. First, it helps to know the difference between the fasted state and fed state.

The Fasted State vs. Fed State

When you eat every few hours, you’re in a “fed” state, which is when your body is busy digesting, absorbing, and assimilating the nutrients from your meals. Accelerated fat burning isn’t the #1 priority here. Most of us remain in the fed state during the day, aside from when we’re sleeping.

The reason why intermittent fasting can provide certain benefits for weight loss is because it allows your body to enter the fasted state, which is when your body’s fat burning can really accelerate.

How Intermittent Fasting Works

Intermittent fasting simply means you go a period of time without eating, usually between 12 to 48 hours. This length of time is known as your fasting window, during which time you only consume liquids, such as water, herbal tea, or broth.

Some experts recommend drinking low-calorie green vegetable juices and taking supplements while fasting to help keep vitamin and mineral intake consistent, while others believe only water should be consumed. Like many topics in the health realm, the rules around intermittent fasting are subjective, depending on who you ask.

If you fast for less than 24 hours, you’ll also have an eating window. This is the time allotted for meals before you begin your fast. For most people practicing intermittent fasting, their eating window is between six to 12 hours. The most common fasting times are 12,14,16, and 18 hours.

For example, if you were to do a 12-hour fast, your eating window would be 12 hours. You could start your eating window at 7am and end at 7pm. You would break the fast the next day at 7am.

Although some of the intermittent fasting methods online seem more intense than others (some can last upwards of 48 hours), the beauty of intermittent fasting is that you get to choose and experiment with how long you fast. This not only allows you to determine how intermittent fasting can fit in within your lifestyle, but to discover the fasting sweet spot that helps you feel best physically.

Pros and Cons of Intermittent Fasting for Women (And Why it Can Be Tricky)

Some of the benefits of intermittent fasting may include:

Sustainable weight loss

An increase in lean muscle mass

More energy

An increase in cell stress response

A reduction in oxidative stress and inflammation

Improvement around insulin sensitivity in overweight women

Increased production of neurotrophic growth factor (which could boost cognitive function)

Now, here’s the tricky part. Although intermittent fasting may have its benefits, women are naturally sensitive to signs of starvation, so intermittent fasting for women is a whole different beast.

When the female body senses it’s headed towards famine, it will increase the production of the hunger hormones, ghrelin and leptin, which signal the body that you’re hungry and need to eat ( 2 ). Additionally, if there’s not enough food for you to survive, your body is going to shut down the system that would allow you to create another human. This is the body’s natural way of protecting a potential pregnancy, even if you’re not actually pregnant or trying to conceive.

It’s not that you’re intentionally imposing a famine upon yourself — but your body doesn’t know that. It doesn’t know the difference between true starvation and intermittent fasting, which is why it defaults to this protective mechanism.

Therefore, some of the cons due to hormonal imbalances brought on by intermittent fasting may also lead to:

Irregular periods (or complete loss of period)

Metabolic stress

Shrinking of the ovaries

Anxiety

Fertility issues

Difficulty sleeping

Since all of your hormones are so deeply interconnected, when one hormone is thrown off balance, the rest are also negatively impacted. It’s like a domino effect. As the “messengers” that regulate nearly every function in your body — from energy production to digestion, metabolism, and blood pressure — you don’t want to disrupt their natural rhythm.

With all of these drawbacks, you may be wondering: could you (and would you still want to) practice intermittent fasting as a female? If you take a more relaxed approach, the answer is yes. When done within a briefer timeframe, intermittent fasting may still help you reach your weight loss goals and provide the other benefits previously mentioned, without messing up your hormones.

The Best Intermittent Fasting Methods for Women

So, what exactly is a relaxed approach to intermittent fasting? Again, since there’s little research done on intermittent fasting, we’re dealing with a bit of a gray area. The opinions also tend to vary depending on which site you visit, or which health expert you ask. From what we’ve found, the general guidelines to brief intermittent fasting for women are:

✅ Do not fast for longer than 24 hours at a time

✅ Ideally fast for 12 to 16 hours

✅ Do not fast on consecutive days during your first two to three weeks of fasting (for instance, if you do a 16-hour fast, do it three days a week instead of seven)

✅ Drink plenty of fluids (bone broth, herbal tea, water) during your fast

✅ Only do light exercise on fasting days, such as yoga, walking, jogging, and gentle stretching

Options for Intermittent Fasting

There are several different intermittent fasting methods discussed online. Here are a few of the most popular ones.

Crescendo Method

The Crescendo Method is one of the best ways to ease into intermittent fasting without shocking your body or aggravating your hormones. It doesn’t require you to fast every day, only a few days per week, spaced throughout the week. For example, Monday, Wednesday and Friday.

Fasting Window: 12-16 hours

Eating Window: 8-12 hours

Safe for Women: Yes

16/8 Method

The 16/8 method, sometimes called the “leangains method,” is another brief intermittent fasting routine that’s used specifically to target body fat and improve lean muscle mass (a.k.a. your gains!).

Fasting Window: 16 hours

Eating Window: 8 hours

Safe for Women: Yes

24 Hour Protocol (a.k.a. “Eat-Stop-Eat”)

The 24 hour protocol, also known as “eat-stop-eat” requires you to do a 24-hour fast, once or twice a week. You can choose the time you start fasting. Some people prefer to fast from 8pm to 8pm the following day, or begin their fast after breakfast.

Fasting Window: 24 hours

Eating Window: 0

Safe for Women: Yes, when done a maximum of 2 times per week.

The 5:2 Diet

The 5:2 diet, also known as the “Fast Diet,” involves restricting calories two days a week to 500 calories per day (with two 250 calorie meals), while eating normally for the other five days. For example, you might eat all of your regular meals Saturday through Wednesday, and eat 500 calories per day on Thursdays and Fridays.There isn’t a ton of research to back up this diet, although it was publicized by Michael Mosley, a British journalist and doctor. Since it doesn’t completely restrict food on the fasting days, it may also be an effective way to ease into fasting without shocking your system. The Fast Diet is considered safe for men and women.

Fasting Window: No fasting window, just calorie restriction to 500 calories per day for 2 fasting days per week

Eating Window: Assume regular caloric intake 5 days per week

Safe for Women: Generally considered safe for women, but studies are lacking on this diet

Method Eating Window Fasting Window Safe for Women? Crescendo Fasting 8-12 hours 12-16 hours Yes 16/8 Method 8 16 Yes The 5:2 Diet Regular meals 5 days per week 500 calories per day for 2 days per week Generally yes

When Should You Avoid Intermittent Fasting?

Intermittent fasting isn’t a good fit for everyone. You shouldn’t consider intermittent fasting if you are:

Pregnant

Nursing

Under chronic stress

Have a previous history of eating disorders

Have difficulty sleeping

Additionally, intermittent fasting is meant to complement a healthy diet and lifestyle — not act as a way to remedy five days of eating nutritionally-bankrupt foods, such as refined sugar, processed foods and fast foods.

Final Thoughts on Intermittent Fasting for Women

Intermittent fasting may work amazingly well for some people, and terribly for others. Most importantly, if you do decide to give intermittent fasting a try, be sure to listen to your body’s feedback. Easing into intermittent fasting by starting with shorter fasting windows can help with initial symptoms of hunger and discomfort. But if it becomes too uncomfortable, be honest with yourself, accept it, and move on.

At the end of the day, nothing can have a greater impact on your health than a diet consisting of real, whole foods, and a lifestyle that prioritizes your physical, mental, and emotional well-being.