Why Intermittent Fasting Works for Some Women and Backfires for Others

Intermittent fasting is one of those topics that can feel really confusing in perimenopause.

Some women swear by it.
Others try it once and feel shaky, exhausted, anxious, irritable, and completely miserable.

Both experiences can be true.

I personally believe intermittent fasting can be a very powerful healing tool, but things become a little more complex when hormones start changing during perimenopause.

My Personal Experience With Fasting

When I first started my health journey, intermittent fasting was one of the easiest ways for me to lose weight.

Back then, I started by skipping breakfast and eating lunch later in the day.
That’s also when I developed my love for black coffee. 

I used to drink coffee loaded with creamer. I always joke that I basically had coffee with my creamer instead of creamer with my coffee.

But once I learned that calories and sugar break a fast, I switched to black coffee because I loved coffee too much to give it up completely. And now? I actually prefer it that way.

Fasting also helped me cut down on sugar cravings in the morning, which made a huge difference in my energy and appetite.

Why Fasting Feels Terrible for Some Women

Now here’s the part people don’t talk about enough:

Men and women are very different when it comes to fasting.

My husband can go on these extended fasts and feel completely fine.

Meanwhile, if I push things too far, I’ll end up with headaches, irritability, low energy, or feeling overly stressed. And that’s because women’s hormones are much more sensitive, especially during perimenopause.

So if you’ve tried fasting before and ended up feeling shaky, obsessed with food, exhausted, anxious, emotional, or unable to think about anything except your next meal, you didn’t necessarily “fail” at fasting. More often than not, it’s a sign that your body may not have been properly supported beforehand, especially when it comes to blood sugar balance, stress levels, sleep, and getting enough nutrients.

What Intermittent Fasting Actually Is

One thing I want to clear up right away is this: Intermittent fasting is not starving yourself.

And it’s not randomly skipping meals all day long. At its core, fasting is simply giving your body a break from constantly digesting food. One of the most common forms is called time-restricted eating, where you shorten the eating window during the day and extend the overnight fast.

For example:

• finishing dinner around 7 PM,

• then not eating again until 7 AM or later the next morning.

That simple overnight break can actually be incredibly supportive for the body.

Why Fasting Can Be Helpful

When fasting is done correctly, it can help stabilize blood sugar, improve energy, reduce inflammation, support mental clarity, improve metabolic health, and help the body access stored energy more efficiently. One of the biggest reasons people tend to feel better with fasting is because it helps calm the blood sugar roller coaster. And if you know me, you know I talk about blood sugar a lot. 

Honestly, so many women are struggling with unstable blood sugar and don’t even realize it, and it impacts everything from energy and cravings to mood, anxiety, and brain fog.

The Blood Sugar Roller Coaster

If you constantly:

• crave sugar,

• need snacks every few hours,

• feel shaky if you don’t eat,

• crash in the afternoon,

• feel irritable,

• struggle with brain fog,

• or feel anxious…

there’s a good chance your blood sugar is all over the place.

One of my favorite explanations comes from Dr. Jason Fung, who compares your cells to a packed subway car.

Imagine glucose (sugar) trying to squeeze into an already overcrowded subway. Insulin acts like the conductor trying to shove more people inside. Eventually the subway gets so packed that there’s nowhere else for the sugar to go, so it starts backing up into the bloodstream.

That’s essentially what happens with blood sugar overload and insulin resistance.

And one of the benefits of fasting is that it allows your body time to use up stored sugar for energy instead of constantly adding more fuel on top of fuel.

Why Fasting Can Backfire in Perimenopause

Here’s where things get tricky for women over 40. During perimenopause, hormone production begins shifting from the ovaries to the adrenal glands, and the adrenal glands are also responsible for managing stress. So now the body is juggling hormonal shifts, chronic stress, cortisol, poor sleep, unstable blood sugar, caffeine, emotional overload, and then many women add aggressive fasting on top of all of it. 

It’s no wonder so many women feel awful. When the body already feels overly stressed, it can start interpreting fasting as another threat instead of a healing tool.

And that’s when symptoms like:

• anxiety,

• fatigue,

• belly fat,

• sleep issues,

• irritability,

• mood swings,

• and brain fog

can actually worsen.

Why I Prefer a Gentle Fasting Approach

Over the years, I’ve actually changed the way I personally fast.

I used to do longer fasting windows in the morning, but now I focus more on:

• finishing dinner earlier,

• giving my digestion a break overnight,

• and supporting my sleep.

That approach feels much more supportive for my body right now and this is the approach I take with women inside the Hormone Reset Project, too.

We start gently. No extreme fasting. No trying to “power through.”

Most women simply begin with a 12-hour overnight fast.

That alone can be incredibly beneficial for digestion, hormones, sleep, blood sugar, and overall energy levels. Giving the body a simple overnight break from constantly digesting food allows it time to rest, repair, and function more efficiently, which can make a big difference in how women feel during perimenopause.

One of the Biggest Mistakes Women Make

One of the biggest mistakes I see women make is accidentally breaking their fast without realizing it.

Things like:

• sugary coffee creamers,

• sweetened drinks,

• flavored electrolytes,

• or snacks during the fasting window

can trigger insulin and interrupt the fasting process.

And then women feel frustrated because they think fasting “isn’t working.”

Why the Balanced Plate Method Matters So Much

This is also why I always emphasize the Balanced Plate Method alongside fasting. Because if you fast all morning and then break your fast with sugary foods, processed carbs, not enough protein, or meals lacking nutrients, you’re right back on the blood sugar roller coaster again. 

When you do break your fast, your body needs protein, fiber, healthy fats, and nutrient-dense foods to help you feel stable, energized, satisfied, and supported instead of crashing shortly after eating.

Fasting Is Not One-Size-Fits-All

One of the biggest things I want women to understand is fasting is not one-size-fits-all.

Some women do very well with it.
Others need to go much slower.
And some women should avoid it altogether.

For example, fasting may not be appropriate for:

• women with a history of eating disorders

• women who are underweight

• pregnant women

• or women dealing with significant adrenal stress.

This is why listening to your body matters so much.

Start Simple

If you’re curious about intermittent fasting, I encourage women to keep it simple at first.

Start with:

• a 12-hour overnight fast

• balanced meals

• enough protein

• stable blood sugar

• and paying attention to how your body responds.

You do not need to jump into a 16-hour fast immediately.

In fact, for many women, that’s too stressful right away.

The Next Step 

If fasting made you feel terrible in the past, please know that you likely needed more support first. That’s why I believe women in perimenopause need a much gentler, more supportive approach to health overall… less punishment, restriction, and “pushing harder,” and more nourishment, nervous system support, blood sugar stability, quality sleep, and learning how to listen to your body. Because your body is not working against you, it’s asking for more support. 

Hi there, I’m Jenny

I’m a Board Certified Functional Medicine Health Coach, podcast host, wife, mom of two teens, and lover of nature, farmers' markets, and a really good cup of coffee.  After struggling with weight gain, anxiety, low energy, and brain fog after turning 40, I discovered a simpler, more sustainable approach to health through functional medicine and lifestyle changes. Now, I help women over 40 navigate perimenopause with realistic strategies that support hormones, energy, mood, sleep, and confidence, so they can finally feel like themselves again.

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