Intermittent Fasting for Women: Results and Effect on Women’s Health

Written by: Ioannis Nikitidis, MD, MSc

Many women try all sorts of diets but may not have considered intermittent fasting. But what is it, and how is intermittent fasting effective for women?

Put simply, it is when you go short-term periods (typically 12 to 24 hours) with no food, only water, and then eat a meal. Numerous studies show that not only weight loss results but also some important health benefits can be achieved when using intermittent fasting.

What intermittent fasting results women can expect: the answer from studies

There are many claims regarding whether or not intermittent fasting is good for women weight loss. And the only way to find out the truth is to take a look at scientific studies.

Study #1

This study compared two forms of caloric restriction in premenopausal women: Intermittent fasting and Continuous fasting. All women experienced modest weight loss, but we will focus on the results of intermittent fasting female group.

30% of the women lost between 5 and 10% body weight while 34% lost more than 10% in 6 months.

This means that the average intermittent fasting results during 1 month for females in that research were between 1,25% and 1.66% of their initial body weight.

During the study, the women were not counseled on exercise and there were no major changes in their physical activities. So, they could achieve even better weight loss results if they followed any kind of exercise program.

  • A few participants did experience headaches, coldness, lack of energy, and constipation.
  • 8 had hunger complaints while three claimed higher energy levels.
  • 8 also voiced negative psychological effects such as difficulties with food preoccupation, hostility, and poor concentration.
  • 17 proclaimed higher levels of self-confidence and better moods.
  • More female participants in the intermittent fasting group expressed difficulty implementing the strict diet requirements into their daily regimen. These results could only rely on the honesty of the subjects when keeping their diet diaries.

While the study examined weight loss and the psychological effects, it also looked at the physiological ramifications of things such as disease prevention in the areas of diabetes, breast cancer, and cardiovascular disease.

After measuring the risk markers from the start of the study and again at the end, scientists found that there was a reduction of those same markers, thus reducing the risks of being diagnosed with any of the above-mentioned diseases.

Study #2

Another study involved participants in an 8-week program of intermittent fasting along with calorie restrictions. This study explains that intermittent fasting consists of a dramatic reduction in the body’s energy needs between 75% and 90% on 1 or 2 days of the week.

In this trial on intermittent fasting results, women were asked to follow intermittent fasting for one day per week and eat a diet consisting of an energy (calorie) reduction of 20% the remainder of the week.

Participants lost about 4% of body weight during the study. The study also found that intermittent fasting in combination with calorie reduction was an actual means to reduce weight and body fat in the women.

It also lowered the risk of Coronary Heart Disease in areas like triglycerides and cholesterol. One of the two groups of the study also showed that using liquid meal replacements instead of food actually affected more weight loss as well as a greater reduction of the risk indicators of heart disease than the intermittent fasting diet with food.

Intermittent fasting and menstrual cycle

It’s worth remember that like any other form of calorie restriction, intermittent fasting can affect women’s health, hormones and menstruation.


Scientific researches show that prolonged and big calorie deficit created through too much exercise, and quick loss of body weight all may lead to different forms of menstrual dysfunction in women.

This is usually seen in women who are dieting for long periods of time as well as in female athletes who are not purposefully dieting, but unable to meet the caloric needs of their rigorous athletic regimen.

However, it’s not just prolonged periods of time in large calorie deficits that are the problem as having too little fat may be a problem for some women in itself. In 1974, scientists found that the maintenance of normal menstrual cycle was related to a critical level of 22% body fat.

Study on elite national level female athletes has shown that the combination of low body fat levels with a large calorie deficit can result in amenorrhea (absence of their monthly period), as well as deceased leptin and estradiol levels.

In this study 39 female athletes were examined.  The  leanest  women tended to be the ones who were amenorrhic, had the lowest levels of insulin, leptin and estadiol.

These women were roughly 23 years old, had a BMI of approximately 18 with a body fat level of around 15%. As an example, a 5’6” women in this study would weigh around 112 pounds, burn almost 1,000 calories per day through exercise, while eating around 1,700 calories per day and only 55 grams of protein per day.

The women who still had normal menstrual cycles had slightly more body fat (15.5%), the  same  amount  of  lean  mass,  but  ate  almost  500  more  calories a  day, and significantly more  protein  (55  vs  78  grams  per  day).  They  also  had  higher  levels  of leptin, insulin, thyroid hormones and leptin then their amenorrhic counterparts.

Even though these women were not fasting, this study shows that minimal levels of body fat, combined with long-term calorie deficits, and possible mild protein malnutrition can result in marked hormonal disruptions.

Intermittent fasting and women’s hormones

Another unique trait of women is their monthly fluctuations in estrogen hormone levels. These fluctuations may warrant consideration when dealing with both fasting and dieting as evidence from female studies indicate that food intake fluctuates during the menstrual cycle; it is lower in the periovulatory phase and greater in the early follicular and luteal phases.

Since  estrogen  is  known  to  depress  appetite  by  decreasing  sensitivity  to  food  cues, there may be periods of a month were women find intermittent fasting and dieting harder or easier, depending on their natural hormonal fluctuations.

So while there are definite recognizable differences in how women respond to intermittent fasting and dieting, there are no evidence to suggest that women should not fast.

This is not to say that women can haphazardly use as much fasting as often as they like in an attempt to lose weight. In fact, quite the opposite. This is more evidence that if intermittent fasting is to be used on a regular basis as a method of weight control then it must be done with some common sense.

Next you can read about women’s experiences of intermittent fasting that we received from Eat Stop Eat followers. Also, if you want to learn more why intermittent fasting works for women, read this post.


Naomi: “Many suggested keeping busy during a fast…”

I’ve always sworn I had hypoglycemia or some such and would faint if I didn’t get food, yada yada. This ruled my life. I have always eaten every few hours. There was a time I got myself 6 bagels every day and nibbled them throughout the day. I became very fit and athletic in my 20s and lectured anyone who didn’t run away that we were like a lamps and needed a constant source of fuel, carbs of course because that was the thing in the 1980s. If I went on an all-day outing with friends, I was stopping to nibble and snack all the time and felt that it kept me sane. Others agreed. Boy, did I have some growing up to do!

Every once in a while, I’d get convinced that fasting would be a good idea but I never made it very far and it always felt harder than running a marathon. I’ve also always gotten head rushes under certain conditions and now I think that heat and fasting make this worse but all it takes is standing up more slowly and pausing for a second, holding onto something if I need to. I tend to be hyper and leap up and race around so this little glitch is probably good for me.

When my friend first told me she was doing ESE style fasts, I dismissed her with all the usual arguments. I could never do that because I’m so special. I get dizzy. I have blood sugar issues. I have to eat every 3 hours. She didn’t say much, but thank goodness, she continued to tell me about it and she also continued disappearing before my eyes!

One day, I hit a plateau and the time was right to fast.

Sure enough, when I first started intermittent fasting, I had to be super gentle with myself and I actually acted like I had the flu the first few times. I just laid around, drank lots of water, did absolutely nothing at all, and still got a little dizzy and the beginnings of headaches. Every time I feel a bit of head pain come on, I drink a glass of water. This tends to stave it off for at least 20 minutes. Yes, I pee a lot when I fast!

Eventually, I looked at what others were doing. So many suggested keeping busy during a fast so I eventually ventured out and tried simple errands, then even managed grocery shopping and did NOT find I bought a lot of foolish stuff. I wasn’t starving; I felt clean and it was helpful to shop like this. I bought less, realizing I was eating less on those days and that, now I thought about it, no one else really needed to be eating quite as much as they were. And heck, I could shop again if I needed to; no need to cram the fridge and have it go to waste. Since starting fasting, I rarely waste any food at all. It’s pretty amazing, actually. I do shop more often.

Then I got really bold and tried working out fasted. At first, it was kind of awful. For a few minutes. Then I got a sort of a 2nd wind and felt great! And afterward, I felt like I could do anything! After a few weeks, I worked out regularly on fast days and it was a non-thought at the gym.

I just took a month off fasting, it’s killer hot and muggy here, and I have to say my first fasts were all like that again. Headaches. Dizzy, nausea on an unplanned fast to the point where I was going out of my way to get some food. But now I know I can fast so I worked through it and I fasted a bunch of days this week, headache is less and less each time, I pound water when it starts up. I feel certain the dizziness is just a warm weather thing. All this to say give it a chance. Try shorter fasts and/or staying in cool weather and/or being super gentle with yourself and always, always, pound the water!!!


Elisa: ” I feel slim, empty, and healthy…”

When I first started intermittent fasting it was hard as hell. I did my first 24 hour fast (dinner-dinner) on a Thursday. The hunger pangs that first day were tremendous. I was somewhat OK until about early afternoon. Then the pangs set in. They would hit about every half an hour or so. I would steel myself whenever they hit and just think “this is worth it”. I really hoped that this would get better in the future (like the other experienced fasters were saying). I thought I wouldn’t be able to continue to fast if it always felt like that.

I fasted two more times in the next seven days (because I was desperate to get off a plateau I had been on, and I tend to be an all or nothing kind of person). They were hard too, but not as hard as the first day and I was progressing which made it bearable. After that, I averaged around two fasts a week, on top of staying low in calories on my off days (1000 cals/day is what I aim for). It took about 3 weeks before I noticed a difference in the way I felt on this reduced calorie regimen, meaning it took this long before it started feeling much easier and the pangs pretty much went away.

I do mainly 24 hour fasts, but have completed two 36 hour fasts also, including one I just did yesterday and broke this morning. In the past few weeks, I have only been fasting about once a week. At this point, I almost prefer the 36 hour fasts as I know I don’t have to worry about food all day long. And because my stomach has adjusted to the low cals, I can go all day now with NO hunger pangs. I still feel hungry…but the actual pangs are gone. Last night, I felt the glimmer of a pang a couple times around dinner time, but I really think that it was psychological in nature. Kind of like my body was saying, “I’m gonna getcha”, but then had to back down once it realized I wasn’t going to give in.

Now, if I go on a bender and my cals go back up every day for a period of time, I don’t know if fasting would feel so easy any more. I have my mini binges, at times, but they have not affected the fasts. I have not gone on any “benders”. Some women have, and they report that it is harder to fast after this happens. Probably because the stomach has stretched out again and has become accustomed to more cals. In a few weeks, my husband is coming back from a deployment and I will not be eating low cal for about two weeks. I will see then what a return to fasting will feel like.

What I love about the 36 hour fasts is the feeling I have in the morning when I wake up. I feel slim, empty, and healthy. I’m never hungry first thing in the morning, so I can take my time to figure out what I’m going to do to break the fast. I was up for around an hour and a half this morning before I had a cup of hot tea with honey and cream.

Anyway, my point with all this, is that IT WILL GET EASIER. Not easy all the time, but definitely easier.


Mari: ” It didn’t have any of the effects I’d feared…”

Reading through the forums and blogs, I finally decided to buy EatStopEat, which I did 2 days, read 37 pages, and woke up yesterday morning deciding I was going to try a 24-hour fast. I’d eaten at 7:00 the night before, so I made a cup of coffee, and spent the day counting the hours until I could eat.

I’ve never fasted before. Ever. So while I KNEW I’d be able to do it, I just wasn’t sure what to expect…was I going to feel faint? Was my head going to hurt? Were my legs going to give out from starvation (uh, yeah, I have 100 lbs to lose…I don’t think “starvation” is really a problem…)? I decided not to work out yesterday because I didn’t want to push my luck, plus I’d worked out the 4 days prior.

I’ve been diligent about the 12-16 hour fasts since I started a week ago. It made sense to me that if I could prolong my need to eat, I’d be able to budget my calories more easily during the remainder of the day. But the part that was more of a mind blow that made me have my first “A-ha Moment” was considering fasting as part of that same calorie budgeting plan. So rather than my 7800 weekly calorie budget being spread across 7 days (including an Eat Up day), I could spread it across 6 days.

I was struggling because my Eat Up day last week was my first day…kind of backassward, but it’s just how things ended up. So I decided I may as well try a fast. And last night I had 849 calories left so I indulged myself in a beef brisket burrito on a whole wheat wrap with guacamole, veggies and Sriracha sauce. I had enough calories left over for half of a Wholefoods caramel apple. My second “A-Ha” moment was how happy I was with that satiated feeling of eating a larger meal, still within my calories (with a few to spare), and including a “treat” I hadn’t expected to be able to have.

I don’t need to feel that kind of full all the time. I know we are trying to learn proper portion sizes and how to limit our intake so we can make this a lifelong AND lifestyle change. BUT. I really needed to feel that fullness. I can’t explain the feeling of contentment it gave me to chomp through that burrito and then a gooey dessert and feel full – not Thanksgiving full, but full nonetheless. There was a psychological trigger that pulled when I had gone through the effort of not eating, so when I finally DID eat, the reward was immense.

My take-aways & observations from my first 24-hour fasting experience?

1. use the window from dinner to dinner as my fast time; it’s much easier for me to get through the day knowing I will have dinner rather than going to sleep hungry.

2. I was ok most of the day, it didn’t have any of the effects I’d feared (headaches, depleted energy). My stomach did start to growl like the Maw of Hell resided within it at one point in the afternoon, but it eventually quieted down.

3. I had the hardest time in the last 1 1/2 hours of my fast. I started lagging and felt a little sleepy. Once I ate this went away.

4. I had an odd gassy moment right before it was time to eat. I wondered what triggered it since no food had passed my lips for 24-hours. I don’t tend to be a super-tootie person, so it was worth noting. My kids thought it was hilarious.

5. I need to finish the book, but reading Pilon’s email newsletters has given me even more insight as to how fasting may very well jump start my weight loss in a big way since I have so much weight to lose.

6. Eating to fullness is something I like the feeling of for some reason. Not every time, but it felt like a reward after a fast and I realized it made me feel weirdly happy. And because I had that emotional response, it’s something I need to pay attention to because it will probably come up again, maybe with stress eating. And this might help me manage that.


WomenLadies, click here to discover the simplest and scientifically proven style of intermittent fasing that make you forget every other unrealistic super-complicated weight loss and diet program.


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