In the interest of full disclosure, I admit that I am not very knowledgeable about this topic since I am a man. I have, however, done some research into this myself and I feel I have gotten the gist of what the consensus is on this topic. However, do NOT take my advice as fact, nor should you take it over a medical practitioner’s advice.
If you are a woman and wish to attempt IF, I highly suggest you schedule regular check-ups with your doctor as this can impact your health negatively.
First, men and women probably shouldn’t fast for the same amount of time.
Even Martin Berkhan, founder of the LeanGains 16/8 fasting and weight training protocol, recommends that women should fast for a shorter period of time, namely 14/10 (that’s 14 hours fasting, 10 hours feeding window).
He explains that women have “lower plasma glucose concentrations than men after the same time spent fasting” and this leads to a higher chance of women feeling “moody and hungry if they go too long without feeding”. On the other hand, men can fast much longer without feeling those same effects.
Some women have complained about experiencing negative effects while fasting. They have experienced such effects as: migraines, irregular or loss of periods, symptoms of polycystic ovary syndrome (PCOS), dizziness, and water retention just to list a few.
However, there are women who have experienced no positive or negative effects from IF. There are also women who have succeeded with IF by shedding the pounds and experiencing little, if any of the side effects. The range of successes and failures are across the spectrum.
Some women simply ate more carbs, some ate more fats. Others decided to fast for a shorter period of time, others are fine fasting for 20 hours.
Some have mentioned specific foods that are triggers: eggs, onions, garlic.
Some have mentioned that simply switching when they break their fast was all that they needed. For example, if they felt hungry in the morning but usually broke the fast in the afternoon, then the simply listened to their body and broke their fast when they felt they needed to.
The problem with the paragraph above is that if you are simply eating whenever you want, then are you really even doing IF? I suppose when you do feel hungry, eating a large meal that will satisfy you for a long time and again near the end of the feeding window (after 10 hours in this case) might be beneficial. This would perhaps help with feeling more full and therefore diet compliance.
There are also other variables that women have tweaked which have solved their fasting problems, however I see no consistent pattern. Thus, I can only conclude very broadly: listen to your body. Take note of what you naturally desire during the fast and see what happens to your symptoms if you listen to your body. Then see if you can still make IF work with this condition.
My approach to this issue:
If I were a woman who wished to commit to intermittent fasting, I would approach this very cautiously – by easing myself into longer periods of fasting instead of doing it cold turkey. I’d probably start off with 9 hours of fasting (an easy starting point if you sleep for 8 hours and then wait 1 hour before eating breakfast). Then I’d increase that to 10 hours. Then 11, 12, all the way up to 14 hours (as recommended by Berkhan).
Should there be a particular food that I’m craving, I’d take note of it. I’d also wonder: what macronutrients does that food consist highly of? Fat? Carbs? Protein? Perhaps my body needs more of that particular macronutrient and I should be eating more foods that are also high in that same macronutrient.
I’d also note if I felt anything out of the ordinary during this time – anything that felt wrong or annoying. I’d listen to my body – if I notice a pattern happening, say I consistently get hungry at a certain time that is before or after my feeding window, then I’d adjust the feeding window accordingly so that my hunger falls within that range.
My mood would also be something I’d pay particular attention to. Should I become highly irritable or depressed, for example, I’d know something is off. If I feel that I am treating my family and friends differently, that my personality has changed for whatever reason, I’d dial back on the fasting or perhaps eat more calories since something is clearly wrong.
And of course, I’d get regular check-ups with a doctor to see if my hormones are going out of wack.
IF should not be a masochistic diet. It is something that should be sustainable for the individual. If you find that nothing you do seems to allow you to successfully adhere to the IF protocols, then stop. It’s not worth jeopardizing your health, nor your sanity.