Intermittent fasting: Women vs Men

In the third part of this series on intermittent fasting, we shall explore whether gender makes a difference on how intermittent fasting can be ideally implemented. Intermittent fasting works by using WHEN you eat to change your metabolic rate rather than WHAT you eat. Studies have shown great effectiveness when used for chronic obesity, heart health and even things like rheumatic conditions!

If you are a beginner player, you might want to read my post on intermittent fasting - the basics. Or, maybe you’re wondering if age makes a difference to intermittent fasting. As a recap, intermittent fasting has great benefits such as improved insulin resistance, better cardiovascular health and even anti-inflammatory implications. 

If you’ve been wondering if being a male or female changes your bodies response to intermittent fasting, look no further. Fasten your seatbelts, get ready for a rollercoaster ride, we have a hectic journey ahead!

Let’s hop to it!

Intermittent fasting for different genders

Men

Males tend to better at counting macros and calories than women, because the hormone fluctuations that affect a woman’s eating patterns do not occur as strongly in males. However, for those who are over counting calories and controlling all their food intake, intermittent fasting is a great alternative.

Intermittent fasting is a safe and effective method for weight loss in males, especially those experiencing obesity or chronic overweight. (Overweightedness? hmm)

The male body tends to respond to fasting by increasing metabolic rates. This goes back to a survival mechanism honed to perfection from the time of the hunter - gatherers. If food was scarce, the males who were largely responsible for hunting (other than in Amazonian culture) needed to go and get food to ensure continuity of the tribe. So a spike in energy and metabolic rate was necessary! 

Intermittent fasting can increase metabolism in males up to 14% which is quite impressive! However, it is important to note that this has only been tested on short term fasting which indicates that getting the fasting time right is crucial to ensure no long term metabolic slowing. 

Something to take into account is that intermittent fasting actually reduces testosterone levels by increasing testosterone utilisation up to 200%. But rest assured! It has no effect on lean muscle mass and muscular strength. Yay! 

The best intermittent fasting schedule for men

16:8 method

Eating for 8 hours and fasting for 16 hours can be really easy to achieve and also convenient to sustain in the long term, especially when the fasting period runs while you sleep. Additionally, it can work really well during work hours. 

Alternate day fasting 

Also known as Eat Stop Eat. Fasting every second day, or using a modified version of this and consuming 500-600 calories on the alternate day can be an effective method to use. 

My recommendation is to match the fasting days with rest days if you have a workout schedule, as this will marry the energy requirements for the day. If you are a highly active person or have high energy requirements, this method may not be suitable for you. Additionally, this method may not be the most sustainable option.

5:2 method

Eating normally 5 days of the week and fasting for 2 days (either complete abstinence or a modified version of consuming 500-600 calories on fasting days) can be a great way to ensure the health benefits come your way. Again, matching your energy requirements to your calorie consumption is pretty key in making this work.

Women

Those of the female persuasion might need to take a more gradual approach in intermittent fasting. The majority of studies done on intermittent fasting involve men, which means that data showing intermittent fasting is an effective method for weight loss and improved health parameters may not necessarily translate across genders.  

Metabolism slows down much faster in women who fast. Again, if you look at human history, this is a survival mechanism. Women’s bodies respond to scarcity by conserving energy to survive a potentially long-term famine, if no food can be sourced. So intermittent fasting over the long term might actually contribute to weight gain and worsened blood glucose control - a finding that is consistent with the long term effects of dieting and restriction. 

Studies show that fasting for any period of time can cause negative reproductive functionality, involving period regularity, lactation, fertility and pregnancy. The theory is that because women require more energy for reproductive functions of the body, restricting calories in any way will affect them. However, this isn’t conclusive, so I would suggest talking to your doctor before shunning intermittent fasting if you are concerned. 

On the flip side of this, women experiencing hyperandrogenic syndromes such as polycystic ovarian syndrome (PCOS) may benefit from following a fasting schedule, although research is still in the early stages. For PCOS patients, following an early time restricted plan (where the majority of food is consumed before 4pm) might  be more beneficial, as eating later in the day has been connected to increased estrogen production. 

Dr Mindy Pelz, a chiropractic doctor with a bachelors in science, suggests in her book, Fast like a girl that the time of the month affects the effects of fasting. Her suggestion is to avoid intense fasting the week before a period, as glucose is needed for progesterone production. She also states that during times of low estrogen, fast as much as you like. (be reasonable though, you still need to eat!)

The other major concern is the effect of intermittent fasting on bone health. There have been observational studies* showing a compromised effect on bone density in people practicing intermittent fasting. However, interventional studies on time-restricted eating have proven that intermittent fasting up to 6 months at a time may actually improve bone health due to modest weight loss! 

Interestingly, a study in the rehabilitation journal demonstrated that people who combine a high protein diet with calorie restriction experience less bone loss than just restricting calories alone, so if females want to participate in intermittent fasting, increasing protein might protect against bone related implications.

Because there are so many factors to take into consideration, it is important for women to talk to their health care professionals when considering participating in an intermittent fasting plan.

The best intermittent fasting schedules for women

Intermittent fasting for women is slightly different than for men because it is important that women don’t skip meals. Eating consistently and consuming nutritionally rich foods prevents the metabolic slow down! For that reason, some of the most appropriate fasting schedules are listed below. 

Crescendo method

This method involves fasting 12-16 hours two to three days a week. It is crucial to space out the fasting days evenly throughout the week, and not fast on consecutive days.

14:10 method

Eating for 10 hours during the day and fasting for 14 hours. Sleeping during the fasting period makes this method much more sustainable. As stated above, for women with PCOS, starting the eating phase earlier in the day can be really beneficial for weight loss and hormone regulation.

5:2 method

Eating normally for 5 days of the week and fasting for 2 days. For women, it’s recommended to consume 500-600 calories to not trigger the metabolic slow down. This can be a great method but only if if fits into your lifestyle. If you have a highly active lifestyle, work in a job that is physically demanding or have kids (because that definitely is a high energy activity!) , then you may want to choose a different method. 

Conclusion

Whatever method you choose, remember that any dietary change should be as sustainable as possible. Women should focus on gradually building up to the intermittent fasting schedule that works for you, and try to avoid doing anything too intense to ensure your metabolism doesn't suffer. Men, go for a method that works with your work, lifestyle and social calendar.

As always, I'd love to hear your experiences, so comment below with what your intermittent fasting journey has taught you! Has one style worked better than another for you?