If it’s done properly, intermittent fasting (IF) works well for men and women.
But women are more sensitive than men to calorie restriction – so intermittent fasting for females should be more moderate.
Some studies indicate no real difference between how men and women react to IF, while others show that overly strict fasting regimes can trigger hormonal disruptions, insulin resistance and infertility in women.
Let’s look at the evidence.
One study that received a lot of attention looked at eight men and eight women undertaking alternate day fasting.
The men’s insulin sensitivity improved, but the women’s worsened.
However, this diet allowed no food on the fasting day.
The fast went for almost a day and a half – from dinner one evening to breakfast two mornings later.
I don’t recommend such a harsh fast for women.
I prefer an alternate day modified fast, which allows 500-600 calories on the fasting day.
Other studies have found IF causes health problems in rats.
But rats are foragers that evolved to eat in many small bursts throughout the day.
Humans evolved as hunter-gatherers.
Before the invention of agriculture, our ancestors had to eat intermittently, so IF is in line with our evolutionary heritage.
Let’s look at some better research.
The 5:2 diet
A University of South Australia study divided 137 adults (77 women and 60 men) with type 2 diabetes into two groups – 70 on the 5:2 diet and 67 on a continuous calorie restriction diet.
There were no bad health effects for the fasters.
Alternate day fasting
A 2016 review of 28 studies found that ADF is easier to comply with than a standard daily calorie restriction diet, plus it delivers greater fat loss and preserves more muscle mass.
In June 2018, the University of Illinois at Chicago researchers released a study that showed daily fasting improved weight, blood pressure and fasting insulin levels in 23 obese volunteers, including 20 women.
How to get ready for fasting
Upgrade your diet.
Cut back on processed foods, sugars and starches.
Eat more protein and fiber, plus some good fats and oils.
This will boost your weight loss and health and reduce food cravings during fasting.
If you snack after dinner, stop.
Not eating between dinner and breakfast gives you an 11 to 13-hour fast – a big head start.
Easing into a 5:2 fasting schedule
There’s no point doing alternate day fasting until you have succeeded in sticking with 5:2.
You can upgrade to an alternate day modified fast later (either every second day or Monday, Wednesday and Friday), but the 5:2 system might be all you need.
Start with 1000 calories on each fasting day and cut back until you’re down to 500-600 calories.
On fasting days:
- Wait until you feel hungry before eating your first meal – this will be hard at first, but it helps curb hunger.
- Eat to feel full and curb cravings – consume plenty of protein and fiber and keep carbs very low.
Easing into a daily fasting schedule
The daily fast might be the easiest system to follow.
A veteran intermittent fasting researcher said fewer participants dropped out of her recent daily fasting study compared to her many studies on alternate day modified fasting.
But don’t go straight to the 16:8 diet.
A 16-hour fast is too much to start with.
Start with 12 or 13 hours and build up from there.
Eat breakfast a little later each day and you’ll soon be at a 14:10 fasting/eating ratio.
Stick with that for a couple of weeks before deciding whether you need a shorter eating window.
Many women get very good results with 14:10 or 15:9.
A typical 14:10 day might be breakfast at 8.30 am and dinner at 6.30 pm.
A typical 16:8 day might be brunch at 10.30 am and dinner at 6.30 pm.
Be strict on weekdays.
But consider having a social breakfast once a week with friends or family if you think that might help your long-term compliance.
Take the fast track
Many studies show sensible intermittent fasting results in improved health.
Intermittent fasting benefits for women include weight loss and reductions in health risks, such as insulin and blood pressure levels.
Thousands of women – including many of my clients – have used IF to transform their bodies, health and lives.
Now it’s your turn.