Are you a frustrated female who has tried everything to lose weight but can’t seem to get the scale to budge? If so, you’re not alone. And if there’s a male friend, family member, or significant other in your life who seems to drop pounds with ease, it can be quite disheartening.

Unfortunately, nature can be unequal sometimes, and there are sex-based differences in how men and women tend to lose or gain weight — many of which aren’t always reflected in the research on intermittent fasting. 

So, if your male personal trainer, brother, husband, or any other guy in your life is raving about intermittent fasting, and you’re wondering, “How does this apply to me?” keep reading!

Ready to jumpstart your intermittent fasting journey? Try the Simple quiz and get access to our intelligent fasting tracker. It’ll guide you daily, providing tips on when to eat and fast, adapting to your unique lifestyle. Discover more features tailored just for you!

Which sex differences make a difference?

It can be tricky sometimes to know which health factors are true for all humans and which factors may differ by individuals. 

In the case of sex differences — i.e., physiological differences — there are indeed average differences between male and female bodies, such as the hormonal environment that men and women are likely to have.[1] 

But, women will also have different experiences across their lifespans — for instance, a 25-year-old woman will have a different hormonal environment than, say, a 35-year-old woman who is pregnant or a 65-year-old woman who has passed through menopause.

Differences in body fat, weight gain, and metabolism

In general, here’s what we know to be true — again, if we’re looking at broad, average differences between big groups. 

• Women tend to have less lean mass than men and more body fat.[2] 
• Women’s bodies are also more predisposed to storing body fat, thanks to the role of body fat in reproduction.[3] 
• Their bodies also react more strongly to an energy deficit (in other words, dieting), and may defend body fat — for instance, by making women hungrier.[4]
• Along with less lean mass, women, on average, have smaller bodies.
• Collectively, this means that women have a lower metabolic rate than men — in other words, they’ll burn fewer calories more slowly. And their hormonal environments lean towards storing fat rather than losing it.[5]

Then, there are other factors in the mix. Both men’s and women’s metabolisms are affected by stress, lack of sleep, and calorie-restrictive diets.[6,7] But evidence shows that if you’re female, you’ll gain more weight than males do in these scenarios.

Stress

According to the American Psychological Association (APA), women are more likely than men to say they have “a great deal of stress.”[8] 

And women are more likely to say they eat in response to stress (31% vs. 21%) and are less likely to exercise (24% vs. 35%). 

Other research supports the APA’s findings and agrees that females are more likely than males to gain weight as a response to stress.[9,10,11]

Sleep

The same APA survey found that only 1/3 of women say they get enough sleep, even though they’re trying.[8] This is unsurprising, as women’s sleep is often disrupted by many things like hormonal changes during the menopause transition, having young children, or a (usually male) partner who snores.[12,13]

Research suggests that sleep loss affects women more than men. Women who don’t get enough sleep tend to be more overweight and have an increased risk for type 2 diabetes and heart disease.[14,15]

Dieting

Thanks to societal pressure, women are more likely to try restricting food to lose weight and feel frustrated about their own nutritional behaviors.[16,17] This can set up a cycle of alternating restriction and weight gain for some women.[18]

Household dynamics

Finally, despite social changes, women still tend to do more meal planning and food prep for families.[19,20] 

This can also affect which intermittent fasting routine they choose — for instance, they might want to share family dinners rather than being the one who isn’t eating, or they might welcome the convenience of not having to prepare one more meal.

And if you’ve ever found meal planning a tad overwhelming (especially when incorporating a new eating routine), Simple has the answer! Explore our collection of recipes and simplify your meal prep journey! From hearty breakfasts to nutritious dinners, we have something to suit every palate. Whet your appetite and take our quiz to discover our tasty offerings! 

Intermittent fasting, weight loss, and hormonal health

Why might these sex differences occur? One factor in the mix is the role of body fat in ensuring healthy fertility and hormonal function.

Menstruation

Between puberty and menopause, women need a certain percentage of body fat to maintain normal menses and fertility.[3] This lets the body know a potential pregnancy is safe, and this hormonal mechanism will operate whether women actually plan to become pregnant or not.

Pregnancy and postpartum

If you’re pregnant or have recently given birth and are now breastfeeding, now’s not the time to fast or try to lose weight. 

Women’s energy needs go up by around 300–500 calories (kcal) per day during the second and third trimesters of pregnancy.[21] Breastfeeding has a similar demand of around 330 to 400 calories per day.[22]

Perimenopause and menopause

For most women, the perimenopausal transition before menopause begins to unfold somewhere in their 40s. 

They produce less estrogen and progesterone, which begins to change where they put on body fat. Women may notice more fat around their middle as a result. Declining hormones also affect women’s sleep, mood, energy levels, and appetite — all of which promote weight gain and having more body fat.[23]

Officially, menopause is 12 months after the last menstrual period. On average, this is sometime around the early 50s for most women. 

Postmenopause

After menopause, hormones may continue to fluctuate for several more years. Women may continue to notice weight gain and their body shape changing.

What does this mean for fasting and weight loss for women?

In general, time-restricted eating forms of intermittent fasting are safe for healthy adult women who are not pregnant, breastfeeding, or trying to get pregnant.

The most common benefits of intermittent fasting for women are: 

• Weight loss: Intermittent fasting is effective for weight loss in both men and women.[24] 
• Less belly fat: Intermittent fasting reduces body fat and effectively reduces abdominal fat, which many women find increases with age.[25] 
• Metabolic health: Several studies have found that women who were overweight or living with obesity improved their blood sugar control and blood lipids (a potential risk factor for heart disease) after following an intermittent fasting routine.[26]

However, it may be important for women to choose less stringent schedules, such as shorter fasts, including 14:10 (fast for 14 hours and eat within a 10-hour window) or 12:12 (fast for 12 hours and eat within a 12-hour window).

A special case: PCOS

Evidence suggests that women with polycystic ovary syndrome (PCOS) could potentially benefit from intermittent fasting.[27,28] For more, see our article on PCOS and intermittent fasting here. 

Important: This isn’t medical advice, and we still need more research to be sure. If you have PCOS or any other health concern, please consult with your healthcare provider before making any major nutrition or lifestyle changes!

What’s a good intermittent fasting routine for women? 

No matter who you are, start gradually if you’re new to intermittent fasting. 

(And remember to consult with your healthcare provider before any major nutrition and lifestyle changes!) 

Stay aware of any changes you notice in your body, such as changes in your energy levels, sleep, appetite, or menstrual cycle (if you normally have one).

Begin with 12:12

Start with a 12:12 routine, which means fasting for 12 hours (typically overnight) plus a 12-hour eating window. This may be enough to see your desired results, especially if you combine it with wise, nutritious food choices. 

However, if you still feel comfortable and all signs point to health, you can move to a 14:10 fast, which involves 14 hours of fasting plus a 10-hour eating window. 

Menopause and after: Explore 16:8 — if you like

If you are in your 50s and 60s and are focused on weight loss as well as improving health, you may find that a longer fast, such as 16:8, works better for you. We also don’t recommend fasting for anyone over the age of 80.