Time-restricted eating (TRE) is having a moment in the sun, to say the least. The eating method—which involves consuming all your daily calories within a set number of hours—can help manage weight, but it may impact another unexpected aspect of your health: your fertility.
New research has shown that TRE, a form of intermittent fasting (IF), may improve fertility for those with polycystic ovary syndrome (PCOS). A 2025 review in Metabolism Open examined three studies to determine the relationship between IF, fertility, and PCOS and found that IF helped those with PCOS achieve more predictable ovulation schedules, which can increase the likelihood of pregnancy.
Plus, since fasting can help with weight loss, it can potentially improve fertility for those who are obese and may have hypertension and high cholesterol, which can negatively affect fertility, says Joshua Hurwitz, MD, an OB-GYN and reproductive endocrinologist at Illume Fertility in Connecticut.
However, fasting can also lead to nutritional deficiencies, which may disrupt one’s hormonal balance and decrease egg quality, according to a 2024 study in Cureus Journal of Medical Science that looked at the association between nutritional deficiencies and subfertility. “Human health should be optimal going into pregnancy, and that can be hard to achieve when you are in a caloric deficit,” says Brittany Brown, RD, the founder of Feeding Babies, Nourishing Souls in Nova Scotia, Canada.
So, what’s the real correlation between fasting and fertility? Experts weigh in on TRE and how it can affect your chances of conceiving.
Meet the experts: Joshua Hurwitz, MD, is a board-certified OB-GYN and reproductive endocrinologist and partner at Illume Fertility in Connecticut. Brittany Brown, RD, is the founder of Feeding Babies, Nourishing Souls in Nova Scotia, Canada. Suzanna Chatterjee, MD, is an OB-GYN based in Russellville, Arkansas. Eve Feinberg, MD, is a reproductive endocrinology and infertility specialist at Northwestern Medicine. Mel Spinella, RD, is a New York-based dietitian specializing in fertility and pregnancy nutrition and the founder of Well by Mel Nutrition.
When Fasting Might Help Improve Fertility—And When It Could Hurt
TRE may improve the quality of ovarian cells.
A 2023 study in Free Radical Biology and Medicine looked at older mice to see how intermittent fasting impacts reproduction, and found that one month of fasting every other day improved the quality of developing eggs. The fasting lowered the amount of free radicals, molecules that can interfere with cellular processes, including cell division and reproduction, says Brown.
Still, Brown points out that this study was done in mice, and there’s not enough evidence yet to claim that fasting could have the same effect on humans. “Future research will hopefully uncover how this works, but for now, we need more data before making recommendations,” she says.
It could improve fertility for those with PCOS.
A 2021 study in the Journal of Translational Medicine looked at 15 women between the ages of 18 and 31 who didn’t ovulate. They participated in time-restricted feeding for five weeks, and afterward, 11 of the 15 participants experienced improved menstrual regularity.
Many people with PCOS produce high levels of insulin, which can lead to excess male hormones in the body (such as testosterone), preventing ovulation, Suzanna Chatterjee, MD, an OB-GYN based in Russellville, Arkansas explains. Eating stimulates insulin, so with fewer meal times, those with PCOS could experience fewer spikes of insulin, which could help manage those excess hormones.
TRE may help restore ovulation and improve fertility outcomes without the need for medication for those with PCOS, adds Eve Feinberg, MD, a reproductive endocrinology and infertility specialist at Northwestern Medicine. Still, fasting won’t help everyone with PCOS—in the aforementioned study, four of the 15 women with the condition didn’t experience better menstrual regularity.
So, more research is needed on the connection between PCOS and fasting.
Fasting can help with weight loss, which in turn may improve fertility for people with obesity.
Those with obesity are predisposed to have conditions such as hypertension, high cholesterol, and diabetes, which can “impair natural fertility, as well as lower the success rates of fertility treatment,” says Dr. Hurwitz. “Even a modest weight loss of 5 to 10 percent can improve ovulation and hormone balance.”
Still, weight loss is only one piece of the puzzle. “Not everyone who is overweight will have trouble conceiving,” and vice versa, he adds.
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Plus, studies on TRE’s effectiveness as a weight loss tool are conflicting. A 2021 study in Nutrition & Diabetes, which followed 78 men and women with obesity, found subjects had “meaningful weight loss” after following a TRE plan for eight weeks. But a 2023 study of 547 adults over six months in the Journal of the American Heart Association found that TRE did not help subjects lose weight. So, more research is needed.
Who Should Try TRE For The Fertility Impact
Experts say those with PCOS and those who are obese may benefit from TRE. But for the general population, there are other better ways to improve one’s fertility, such as exercising and eating healthy, balanced meals. “Eating enough, especially nutrient-dense foods throughout the day, is essential for a healthy menstrual cycle,” as well as ovulation, says Mel Spinella, RD, a New York-based dietitian specializing in fertility and pregnancy nutrition and the founder of Well by Mel Nutrition.
Brown also advocates for a more natural, eat-when-you’re-hungry approach to mealtimes for those who are actively trying to conceive—even for those with PCOS—and particularly once pregnancy is possible or confirmed. “Reliable and consistent energy intake is essential for reproductive health, especially in the early moments of pregnancy,” she says. She says that her female clients generally find more success conceiving when they follow less restrictive diets that focus on consuming healthy foods.
Plus, the research on fasting and fertility is still in the early phases. “Ultimately, there is a need for large-scale, long-term randomized control trials to truly understand the long-term impacts of TRE on fertility,” Spinella says.
The Most Effective Fasting Schedules For Fertility
When it comes to intermittent fasting, there are a ton of different schedules breaking down when to eat, from the more flexible 14:10 (14 hours of fasting and 10 hours of eating), to the more restrictive 20:4 plan (20 hours of fasting and four hours of eating).
Brown says intense schedules like 20:4 can make it difficult to meet daily nutrient needs, which are essential before getting pregnant. Meanwhile, a 12:12 approach is more flexible and easier to follow for success. For instance, eating only between 7 a.m. and 7 p.m. might naturally reduce late-night snacking on ultra-processed foods without being overly rigid. However, Dr. Chatterjee recommends following a 16:8 schedule, particularly for women with PCOS who are hoping to regulate their cycle.
Before beginning any fasting schedule, it’s always recommended that you check in with your medical provider to see what they think, Dr. Hurwitz says. At the end of the day, everyone is different and “there’s no one-size-fits-all answer,” to how your body will feel during your fertility journey, Brown says. The way you eat is totally up to you and what will make your body feel best.
Jillian Pretzel is a California-based writer who specializes in wellness, nutrition, and parenting. Her work has appeared in The New York Times, The Washington Post, Parents Magazine, CNN, NBC, Today, Good Housekeeping, and more. She has a master’s degree from Chapman University. In her free time, Jillian can either be found testing various dessert recipes or chasing her kids around local playgrounds.
