A balanced fat-to-muscle ratio can improve your chances of conception and support a healthy pregnancy.
Are you thinking about getting pregnant now or sometime in the future? Or maybe you’ve been trying and haven't gotten a positive test yet. If expanding your family is on your mind, listen up. There are many things that affect fertility in both men and women. This can include everything from your age to your stress load, environmental toxin exposure, diet and medication use. But one factor that isn’t as widely discussed is your body composition.
Body composition, which refers to the ratio of fat, muscle, and bone in your body, plays a crucial role in fertility. This important health marker has an effect on everything from hormonal balance to sperm quantity and menstrual health and maintaining a healthy fat-to-muscle ratio is essential for optimal reproductive function. If your body composition is too high or too low, it can disrupt this delicate balance, making conception more challenging.
Understanding how body composition impacts fertility can empower you to take proactive steps toward optimizing your reproductive potential.
Related: What You Get in Your Prenuvo Body Composition Analysis Report
Excessive Body Fat in Women
Excess fat can disrupt hormone balance in multiple ways. “It increases estrogen production, which can disrupt the normal feedback loop that regulates ovulation,” explains Shannon Lotus Ashley, MD, Senior Preventive Medicine Physician at Prenuvo. “And increased leptin levels (a hormone from fat tissue) can lead to irregular or absent ovulation.” Having too much fat, particularly in the belly region, can make the body less responsive to insulin, which can lead to hormone imbalances. “This is a key factor in Polycystic Ovary Syndrome (PCOS), a common condition that can impact your menstrual cycle and make it harder to get pregnant,” adds Dr. Ashley.
The traditional way experts quantify body fat is by looking at a person’s body mass index. This is calculated as their body weight in kilograms divided by the square of their height in meters. A BMI of 18.5 to 25 is considered to be a healthy weight, while 25 to 30 is overweight and 30 and above is obese.
Note: While BMI is good for a baseline, it has its limitations and doesn’t provide a full picture of a person’s health. For example, visceral fat—hidden behind the abdominal wall—can’t be measured directly without advanced imaging. Preunvo’s whole body scan with body composition analysis, on the other hand, offers a comprehensive breakdown of your physical makeup, including fat mass, lean muscle mass, body symmetry, and the size of your abdominal organs, giving you deeper insight into what’s happening inside your body.
Related: Why Tracking Your BMI Is Becoming Irrelevant
Research shows that women who are obese are around three times more likely to experience infertility compared to those with a normal BMI. This is due to factors such as increased insulin resistance and androgen production (male hormones like testosterone that are also present in females), which are known to disrupt ovulation. One Dutch study found that women with more belly fat (measured by waist-to-hip ratio) had a harder time getting pregnant. For every small increase in this ratio, their chances of conceiving dropped by 30%.
“Obesity is associated with anovulation (failure to ovulate) due to its effects on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion,” adds Dr. Ashley. And even in women with regular cycles, she says, obesity reduces egg quality and uterine readiness, lowering pregnancy success rates. Excess fat that contributes to chronic inflammation, may also worsen conditions like endometriosis that can negatively affect fertility.
And conceiving while obese can increase a risk of miscarriage as higher fat levels are linked to increased inflammation and oxidative stress, affecting embryo implantation and placental development. More body fat also increases the risk of gestational diabetes and preeclampsia, both of which raise the risks of pregnancy loss if not properly managed.
Excessive Body Fat in Males
High body fat and obesity also negatively impact fertility in men. This can especially be the case when it comes to sperm quality. Research shows that males with a BMI over 30 have a significantly higher risk of reduced sperm concentration and total sperm count. In fact, obese men may exhibit a 20-50% decrease in sperm quality compared to men with a normal BMI.
“Fat tissue converts testosterone into estrogen, which can lower free testosterone and disrupt sperm production, leading to low libido, erectile dysfunction (ED), and reduced sperm quality.” And increased estrogen has been shown to further this cycle by suppressing testosterone levels.
“Higher body fat can cause higher DNA fragmentation in sperm due to oxidative stress and inflammation,” adds Dr. Ashley. It can also contribute to reduced sperm motility (movement) and morphology (shape) and lead to an increased risk of male-factor infertility.
And when it comes to getting busy, high fat content can be a mood killer. “Obesity contributes to vascular dysfunction, insulin resistance, and hormonal imbalances, all of which impair sexual function,” says Dr. Ashley. “It also increases one’s risk of metabolic syndrome, which further worsens sperm health and testosterone levels.”
Too Little Body Fat in Women
In women with a low BMI, below 18.5, insufficient fat reserves reduce estrogen production, which is critical for follicle development and menstrual regularity. “Women with less than 18-20% body fat often experience hypothalamic amenorrhea (a lack of menstruation) due to suppressed gonadotropin-releasing hormone (GnRH) secretion, leading to low estrogen, FSH/LH levels, and ovulatory dysfunction,” says Dr. Ashley. This, she explains, is common in elite athletes, dancers, and those with eating disorders.
Too little body fat can also lead to low estrogen, which is essential for follicular development and endometrial thickening. “And too thin of a uterine lining can lead to poor implantation of an embryo,” says Dr. Ashley. She notes that low body weight can also reduce egg quality, which can lead to a higher risk of early pregnancy loss and poor response to fertility treatments.
Too Little Body Fat in Men
In men, extremely low body fat can also be problematic. “Very low body fat levels can reduce testosterone production, negatively impacting sperm production and libido,” says Dr. Ashley. This, she says, is often seen in endurance athletes, like marathon runners, cyclists, or men who follow low-fat diets. A study of 3,966 sperm donors, for instance, found that males underweight (BMI < 18.5) had reduced sperm concentration, total sperm number, and total motile sperm count.
The Role of Muscle Mass
Muscle mass also plays a significant role in supporting fertility. In women, adequate muscle helps to maintain balanced hormones by supporting metabolic health and insulin sensitivity. Polycystic ovary syndrome (PCOS), which affects around 5-10% of reproductive-age women, is often linked to obesity. As a result, insulin resistance can lead to excess androgen production and ovulation issues. Research shows that building lean muscle through strength training can improve insulin sensitivity, potentially mitigating these effects.
Muscle mass is closely linked to testosterone levels in men, which are crucial for sperm production. Higher muscle mass is associated with better testosterone levels, while low muscle mass, often seen in those with obesity, can lead to reduced sperm quality. A Harvard study found that men who frequently lifted or moved heavy objects at work had a 46% higher sperm concentration and a 44% higher total sperm count compared to those with less physical jobs.
Ready to optimize your body composition levels for fertility? Take these steps.
Gain insights with Prenuvo: A healthy fat-to-muscle ratio is key to supporting reproductive health. It’s recommended that people trying to get pregnant aim for the following:
In order to help hit these targets, it’s important to know where you stand. A Prenuvo Whole Body MRI Enhanced Screen with body composition analysis can help you get a clear understanding of your body’s fat-to-muscle ratio. It can also provide insights to help you make lifestyle changes needed to maintain an ideal body composition to align with your fertility goals. In addition, a whole body scan checks for hundreds of conditions and has the ability to help identify things like ovarian cysts, signs of endometriosis and uterine fibroids, which could also, if untreated, reduce your chances of a successful pregnancy.
Prioritize a Mediterranean Diet: Eat a balanced diet rich in whole foods, healthy fats, and fiber to help you to maintain a healthy body composition. Try not to skip meals and prioritize lean protein, to help support muscle growth and repair. Limit processed foods and sugary foods and drinks. A Mediterranean diet, in particular, has been shown to increase fertility.
Exercise but avoid overdoing it: Engaging in regular physical activity that includes both cardiovascular and strength training exercises can help maintain an optimal balance of fat and muscle. Aim for moderate intensity exercise, as studies have shown that regular vigorous exercise can throw off ovulation and menstrual cycles and negatively affect fertility. Working out too hard can also reduce sperm quality.
Avoid yo-yo dieting or extreme caloric restriction: Instead of embracing fad diets or massive calorie cutting, focus on gradual, sustainable weight management. Rapid or frequent weight changes can also wreak havoc on your fertility by disrupting hormone levels, throwing off menstrual cycles and reduced sperm quality.
Make time to unwind: Chronic stress can lead to weight changes, which can negatively impact fertility. And stress in itself can also reduce one’s chance of conception, especially in women. Prioritize activities that help you to feel calmer and centered, whether that’s meditation, journaling, taking a walk outdoors or getting lost in a good book.
Don’t skimp on sleep: Studies show that lack of sleep can disrupt hormones involved in ovulation and sperm production, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Aim for 7 to 9 hours per night.
Ready to take a closer look at your fat-to-muscle ratio? Book a call with your personal care coordinator to learn more about a Prenuvo Whole Body MRI Enhanced Screen with body composition analysis.
.png)
