Can losing weight improve your fertility?

When you’re thinking of having a baby, you want to be in the best health possible. If you talk to your doctor about trying to get pregnant, they’ll probably ask about your eating habits, prenatal supplements, and even your weight.

Some people are surprised that weight is part of the equation. But being overweight can alter hormones that control menstrual cycles and ovulation, which affects your ability to conceive.

For example, fat cells can produce estrogen, so your body may produce excess estrogen if you’re overweight, which can prevent you from ovulating regularly. And when you don’t ovulate regularly, it can be hard to time conception.

In some cases, being overweight might also be related to polycystic ovarian syndrome (PCOS), which is an imbalance of reproductive hormones. Women with PCOS have a hard time conceiving due to hormonal imbalances that prevent the ovaries from releasing an egg each month. Many women with PCOS also have insulin resistance, which is associated with excess insulin. And since high insulin levels cause the ovaries to make more testosterone and less estrogen, this can halt ovulation.

If you’re overweight—which typically means you have a BMI of 25 or higher—your doctor may suggest losing weight to regulate ovulation and boost fertility. Even if you have PCOS, weight loss can help to improve the condition.

Andrea Falcone, a dietitian and certified fitness professional, suggests aiming for 150 minutes of activity weekly, split up in any way that fits your lifestyle. “A combination of aerobic exercises, muscle conditioning and flexibility is ultimately where you want to get to,” says Falcone. But don’t overdo it. Excessive exercise places more stress on the body and can actually interrupt ovulation, she says.

When it comes to diet, go with a balanced eating plan that includes:

• Vegetables and fruit – 7-8 servings per day
• Calcium rich foods – yogurt, milk or plant-based milk alternatives
• Whole and enriched grains
• Good quality protein – chicken, fish, tofu, legumes, eggs, etc.
• Low mercury, high omega-3 fat fish twice a week (like salmon and rainbow trout)
• Healthy fats from nuts, olive oil, avocado, etc.
• Limited caffeine (300 mg, or one or two coffees per day)
• No alcohol (research is unclear as to how much it takes to harm a developing baby, so it’s best to abstain completely)
• Fewer ultra-processed foods like salty snacks, fast food, candy and pastries
• A prenatal multivitamin with folic acid

No special diets have been linked to increased fertility. What’s more, starting a very restrictive weight loss diet could actually backfire. Daphna Steinberg, a clinical dietitian with the high-risk obstetrics program at Sunnybrook Health Sciences Centre, cautions against low-carb diets because they lack sufficient folic acid, which is found in enriched grain products like bread and pasta. Folic acid protects babies against spina bifida, and a recent study showed that women on low-carb diets are slightly more likely to have babies with this birth defect.

Experts agree that weight loss is certainly not a quick fix. Losing weight is difficult and, in some cases, it can add unnecessary stress to the process of getting pregnant. “Weight loss isn’t the only answer, especially if going on a diet doubles your stress and adds more self-blame,” says Tom Hannam, OB/GYN and director of the Hannam Fertility Centre in Toronto. He explains that, if you’re having trouble conceiving, it’s difficult to know if weight loss will be the thing that helps. Plus, despite best efforts, a BMI in the “healthy range” is not always achievable.

Instead of focusing on weight, set realistic goals such as “eat one more serving of vegetables daily” or “walk 20 minutes per day.” These small steps add to your healthier lifestyle, and may promote weight loss as an added bonus.

The good news? Even without drastic weight loss, lifestyle changes like eating well and exercising can have positive effects on hormone levels. Even losing five percent of body weight can help increase your chances of getting pregnant. And a healthy lifestyle is important for both parents, so get your partner involved too, advises Hannam.

Focus on these healthy habits, and don’t get too hung up on your actual weight. “The number on the scale doesn’t necessarily reflect your level of fitness or overall health,” says Steinberg.

Read more: Fertility fact vs. fiction
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