Trying to conceive comes with an overwhelming amount of advice. Eat this, avoid that, manage your stress, sleep more, exercise but not too much. The guidance accumulates quickly and what starts as an effort to be healthier can easily slide into anxiety about every single food choice.
But a recent study is cutting through some of that noise with a finding that is both striking and practical. Research from McMaster University suggests that the degree to which food is processed, not its calorie count and not its macronutrient breakdown, may have a measurable impact on a woman’s ability to conceive. And the foods in question are not the obvious offenders. They include the protein bars, flavored yogurts and gluten-free snacks that line the supposedly healthy sections of most grocery stores.
The study behind the finding
Researchers analyzed dietary data from more than 2,500 women between the ages of 20 and 45 who participated in a large national health and nutrition survey. The dataset was comprehensive, drawing on detailed dietary recalls, in-depth health interviews and lab testing to build a thorough picture of each participant’s eating habits and overall health status.
The research team looked at two primary factors: how much of each woman’s daily diet came from ultra-processed foods and how closely her eating patterns aligned with a Mediterranean-style diet heavy in whole foods. They then compared those patterns against self-reported fertility status, defining infertility as trying to conceive for at least a year without success.
Women who reported fertility challenges consumed a notably higher share of ultra-processed foods, roughly 31 percent of their daily intake, compared to those who did not report similar difficulties. They also scored lower on overall diet quality. Even after researchers accounted for age, body weight, socioeconomic status and other relevant health variables, higher ultra-processed food consumption was still associated with approximately 60 percent lower odds of fertility.
This was an observational study, which means it cannot establish direct cause and effect. But the consistency and strength of the association are difficult to dismiss, particularly given how prevalent these foods are in everyday diets.
What might explain the connection
Researchers point to several possible mechanisms. Ultra-processed foods frequently contain additives, preservatives and compounds introduced through industrial processing or packaging materials that have been associated with hormone disruption in prior research. Substances like BPA and phthalates, which can leach from certain types of food packaging, have shown up repeatedly in studies examining reproductive health outcomes.
There is also the broader issue of nutritional displacement. A diet dominated by ultra-processed foods tends to crowd out the whole foods that support hormone balance and metabolic health, including vegetables, fruits, legumes and healthy fats. That displacement matters because the reproductive system is sensitive to nutritional deficiencies and imbalances that may not register as obvious symptoms until conception becomes difficult.
Chronic low-grade inflammation is another factor researchers have flagged. Highly processed diets have consistently been associated with elevated inflammatory markers, and inflammation can interfere with ovulation, hormone signaling and implantation. The combination of those pathways gives researchers reason to believe the relationship between ultra-processed food consumption and fertility is more than coincidental.
Shifting your diet without overhauling your life
None of this is meant to generate guilt or panic. Fertility is shaped by many factors, most of them beyond anyone’s direct control. Diet is one variable among many, and no single food choice in either direction is going to be decisive.
What the research offers is a useful framework for thinking about patterns rather than individual foods. The goal is not to achieve a perfect diet but to gradually shift the overall balance toward foods that are less processed and more whole. Swapping a protein bar for fruit with nut butter, choosing plain yogurt over a heavily flavored version, reading ingredient labels and gravitating toward the shorter and simpler ones, and adding more vegetables and whole grains to meals that already exist in your routine are all low-pressure starting points.
Adding more whole foods over time naturally reduces the space that ultra-processed options occupy in a diet. That directional shift, repeated consistently across weeks and months, is what the research suggests actually matters.
