Researchers studied how ultra-processed foods affect men’s bodies and reproductive health. In a controlled experiment, men who ate more processed foods showed weight gain, changes in cholesterol levels, and reduced sperm movement—even when they ate the same number of calories as men eating whole foods. The study also found that processed foods contain more harmful chemicals that build up in the body. These findings suggest that the type of food matters just as much as how much you eat when it comes to men’s health.

The Quick Take

  • What they studied: Whether eating ultra-processed foods (like packaged snacks, fast food, and processed meals) harms men’s reproductive health and metabolism, separate from just eating too many calories
  • Who participated: The study involved male participants in a controlled nutrition trial where researchers carefully monitored what they ate. Specific participant numbers and detailed demographics were not provided in the abstract.
  • Key finding: Men who ate ultra-processed foods gained more weight and had worse cholesterol ratios compared to men eating whole, unprocessed foods—and this happened regardless of whether they ate the same total calories. Additionally, sperm movement decreased slightly, and hormone levels changed in ways that could affect fertility.
  • What it means for you: If you’re a man concerned about your health or fertility, choosing whole foods over processed options may be beneficial. However, this is one study, and you should discuss any fertility concerns with a doctor. The findings suggest that food quality matters beyond just calorie counting.

The Research Details

This was a carefully controlled nutrition experiment where participants ate two different diets in a crossover design, meaning each person tried both diets at different times. Researchers compared an unprocessed diet (whole foods) to an ultra-processed diet (packaged and fast foods) while measuring various health markers. The study also tested whether eating extra calories made the problems worse. This type of controlled experiment is considered strong evidence because researchers can carefully control what people eat and measure the direct effects.

By controlling exactly what participants ate and measuring multiple health outcomes—including weight, cholesterol, hormones, and sperm quality—researchers could isolate the specific effects of processed foods themselves, rather than just assuming processed foods are bad because people who eat them tend to be less healthy overall. This approach helps prove cause-and-effect rather than just showing correlation.

This study was published in Cell Metabolism, a respected scientific journal. The controlled design is a strength because researchers managed what participants ate. However, the abstract doesn’t specify how many people participated or how long the study lasted, which are important details for evaluating reliability. The findings about sperm quality were described as ’trending toward impairment’ rather than definitive, suggesting the effect was modest.

What the Results Show

Men eating ultra-processed foods showed increased body weight and an unfavorable shift in their cholesterol ratio (higher LDL, lower HDL) compared to eating unprocessed foods. This happened even when researchers controlled the total calories, meaning the type of food—not just the amount—caused these changes. Several hormones involved in metabolism and sperm production changed, including decreased levels of growth/differentiation factor 15 and follicle-stimulating hormone. Sperm total motility (movement) showed a trend toward decrease, suggesting processed foods may slightly harm sperm function. The study also found that ultra-processed foods led to accumulation of certain pollutants in the body, including increased levels of phthalates, which are chemicals used in plastics and food packaging.

The research revealed that changing caloric intake alone (eating more or less) had different effects on health markers than switching between processed and unprocessed foods. This suggests that both the quality of food and the quantity matter, but they affect the body through different mechanisms. The detection of increased phthalates and other pollutants in the blood after eating processed foods indicates that these foods may expose people to more environmental chemicals.

Previous research has shown that ultra-processed foods are linked to weight gain and poor health, but most studies couldn’t prove whether the food itself caused the problems or whether people who eat processed foods simply have other unhealthy habits. This controlled study strengthens the evidence by showing that processed foods directly cause these harmful changes. The findings about reproductive health effects are particularly novel, as fewer studies have examined how diet affects male fertility.

The abstract doesn’t specify the number of participants, study duration, or detailed participant characteristics, making it difficult to fully evaluate the study’s scope. The changes in sperm quality were described as trends rather than statistically significant findings, meaning they were small and might not be reliable. The study measured short-term effects; it’s unclear whether these changes persist long-term or whether they reverse when people return to eating whole foods. Results may not apply equally to all men, as factors like age, genetics, and baseline health weren’t detailed.

The Bottom Line

Men should prioritize whole, unprocessed foods over ultra-processed options when possible (moderate to strong evidence). This includes choosing fresh fruits, vegetables, whole grains, and minimally processed proteins instead of packaged snacks, fast food, and heavily processed meals. Calorie control remains important, but food quality appears to matter independently. If you have fertility concerns, discuss dietary changes with your doctor.

This research is most relevant to men concerned about their metabolic health, cholesterol levels, or fertility. Men with existing heart disease risk factors or those trying to conceive should pay particular attention. The findings may also interest women who are concerned about their partners’ health. However, this is one study, and individual results may vary based on genetics and other lifestyle factors.

Changes in weight and cholesterol can appear within weeks to months of dietary changes. Hormone level changes may occur on a similar timeline. Improvements in sperm quality typically take 2-3 months, as this is the time required for new sperm to develop. Don’t expect overnight results; sustainable dietary changes work best over months and years.

Want to Apply This Research?

  • Track the percentage of meals made from whole, unprocessed ingredients versus ultra-processed foods daily. Set a goal like ‘80% of meals from whole foods’ and monitor progress weekly. This is more practical than calorie counting alone and aligns with the study’s findings.
  • Use the app to plan one meal per day using whole ingredients, gradually increasing to multiple meals. Create a shopping list feature that highlights unprocessed options and filters out ultra-processed alternatives. Set reminders to meal prep on weekends using whole foods.
  • Track weight weekly and energy levels daily. If using a fitness tracker, monitor resting heart rate as an indicator of cardiovascular health. For those concerned about fertility, consider tracking general wellness metrics. Review progress monthly and adjust meal planning based on what whole-food options work best for your lifestyle.

This research suggests associations between ultra-processed food consumption and reproductive and metabolic health outcomes in men. However, this is one study, and individual results may vary based on genetics, age, overall lifestyle, and other health factors. This information is not a substitute for professional medical advice. Men with fertility concerns, existing health conditions, or those taking medications should consult with a healthcare provider before making significant dietary changes. If you’re trying to conceive and have concerns about fertility, speak with a doctor or fertility specialist for personalized guidance.