What You Eat Is Hurting Your Hormones: New Research Links Ultra-Processed Foods to Lower Testosterone and Sperm Quality in Men

Your testosterone level is impacted by what you eat.

If you're a man living in Shreveport or anywhere in northwest Louisiana and you're concerned about your energy levels, hormones, or fertility, a landmark new study published in the journal Cell Metabolism has something important to say about what's on your plate — and it might surprise you.

The Study That's Changing How Doctors Think About Men's Health and Diet

In October 2025, researchers from the University of Copenhagen published one of the most carefully controlled human nutrition studies ever conducted on men's reproductive and metabolic health. The trial enrolled 43 healthy men between the ages of 20 and 35 and put them on two different diets — one built around whole, minimally processed foods and one built around ultra-processed foods (UPFs). Each diet lasted three weeks, with a three-month break in between so the body could return to baseline. Crucially, both diets were matched for calories, protein, carbohydrates, and fat. The only real difference was how the food was made.

The results, published in Cell Metabolism and covered by The Washington Post, were striking enough that researchers called them "alarming."

What Counts as Ultra-Processed Food?

You may have heard the term ultra-processed food before, but it's worth being specific. Food scientists use a classification system called NOVA, which sorts foods into four groups based on how much industrial processing they've undergone. Ultra-processed foods — NOVA Group 4 — are not simply "junk food." They include a wide range of everyday products: packaged breads, flavored yogurts, breakfast cereals, deli meats, frozen meals, flavored chips, soft drinks, and many fast-food items. What makes them "ultra-processed" is that they contain industrial ingredients — emulsifiers, colorings, flavor enhancers, preservatives — that you would not find in a home kitchen, and they are manufactured using processes like extrusion, pre-frying, and moulding that transform the food at a molecular level.

In the United States, ultra-processed foods account for more than half of daily calorie intake for most adults. In other words, for many of our patients here in Shreveport, the ultra-processed diet in this study is not far from their current diet.

What Happened to the Men Who Ate Ultra-Processed Foods?

Even though both groups ate the same number of calories, the men on the ultra-processed diet gained significantly more body fat — roughly one kilogram (about 2.2 pounds) more fat mass in just three weeks. Their LDL-to-HDL cholesterol ratios worsened, a key marker of cardiovascular risk. And perhaps most importantly for male health, their hormones shifted in the wrong direction.

Men on the ultra-processed diet showed decreased levels of follicle-stimulating hormone (FSH), a hormone produced in the brain that directly drives sperm production. Testosterone levels also trended downward. While the decline in sperm motility (the ability of sperm to swim) did not reach full statistical significance — the researchers noted this may be because three weeks is a short window for sperm parameters to fully reflect dietary change — the direction of the findings was consistent and concerning.

The researchers also found something unexpected: men eating the ultra-processed diet had higher levels of a chemical called cxMINP in their blood. This is a metabolite of phthalates, a class of industrial plasticizers used in food packaging and food processing equipment. Phthalates are well-established endocrine disruptors — meaning they interfere with the body's hormone signaling system. The fact that they showed up at higher levels in men eating ultra-processed foods, independent of calorie intake, suggests that the packaging and processing itself is a source of hormonal exposure that goes far beyond nutrition.

It Is Not Just About Eating Too Much

One of the most important takeaways from this study is that the harm from ultra-processed foods cannot be explained by overeating alone. Even when calorie intake was carefully controlled, the men eating ultra-processed foods gained more fat, had worse cholesterol numbers, and experienced hormonal disruption compared to the men eating whole foods. As the lead author, Dr. Jessica Preston, put it: "Our results prove that ultra-processed foods harm our reproductive and metabolic health, even if they're not eaten in excess. This indicates that it is the processed nature of these foods that makes them harmful."

This is a significant shift from the conventional wisdom that weight and metabolic health are simply a matter of "calories in, calories out." The source and quality of those calories — and the chemical environment they carry with them — matter too.

If you have been told your testosterone is low, your cholesterol is creeping up, or your weight is hard to manage despite trying to eat in moderation, this research is directly relevant to your situation. At Shreveport Direct Care, we take a personalized, root-cause approach to men's health, and conversations like this one — about diet, hormones, and long-term metabolic risk — are exactly the kind of care we provide. We encourage you to visit us at shreveportdirectcare.com to learn more about how we work with patients on issues like low testosterone, metabolic health, and preventive wellness.

Why This Matters for Men in Shreveport and Louisiana

Louisiana consistently ranks among the states with the highest rates of obesity, diabetes, and cardiovascular disease. Diet is a central driver of all three. This study adds another layer of urgency to those conversations: the foods that are most heavily marketed and most affordable in our food environment are the same foods now being linked — in a rigorous, controlled human trial — to hormonal disruption, fat gain, and declining sperm quality in men as young as 20.

Male fertility has also been declining globally for decades. Sperm counts have dropped by roughly 60 percent since the 1970s. Endocrine-disrupting chemicals, poor diet quality, and rising rates of obesity are all considered contributing factors. This study suggests that ultra-processed foods may be pulling several of those levers at once: delivering poor nutrients, promoting fat gain, suppressing reproductive hormones, and introducing hormone-disrupting phthalates from packaging — all at the same time.

What You Can Do Starting Now

The good news is that dietary change is one of the most powerful tools available for improving hormonal and metabolic health, and the benefits can appear quickly. This study showed measurable hormonal changes in just three weeks. Here are some practical starting points:

Replace at least one ultra-processed food per day with a minimally processed alternative. Swap flavored chips for a handful of nuts. Replace a packaged breakfast item with eggs or fresh fruit. Choose water or sparkling water over sodas or flavored drinks. Cook more meals from whole ingredients — fresh meat, vegetables, legumes, and whole grains — and reduce your reliance on packaged or fast food. These are not all-or-nothing changes. Even partial reductions in ultra-processed food consumption are likely to be beneficial.

If you are concerned about low testosterone, fertility, weight management, or cardiovascular risk, working with a primary care physician who takes time to understand your diet, lifestyle, and lab values is the most effective path forward. At Shreveport Direct Care, we offer direct primary care memberships that give patients unhurried appointments and access to personalized care focused on prevention and long-term health. You can learn more and schedule a visit at shreveportdirectcare.com.

Sources

Preston JM, Iversen J, Hufnagel A, et al. Effect of ultra-processed food consumption on male reproductive and metabolic health. Cell Metab. 2025;37(10):1950-1960.e2. doi:10.1016/j.cmet.2025.08.004

O'Connor A. Ultra-processed diet decreases male sex hormones, new study suggests. The Washington Post. August 28, 2025. https://www.washingtonpost.com/wellness/2025/08/28/ultra-processed-sperm-quality-male-fertility/