Over the past 50 years, the number of people with obesity and type 2 diabetes has gone up a lot.
At the same time, sperm quality in men has gone down. One possible reason for both of these problems is the rising popularity of ultra-processed foods.
These are foods that are made with artificial ingredients, additives, and high levels of sugar, salt, and fat. Scientists know these foods are linked to poor health, but they still have questions.
Are the problems caused by the ingredients themselves, the processing methods, or because people tend to eat too much of them?
Now, an international group of scientists has found that ultra-processed foods can harm your health even if you eat the same number of calories as you would with unprocessed foods. Their study also showed that these foods can raise levels of harmful chemicals in the body that affect sperm health. The study was published in the journal Cell Metabolism.
The study looked at 43 healthy men between the ages of 20 and 35. Each man followed two different diets: one with mostly unprocessed foods, and one with mostly ultra-processed foods. They followed each diet for three weeks with a three-month break in between.
The order of the diets was different for each person, and some men were given extra calories to see how that would affect results. Importantly, both diets had the same amount of calories, protein, fat, and carbohydrates. This helped the researchers isolate the effects of food processing alone.
The results were surprising. Men gained about 1 kilogram more body fat while on the ultra-processed diet, even though the calorie count was the same. Their heart health markers also got worse. This shows that it’s not just how much we eat, but what kind of food we eat that matters.
Even more alarming, the ultra-processed diet raised levels of a plastic-related chemical called phthalate cxMINP in the men’s bodies. This chemical can disrupt hormones.
The study found that levels of testosterone and follicle-stimulating hormone—both important for sperm production—went down during the ultra-processed diet. These changes could harm fertility and reproductive health over time.
Jessica Preston, the lead author of the study, said, “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.”
Professor Romain Barrès, the senior author, added, “We were shocked by how many body functions were disrupted by ultra-processed foods, even in healthy young men. The long-term implications are alarming and highlight the need to revise nutritional guidelines to better protect against chronic disease.”
In summary, this study clearly shows that ultra-processed foods are not just empty calories. They can trigger harmful changes in your body—even if you don’t overeat. This includes weight gain, poor heart health, and lower sperm quality.
People should be cautious about including too many ultra-processed foods in their diets. Governments and health organizations may also need to update dietary advice to better reflect these risks.
If you care about gut health, please read studies about a surprising link between gut health and eye disease risk and Gut troubles could signal future Parkinson’s disease.
For more about gut health, please read studies that this stuff in coffee and chocolate may impact gut health and Gut health is linked to anxiety levels.
The study is published in Cell Metabolism.
Copyright © 2025 Knowridge Science Report. All rights reserved.
