Study Links Ultra-Processed Foods to Metabolic and Reproductive Harm

Researchers studied 43 men aged 20 to 35, who spent three weeks on both ultra-processed and minimally processed diets, separated by a three-month washout period. Half of the participants consumed normal calorie amounts, while the other half received an additional 500 calories per day. Both diets were carefully matched for calories, protein, carbohydrates, and fats.

The findings showed that men gained around 1 kg more fat mass on the ultra-processed diet regardless of calorie intake. Additionally, several cardiovascular health markers worsened on the ultra-processed diet. Worryingly, the study also found increased levels of phthalate cxMINP, a hormone-disrupting chemical used in plastics, in men consuming ultra-processed foods. This was linked to decreases in testosterone and follicle-stimulating hormone, essential for sperm production.

“We were shocked by the extent to which ultra-processed foods disrupted body functions, even in healthy young men," said Professor Romain Barrès, senior author of the study. He emphasized the need to reevaluate nutritional guidelines to protect against chronic diseases exacerbated by ultra-processed diets.

This study highlighted that the harm caused by ultra-processed foods goes beyond excess calorie consumption, pointing to the processed nature of these foods as a fundamental risk to metabolic and reproductive health.

Reference: Preston, J. M., et al. (2025). Effect of ultra-processed food consumption on male reproductive and metabolic health. Cell Metabolism. doi.org/10.1016/j.cmet.2025.08.004