Are Snacks Targeting Sperm Too? The Trap of "Same Calories" — How Ultra-Processed Foods Shake Up Body Fat and Hormones

Introduction: The Mystery of "Same Calories, Different Effects"

"The nutritional content is the same, yet the weight gain differs." This discrepancy has been directly addressed by the latest clinical trials. The WIRED article published on September 9, 2025, details research that shows how Ultra-Processed Foods (UPF) can have health impacts that are difficult to explain through calorie counting alone, as demonstrated by various metabolic, endocrine, and reproductive indicators. The study involved 43 healthy men aged 20-35. It was a controlled feeding trial with a 2×2 crossover design, where participants consumed unprocessed foods and UPFs for three weeks each. Both diets were matched for total energy and macronutrient ratios, with some participants also subjected to a **+500kcal high-calorie condition. Despite this, during the UPF period, body fat increased by an average of about 1kg, and there were observed increases in blood LDL and blood pressure. Additionally, decreases in testosterone and FSH and increases in plastic-derived phthalates cxMINP** were observed. The research team concludes that the degree of processing itself alters the body's response.WIRED.jpCell

Why "Degree of Processing" Matters: The NOVA Classification

When discussing UPFs, the NOVA classification inevitably comes up. Proposed by the Public Health Research Center at the University of São Paulo, Brazil, this classification divides foods into four groups based on the purpose and degree of processing: (1) unprocessed or minimally processed, (2) culinary ingredients, (3) processed foods, and (4) ultra-processed foods. UPFs are characterized by industrial formulations (such as refined sugars, oils, starches, protein isolates) and additives, optimized for habitual consumption and ready availability.fsp.usp.br

On the other hand, the NOVA definition has been criticized as "vague and arbitrary." It does not adequately reflect nutritional composition, and the health impacts of the same "UPF" can vary. Recent articles and reviews highlight both calls for refining the definition and the urgency of policy implementation.NaturePMC

Mapping the Evidence: The Intersection of Observational and Interventional Studies

Before simply condemning "UPF = bad," it's important to take a broader view. An umbrella review of observational studies reported consistent associations between high UPF intake and cardiovascular disease, diabetes, mental disorders, and mortality across 32 outcomes (though many had low to moderate quality ratings).BMJBMJ Group

On the intervention front, the 2019 NIH inpatient-controlled crossover trial is emblematic. When provided with diets differing only in processing level, the UPF group consumed about 500kcal more per day, leading to significant short-term weight gain. This suggests that taste, texture, and ease of consumption (reduced friction in eating behavior) may promote overconsumption.CellNIH Record

The recent Denmark-led trial is novel in that it showed changes in body fat and endocrine/circulatory systems even when caloric intake was matched. This highlights pathways beyond just "overeating," such as food quality, additives, matrix, and contaminants.Cell

What Changes the Body? A Catalog of Hypotheses

• Hyper-palatability: Optimization of sweetness, fat, saltiness, flavor, and texture can lead to rapid eating and overeating. Faster eating speeds up intake before satiety signals kick in.Cell

• Destruction of the Food Matrix: Refining, grinding, and puffing alter digestion speed and glycemic response, affecting insulin dynamics and fat synthesis.

• Interactions of Additives: Emulsifiers and sweeteners may impact the gut environment and mucosa.

• Food Contact Materials and Contaminants: The trial observed increases in **cxMINP (phthalates)**, indicating increased exposure to endocrine-disrupting chemicals.Cell

Still, It Can't Be Black and White: Counterarguments and Nuances

A U.S. research team showed that even with a 90% NOVA UPF ratio, it is possible to design a diet that meets dietary guidelines and is nutritionally "good." In fact, from a nutritional adequacy perspective, rational plans using UPFs can be made. Therefore, **"UPF = immediately unhealthy" is an oversimplification.ARSjn.nutrition.org

At the same time, the calls for refining definitions and identifying mechanisms reflect a **scientific caution that cannot be ignored. Implementing policies with unclear classification and mechanisms could lead to excessive side effects on industries and households.PMCNature

What Is Being Discussed on Japanese Social Media

On X (formerly Twitter), discussions include "posts by healthcare professionals recommending UPF avoidance from the perspective of diabetes and complication risks," "threads visualizing the relationship with mental disorders," and reactions pointing out the "ambiguity of definitions and cost issues," creating a three-way debate. Examples of caution from medical professionals, risk presentation in the mental health domain, and rebuttals to the oversimplification of "processing = bad" can be found.Yahoo!Global Nutrition Group Inc.

This disparity reflects the tug-of-war between the aspect of UPFs supporting "life's UX"—time-saving, cost, and preservation—and the social costs of health and future medical expenses. Internationally, reports linking the spread of UPFs to the worsening of childhood obesity are increasing, and discussions on marketing regulations and school meal standards are heating up.The Guardian

Policy Shifts: WHO Guidance and Labeling/Marketing Regulations

In 2025, the movement to formulate WHO guidance on UPFs was reported, with discussions on strengthening measures against processed meats and sugary drinks and marketing restrictions. While considering scientific uncertainties, the focus is on designing to protect children under the precautionary principle.FoodNavigator.com

What Should We Change? A Practical Guide (From Short to Medium Term)

1) Prioritize "Short Ingredient Lists"

• The guideline is main ingredients + salt, oil, sugar level. Reduce the frequency of products with long additive lists or unfamiliar functional ingredients.

2) Design "Ease of Eating" to Be Weaker

• Bite-sized, crunchy, or just-drink items are easy to consume. Replace with items that require more chewing and are not left at room temperature.

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