Ultra-Processed Foods
Ultra-processed Foods (UPFs) featured article
Ultra-processed foods (UPFs) have quietly taken over modern diets, making up nearly 60% of the average American's daily intake. Unlike whole or minimally processed foods, UPFs are industrial formulations packed with additives, artificial ingredients, and refined sugars and fats designed to enhance taste and shelf life—but at a significant cost to health. These foods don't just contribute to obesity and metabolic disorders; emerging research shows they actively rewire the brain, altering decision-making, impulse control, and reward processing in ways that drive overeating. Incredibly, studies reveal that even five days on a high-calorie UPF diet can impair white matter integrity in the brain, diminish reward sensitivity, and increase liver fat by 63%, all without noticeable weight gain.
The real danger of UPFs isn't just their calorie content but their ability to disrupt metabolic and neurological pathways before visible signs of disease appear. By altering insulin signaling...
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Modern diets are often dominated by ultra-processed foods, yet scientists still debate whether their harm stems from high calories or the industrial processing itself. To test this, researchers at the University of Copenhagen conducted a tightly controlled crossover study in healthy men.
The study enrolled 43 men aged 20 to 35, each randomized to two 3-week diet phases with a 12-week break between them. Both meal plans had the same calories, macronutrients, and timing, but differed sharply in composition: the ultra-processed version supplied about 77 percent of calories from packaged or industrially refined products, while the unprocessed plan contained less than 1 percent. One study arm received adequate calories based on estimated energy expenditure and the other received 500 kcal per day in surplus.
Key results showed that processing level, not just calories, shaped health outcomes:
- Men gained about 1.3 to 1.4 kilograms on the ultra-processed diet (UPD) compared with the unprocessed diet (UD), despite matched calories and similar estimated intake within arms.
- In the calorie-matched condition, total cholesterol and the LDL-to-HDL ratio increased relative to the unprocessed diet, both signs of worse lipid balance. Those on the surplus-calorie plan saw higher diastolic blood pressure.
- In the surplus-calorie UPD arm, growth differentiation factor-15 (GDF-15) decreased relative to the UD, a mitochondrial stress signal that normally promotes energy expenditure and appetite suppression, while leptin levels trended upward relative to the UD, reflecting greater fat mass and satiety signaling. In the adequate-calorie UPD arm, thyroid hormones (T3 and TSH) trended higher, changes consistent with subtle alterations in metabolic rate regulation.
- Follicle-stimulating hormone (FSH) decreased in the surplus-calorie UPD arm relative to the UD, a hormone essential for supporting sperm development. Testosterone and total sperm motility tended to decline, though sperm count was stable.
- In the adequate-calorie arm, interleukin-4 (IL-4) increased on the UPD relative to the UD, while C-reactive protein and the oxidative stress marker 8-oxo-dG showed no changes.
Because calories and macronutrients were matched and estimated intake was similar within arms, the findings indicate effects attributable to processing level itself. The researchers suggest several explanations, including that ultra-processed foods may deliver more usable energy or influence hormones that regulate appetite and metabolism. Packaging chemicals and additives might also contribute through subtle endocrine effects.
The short, three-week duration and reliance on participant adherence limit firm conclusions, but the pattern suggests that reducing heavily processed foods could benefit both metabolic and reproductive health. Longer trials will be needed to see whether these changes persist and how quickly they reverse when people return to whole-food diets. In this clip, I explain how ultra-processed foods impact appetite, inflammation, and long-term disease risk. )