In two randomised feeding trials, ultra-processed diets led to more eating and weight gain (Hall 2019) or less weight loss than minimally processed diets with the same guideline targets (Dicken 2025). Cohorts link ultra-processed food to many outcomes, though certainty is often low. Crop nutrient decline is real but modest: US data for 43 crops show median falls of 6% to 38% in 6 of 13 nutrients from 1950 to 1999, probably from breeding for yield. Rising carbon dioxide lowers plant minerals by about 8%.
Summary drafted from this entry’s sources; editorial review pending.
01Key questions
Is there trial evidence that ultra-processed food causes weight gain?
Yes, from two small trials. In an NIH inpatient crossover trial, people ate 508 more calories a day and gained weight on an ultra-processed diet. In a UK crossover trial, both diets met guidelines but weight loss was about twice as large on the minimally processed one.12
How strong is the evidence linking ultra-processed food to disease?
Consistent but mostly observational. An umbrella review of 45 pooled analyses found associations with 32 outcomes, but rated certainty for cardiovascular death very low. In NutriNet-Santé, each 10% more ultra-processed food tracked 12% higher cancer risk.34
Have fruits and vegetables really lost their nutrients?
Some, for some nutrients. US data for 43 garden crops show reliable median declines for 6 of 13 nutrients between 1950 and 1999, from 6% for protein to 38% for riboflavin. Most single-food changes were within the noise, and the authors pointed to crop varieties bred for yield.5
Two separate claims travel together: that ultra-processed food harms health, and that whole food itself has lost nutrients. The first now has two randomised feeding trials behind it as well as a large observational literature, though most of the evidence is still observational. The second is real for some nutrients in some crops, but smaller and less certain than the popular "vegetables have lost most of their minerals" line, and part of it is a side effect of breeding for yield. Rising carbon dioxide is a separate, better-measured mechanism.
02Ultra-processed food: the trials
- NIH inpatient trial. Twenty adults lived at the NIH Clinical Center and ate an ultra-processed or an unprocessed diet for two weeks each, in random order, eating as much as they wanted. Meals were matched for presented calories, energy density, macronutrients, sugar, sodium and fibre. On the ultra-processed diet they ate 508 more calories a day and gained 0.9 kg; on the unprocessed diet they lost 0.9 kg (Hall 2019, PMID 31105044).
- UK guideline-diet trial. Fifty-five adults with overweight or obesity ate two eight-week diets that both followed the UK Eatwell Guide, one minimally processed and one ultra-processed. Both led to weight loss, but loss was about twice as large on the minimally processed diet (2.06% against 1.05% of body weight; difference 1.01 percentage points) (Dicken 2025, PMID 40760353). Processing mattered even when the nutrient targets were the same.
03Ultra-processed food: the cohorts
- Umbrella review. Across 45 pooled analyses covering almost 10 million people, higher ultra-processed food exposure was directly associated with 32 of 45 health outcomes. Evidence was graded convincing for cardiovascular death (risk ratio 1.50), type 2 diabetes, anxiety and common mental disorders, but GRADE certainty for cardiovascular death was very low (Lane 2024, PMID 38418082). The gap between "convincing" and "very low certainty" is the honest summary: consistent associations, hard to separate from everything else about people who eat a lot of these foods.
- Cancer. In the French NutriNet-Santé cohort, each 10% increase in the share of ultra-processed food in the diet was associated with 12% higher overall cancer risk and 11% higher breast cancer risk, and the link held after adjusting for fat, sodium, carbohydrate and a Western dietary pattern (Fiolet 2018, PMID 29444771).
- Who paid. One author of the NIH trial disclosed food-industry speaking fees and consortium funding from Abbott Nutrition, Nestec and Danone, and authors of the umbrella review are affiliated with a centre funded partly by a diet-meal company and two dairy firms. See the who-paid box and who funds nutrition research.
04Are vegetables less nutritious than they used to be?
- What the data show. Comparing US Department of Agriculture food composition data for 43 garden crops in 1950 and 1999, after adjusting for water content, Davis and colleagues found statistically reliable median declines for 6 of 13 nutrients, from 6% for protein to 38% for riboflavin, with calcium, phosphorus, iron and vitamin C in between, and no reliable change for the other 7 (Davis 2004, PMID 15637215).
- The caveats in the same paper. For individual foods, most changes could not be distinguished from zero with the available data, and about 28% of the reliable changes were increases. The authors' best explanation for real declines was crop varieties bred for yield, a trade-off sometimes called the dilution effect, rather than depleted soil.
- Carbon dioxide. A meta-analysis of 7,761 observations across 130 plant species and cultivars found that elevated carbon dioxide lowers overall mineral concentrations in C3 plants by about 8% (Loladze 2014, PMID 24867639). Field trials at the carbon dioxide levels expected by mid-century found lower zinc and iron in C3 grains and legumes and less protein in C3 grains other than legumes, with C4 crops less affected (Myers 2014, PMID 24805231).
05What follows
- The case against ultra-processed food no longer rests only on cohorts, but the two trials are small and short, and they measure intake and weight, not disease.
- Nutrient decline in whole foods is real for some nutrients and modest in size. It is a reason to care about crop varieties and diversity, not a reason to think vegetables have stopped being worth eating.
- Claims that modern produce has lost most of its minerals usually go beyond these data.
Related: optimal human nutrition, seed oils, the sugar industry papers. This page summarises research; it is not dietary advice.
06Who paid, and how it got here
Who funded the key studies on this page, the favourable and the unfavourable alike, and how its legal status came about. From each paper’s funding and conflict-of-interest statements, trial registries and official documents; checked 1 Nov 2026. Why we show this
Who paid for the key studies
- Hall 2019, inpatient randomized crossover trial, n=20; author interestsUltra-processed food increased calorie intake and body weight.Funding and interests: Forde disclosed food-industry speaking reimbursements, Kerry advisory work, and consortium funding from Abbott Nutrition, Nestec and Danone. Conflict-of-interest statement
- Lane 2024: umbrella review, 45 pooled analyses; n=9,888,373Higher ultra-processed food exposure tracked multiple adverse health outcomes.Funding and interests: Authors’ Food & Mood Centre received Be Fit Food, Bega Dairy and Drinks, and a2 Milk Company support. Conflict-of-interest statement
07Connections
08Sources
- Hall KD, Ayuketah A, Brychta R et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77. PMID 31105044PubMed 31105044
- Dicken SJ et al. Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nat Med. 2025. PMID 40760353PubMed 40760353
- Lane MM, Gamage E, Du S et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024;384:e077310. PMID 38418082PubMed 38418082
- Fiolet T, Srour B, Sellem L et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort. BMJ. 2018;360:k322. PMID 29444771PubMed 29444771
- Davis DR, Epp MD, Riordan HD. Changes in USDA food composition data for 43 garden crops, 1950 to 1999. J Am Coll Nutr. 2004;23(6):669-82. PMID 15637215PubMed 15637215
- Loladze I. Hidden shift of the ionome of plants exposed to elevated CO2 depletes minerals at the base of human nutrition. eLife. 2014;3:e02245. PMID 24867639PubMed 24867639
- Myers SS, Zanobetti A, Kloog I et al. Increasing CO2 threatens human nutrition. Nature. 2014;510(7503):139-42. PMID 24805231PubMed 24805231
09Entry history
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Heretic informs and never prescribes. Where amounts appear, they describe what published studies used. Talk to a qualified clinician before acting on anything here.