The best available evidence says yes, with an important caveat about how strong that evidence is. One randomized controlled feeding trial found that people ate about 500 calories a day more on an ultra-processed diet than on a minimally processed one, even when the two diets were matched for calories, sugar, fat, sodium and fiber. A large umbrella review found consistent associations with worse health outcomes, while grading most of the underlying evidence as low quality.
Both of those things are true at once, and a page that gives you only one of them is not being straight with you. Here is the whole picture.
The controlled trial, which is the interesting one
Nearly all nutrition research is observational: you follow a large group of people, record what they eat, and see what happens. That design cannot separate ultra-processed food from everything else that tends to travel with it, such as income, smoking, exercise and total calories.
In 2019 a team at the National Institutes of Health ran the study that could. Twenty weight-stable adults were admitted to the NIH Clinical Center and randomized to eat either an ultra-processed or an unprocessed diet for two weeks, then immediately switched to the other for two weeks. Every participant served as their own control.
The critical design feature is what the researchers held constant. The two menus were matched for presented calories, energy density, macronutrients, sugar, sodium and fiber. Participants were told to eat as much or as little as they wanted.
| Outcome | Difference on the ultra-processed diet |
|---|---|
| Total energy intake | +508 ± 106 kcal/day (p=0.0001) |
| From carbohydrate | +280 ± 54 kcal/day (p<0.0001) |
| From fat | +230 ± 53 kcal/day (p=0.0004) |
| From protein | -2 ± 12 kcal/day (not significant) |
| Body weight, two weeks | +0.9 ± 0.3 kg, against -0.9 ± 0.3 kg on the unprocessed diet |
Two details are worth sitting with. First, the extra intake came from carbohydrate and fat but not protein, which fits the idea that protein intake is defended more tightly than other macronutrients. Second, weight change tracked energy intake almost perfectly (r=0.8), so this was not a metabolic mystery. People simply ate more.
The honest limitation: twenty people, four weeks in total, in a metabolic ward. It is the only trial of its kind, which is exactly why it carries weight, and it is small. It should not be described as settled proof.
The population evidence, with its own grades attached
A 2024 umbrella review in The BMJ pooled 45 separate meta-analyses covering 9,888,373 people, and applied a formal credibility scheme to each result. Direct associations appeared for 32 of 45 health parameters, or 71 percent.
Below are the findings the authors themselves graded as the strongest. The GRADE column is the part most coverage of this study leaves out, and it is the part a clinician would want.
| Outcome | Effect size | Evidence class | GRADE quality |
|---|---|---|---|
| Cardiovascular disease mortality | RR 1.50 (1.37 to 1.63) | Convincing (class I) | Very low |
| Type 2 diabetes, dose-response | RR 1.12 (1.11 to 1.13) | Convincing (class I) | Moderate |
| Anxiety outcomes | OR 1.48 (1.37 to 1.59) | Convincing (class I) | Low |
| Common mental disorders combined | OR 1.53 (1.43 to 1.63) | Convincing (class I) | Low |
| All-cause mortality | RR 1.21 (1.15 to 1.27) | Highly suggestive (class II) | Low |
| Heart disease mortality | HR 1.66 (1.51 to 1.84) | Highly suggestive (class II) | Low |
| Obesity | OR 1.55 (1.36 to 1.77) | Highly suggestive (class II) | Low |
| Depressive outcomes | HR 1.22 (1.16 to 1.28) | Highly suggestive (class II) | Low |
| Adverse sleep outcomes | OR 1.41 (1.24 to 1.61) | Highly suggestive (class II) | Low |
| Wheezing | RR 1.40 (1.27 to 1.55) | Highly suggestive (class II) | Low |
Read the last column. Of the 45 pooled analyses, 22 were rated low quality, 19 very low, and only four moderate. None were rated high. The authors' own conclusion calls for urgent mechanistic research, which is not the language of a closed case.
This is not a reason to dismiss the findings. Consistency across 45 analyses and almost ten million people is meaningful. It is a reason to describe them accurately: a strong and consistent signal, built mostly on observational data that cannot fully separate ultra-processed food from the lives of the people eating it.
A finding that complicates the simple story
If ultra-processed food were simply a proxy for sugary drinks, the trend data would show them rising together. They do not.
An analysis of twenty years of national nutrition survey data covering 33,795 American children and teenagers found that calories from ultra-processed food rose from 61.4 percent to 67.0 percent between 1999 and 2018. Over exactly the same period, calories from sugar-sweetened beverages fell by half.
| Share of total calories | 1999 | 2018 | Change |
|---|---|---|---|
| All ultra-processed foods | 61.4% | 67.0% | +5.6 points |
| Unprocessed or minimally processed foods | 28.8% | 23.5% | -5.3 points |
| Ready-to-heat and ready-to-eat mixed dishes | 2.2% | 11.2% | +8.9 points |
| Sweet snacks and sweets | 10.7% | 12.9% | +2.3 points |
| Sugar-sweetened beverages | 10.8% | 5.3% | -5.5 points |
The category that grew fivefold is ready-to-heat and ready-to-eat mixed dishes: the frozen entree, the microwave bowl, the packaged lunch kit. That is the most actionable line in the whole dataset and it is almost never quoted.
What this evidence does not say
It does not identify a mechanism. Candidates include the speed at which soft, low-fiber food can be eaten, the additives themselves, effects on the gut microbiome, and simple energy density, and the research has not settled among them.
It also does not license a claim that any particular food prevents or treats disease. Associations between an eating pattern and outcomes across a population are not a promise about an individual, and no food should be sold as though they were.
What follows practically
The most defensible reading is that displacement matters more than avoidance. In the twenty-year trend data, ultra-processed calories rose and minimally processed calories fell by almost exactly the same amount. Adding minimally processed food to a day is a more tractable goal than eliminating a category, and it is the version of this advice that survives contact with a normal week.
For the practical version, see how to eat less ultra-processed food without cooking more, which includes a swap table and what our own customer data says about which changes people sustain. For the definitions behind all of this, see what counts as ultra-processed food. If you are working out what to eat instead, see how many vegetables you actually need a day and what actually happens if you do not eat vegetables.
SaladPower is six whole organic vegetables and fruits with nothing added, which places it in the minimally processed group rather than the ultra-processed one. That is a fact about our ingredient list, not a health claim.
Frequently asked questions
Is there proof that ultra-processed food causes weight gain?
There is one randomized controlled trial. Twenty adults ate 508 calories a day more and gained 0.9 kg on an ultra-processed diet, then lost 0.9 kg on a minimally processed one, with the diets matched for calories, sugar, fat, sodium and fiber. That is causal evidence in a small sample rather than proof at population scale.
How strong is the evidence linking ultra-processed food to disease?
Consistent but mostly low quality. A 2024 BMJ umbrella review of 45 meta-analyses covering almost ten million people found associations with 32 of 45 health outcomes. Under GRADE, 22 of those analyses were rated low quality, 19 very low and four moderate. None were rated high.
Which health outcomes have the strongest evidence?
Cardiovascular disease mortality, type 2 diabetes, anxiety and combined common mental disorders were the four graded as convincing. Type 2 diabetes is the only one of those whose underlying evidence was rated moderate quality rather than low or very low.
Is it the additives or just the calories?
Unknown. The controlled trial matched the two diets on calories, sugar, fat, sodium and fiber, and people still ate more on the ultra-processed one, so it is not only a matter of nutrient content. Candidate explanations include eating rate, texture, energy density, additives and effects on the gut microbiome. The researchers themselves called for urgent mechanistic work.
Do I need to eliminate ultra-processed food entirely?
Nothing in this literature tests elimination. The trend data suggest displacement is the more useful frame: over twenty years, ultra-processed calories rose 5.6 points while minimally processed calories fell 5.3 points. Adding minimally processed food is a more achievable change than removing a whole category.
Sources
- 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 Metabolism. 2019;30(1):67-77.e3. doi:10.1016/j.cmet.2019.05.008
- 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. doi:10.1136/bmj-2023-077310
- Wang L, Martínez Steele E, Du M, et al. Trends in consumption of ultraprocessed foods among US youths aged 2-19 years, 1999-2018. JAMA. 2021;326(6):519-530. doi:10.1001/jama.2021.10238
- Rico-Campà A, Martínez-González MA, Alvarez-Alvarez I, et al. Association between consumption of ultra-processed foods and all cause mortality: SUN prospective cohort study. BMJ. 2019;365:l1949. doi:10.1136/bmj.l1949
- Srour B, Fezeu LK, Kesse-Guyot E, et al. Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). BMJ. 2019;365:l1451. doi:10.1136/bmj.l1451
- Monteiro CA, Cannon G, Lawrence M, Costa Louzada ML, Pereira Machado P. Ultra-processed foods, diet quality, and health using the NOVA classification system. Rome: FAO; 2019. Full text (PDF)
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