Ultra-Processed Foods: A Short Guide to NOVA Group 4 Foods That Make You Overeat

It is 6 p.m. on a weekday, and you stop by the convenience store at the entrance to your neighborhood. You pick up instant noodles, sausage, a bag of snacks, and a soda. It is filling, convenient, and there are no dishes to wash. After age forty, meals like this happen more often than many people realize, because time is short and fatigue is real. These foods are called ultra-processed foods, or UPF. What makes them interesting is that they can make people eat about 500 kcal more per day without realizing it, even when sugar, fiber, and salt are matched.

NOVA: A system for classifying foods by degree of processing

NOVA is a system that classifies foods by degree of processing. It was developed by Prof. Carlos Monteiro and his team at the University of São Paulo in 2009 to 2010. Today, FAO uses it. The idea is to look at how much a food has passed through industrial processing, and whether it contains ingredients that are not found in a home kitchen, such as emulsifiers or hydrogenated oils.

Group	Name	Examples
1	Minimally processed	Vegetables, fresh fruit, fresh meat, eggs, milk, brown rice
2	Culinary ingredients	Oil, butter, salt, sugar
3	Processed foods	Freshly baked bread, cheese, canned fish
4	Ultra-Processed (UPF)	Soda, sausage, instant noodles, packaged snacks

The defining feature of Group 4 is the presence of unnatural ingredients, more than simply counting how many ingredients there are. The phrase “5 or more ingredients” is only a general characteristic, not the main criterion for classification. As for the statement that WHO officially recognizes NOVA, clear evidence has not been found. WHO does reference NOVA, but not to the level of an official endorsement.

UPF makes people eat about ~500 kcal more: RCT-level evidence

The strongest study is by Hall and colleagues, published in 2019 in Cell Metabolism and conducted at NIH. It included 20 participants living in a controlled unit. They alternated between eating a UPF diet and an unprocessed diet, with calories, sugar, fiber, and sodium matched, and were allowed to eat as much as they wanted. The result was that during the UPF period, participants ate 508 ± 106 kcal more per day, gained 0.9 kg, and increased fat mass. During the unprocessed food period, body weight decreased. Hamano’s 2024 crossover RCT also found the same direction of effect.

One caution is that Hall’s study was short, lasting 2 weeks, and included only 20 people. We still do not know whether the effect persists long term. The evidence on insulin resistance and blood pressure comes from cohorts, with type 2 diabetes risk increased at RR = 1.74, so it cannot prove causation 100% because confounding factors may be involved.

Some emulsifiers disrupt the gut, and UPF increases heart risk

Polysorbate 80 (E433) and Carboxymethyl Cellulose (E466) are emulsifiers with detergent-like properties, so they can disrupt the mucus layer that keeps bacteria away from the intestinal wall. Animal research (Nature 2015) found intestinal inflammation and microbiome imbalance. A human RCT (Gastroenterology 2022) gave CMC at 15 grams per day for 11 days and found bacteria encroaching into the inner mucus layer. The caution is that not everyone responds the same way, only some responders did, and the tested dose was higher than typical real-world intake.

On the heart side, UPF is linked with atherosclerosis and CVD risk in multinational studies. A study in Spain (n = 1,876) found that people eating 500 grams of UPF per day had twice the risk of subclinical coronary artery narrowing compared with people eating 100 grams. In UK Biobank (n = 60,298), UPF increased CVD risk by 17% and all-cause mortality by 22%. This is confirmed by at least 4 independent sources without contradiction.

⚠️ thyroid and autoimmune are still only associations

This is the most important point. The claim that UPF causes autoimmune hypothyroidism or demyelination has not been confirmed by any human RCT. What does exist is an observational study from China (n = 8,732) finding that UPF was linked with subclinical hyperthyroidism, an overactive thyroid state that moves in the opposite direction from hypothyroidism, with a 14% increase per SD. Kharrazian’s 2017 work on molecular mimicry was done only in test tubes, and a 2024 systematic review in Frontiers concluded that a causal link still cannot be confirmed. You therefore do not need to panic over headlines that make claims stronger than the evidence supports.

How you can start

3 steps you can take right away

1. Read the ingredient list on the label If you see names such as E433, E466, or names that do not belong in a home kitchen, that is a signal that the food is in Group 4.
2. Move Group 4 foods into the occasional category and make rice, eggs, fresh meat, vegetables, and fruit the foundation of main meals.
3. Record what you eat for 2 weeks Notice your weight, bloating, and energy.

Today, start with just one meal. The next time you stop by a convenience store in the evening, switch from cup noodles and sausage to boiled eggs, plain milk, and one banana. You do not need to quit all processed foods in a single day. Simply bring the foundation of your meals back to real food. If you have thyroid disease or a chronic medical condition, consult your doctor before changing your diet.

This summary is information for understanding only, not medical advice, and should be reviewed by a qualified professional before being put into practice. The full version includes the complete rationale and research