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NOVA (not a acronym) is the food classification that categorizes foods based on the degree and purpose of food processing, rather than their nutritional content. It was developed in 2009 by a research group at the University of São Paulo in Brazil[2].

NOVA classifies foods into four groups based on the nature, extent, and purpose of the industrial processing they undergo.

(1)Unprocessed or minimally processed foods
Fresh fruits and vegetables, and other natural foods (such as grains, milk, fish, and meat) that have undergone processes like removing inedible parts, drying, grinding, pasteurization, chilling, freezing, or vacuum-packaging.

(2)Processed culinary ingredients
Substances derived from Group 1 foods or from nature through processes that include pressing, refining, milling, or drying, such as oils, butter, sugar, and salt. These processed culinary ingredients are typically not consumed on their own.

(3)Processed foods (PFs)
These are typically made by adding Group 2 substances to Group 1 foods. Examples include canned vegetables, fruit in syrup, canned fish, cheese, and freshly made breads.

(4)Ultra-processed foods (UPFs)
These are formulations created by combining many ingredients and undergoing a sequence of industrial processes. Examples include breakfast cereals, soft drinks and fruit juices, sweet or savory snacks, confectioneries, instant foods, reconstituted meat products such as sausages and nuggets, and most fast food items[3,4].

Food processing, in essence, refers to “various operations by which raw foodstuffs are made suitable for consumption, cooking, or storage,” and virtually all foods undergo some form of processing before being eaten. Therefore, processing itself is not inherently bad. 

However, ultra-processed foods are not modified foods but formulations made mostly or entirely from substances derived from foods and additives through multiple industrial processes, with little to no Group 1 natural foods[3].

UPFs are highly appealing because they are hyper-palatable and addictive, inexpensive, have a long shelf life, and can be consumed anytime, anywhere[3].

The evidence based on the NOVA classification so far suggests that the decline in minimally processed foods and home cooking, alongside the replacement of food supplies with ultra-processed foods, is associated with unhealthy nutritional profiles and an increase in several diet-related diseases[3].

In studies on adults reporting the proportion of total daily energy intake from UPFs, the highest levels (on average) were reported in the USA (55.1–56.1%), followed by the UK (53–54.3%), Canada (45.1–51.9%), France (29.9–35.9%), Brazil (20–29.6%), Spain (24.4%), and Malaysia (23%)[6].

A cross-sectional study (2005–2014) on American adults, who were found to consume an average of  56.1% of their total energy intake from UPFs, revealed significant differences across quintiles. Those in the highest quintile (Note 1) consumed 84.5% of their total energy intake from UPFs, while those in the lowest quintile accounted for 25.4%[7]. 

 (Note 1: Quintile refers to one of five equal measurements that a set of things can be divided into)

♦A cross-sectional time series study conducted in fifteen Latin American countries revealed that sales of UPFs were associated with changes in body weight in twelve of these countries from 2000 to 2009[8].

A cross-sectional study based on data from Brazil’s 2008–2009 Household Budget Survey found that household availability of UPFs was positively correlated with both the average BMI and obesity prevalence. Those in the highest quartile (Note 2) of household consumption of UPFs were 37% more likely to be obese compared to those in the lowest quartile[9]. 

(Note 2: Quartile refers to one of four equal measurements that a set of things can be divided into)

♦A study involving 6,143 participants from the UK National Diet and Nutrition Survey (2008–2016) classified foods recorded in four-day food diary according to the NOVA system. Consumption of UPFs was associated with increases in BMI, waist circumference, and obesity rates in both men and women. For every 10% increase in UPF consumption, the obesity rate increased by 18%. 

Higher consumption of UPFs was observed among men, white British individuals, smokers, younger people, and those in lower social class groups[10].

♦A cross-sectional study involving 19,363 adults aged 18 and older from the 2004 Canadian Community Health Survey, found that individuals in the highest quintile of UPF consumption were 32% more likely to be obese compared to those in the lowest quintile. Higher UPF intake was associated with being male, younger age, lower educational attainment, physical inactivity, smoking, and being born in Canada[4].

♦A prospective cohort study conducted since 1999 among graduates of the University of Navarra in Spain tracked 8,451 participants who were not overweight at baseline for about nine years. Those in the highest quartile of UPF consumption had a 26% higher risk of developing overweight or obesity compared to those in the lowest quartile.

Moreover, on average, they consumed more fast food, fried foods, processed meats, and sugar-sweetened beverages, while, in contrast, their vegetable intake was the lowest. A higher consumption of UPFs was associated with lower adherence to the Mediterranean diet[11].

♦A U.S. research group analyzed data on 5,919 children and 10,064 adults from the National Health and Nutrition Examination Survey (2015-2018) to investigate the relationship between UPF consumption and overall diet quality. Diet quality was assessed using the American Heart Association (AHA) diet score and Healthy Eating Index (HEI)-2015 score.

The research group concluded that higher consumption of UPFs was associated with substantially lower diet quality among children and adults. These findings were consistent with previous studies conducted in several countries[12].

♦An Italian research group hypothesized that meal timing could also be linked to food processing and conducted a study to test this. They analyzed data on 8,688 individuals from the Italian Nutrition & Health Survey (INHES), conducted between 2010 and 2013. Subjects were classified as early or late eaters based on the population’s median timing for breakfast, lunch, and dinner.

Results showed that late eaters (breakfast after 7 AM, lunch after 1 PM, and dinner after 8 PM) were less likely to consume unprocessed or minimally processed foods compared to early eaters, while they consumed more processed foods (PFs) and UPFs. Late eating was also inversely associated with adherence to the Mediterranean diet[13].

The Mediterranean diet, which primarily consists of fruits, vegetables, legumes, nuts, olive oil, and fish, has been shown to be linked to reduced weight gain[14].

A group of researchers in the U.S. conducted a crossover comparative study to ascertain the net energy intake of two different diets: one consisting of specific processed foods and the other of an isocaloric whole-food (WF) diet. Eighteen subjects consumed two types of sandwiches with the same calorie content but differing in processing levels.

The WF meal consisted of multigrain bread (containing whole sunflower seeds and whole-grain kernels) and cheddar cheese, while the PF meal consisted of white bread and a processed cheese product.

In this study, diet-induced thermogenesis (DIT)(Note 3) after consuming the PF meal was 46.8 % lower than that of the WF meal. The researchers concluded that this difference in DIT led to a 9.7 % increase in net energy-gain for the PF meal[15].

(Note 3)  Diet induced thermogenesis (DIT) is the process by which the body increases its energy expenditure for several hours in response to food intake.

Regarding the significant reduction in diet-induced thermogenesis (DIT) observed with the PF meal, the researchers provided the following analysis:

Compared to whole foods, PFs are characterized by lower nutrient density (a lower content and diversity of nutrients per calorie), less dietary fiber, and an excess of simple carbohydrates. As a result, PFs are structurally and chemically simpler than whole foods, making them easier to digest[15,16].

A group of U.S. researchers conducted a randomized controlled trial to determine the effects of ultra-processed versus unprocessed diets on ad libitum energy intake in twenty adults with stable body weight. Subjects were randomly assigned to either the ultra-processed or calorie-matched unprocessed diet for two weeks, followed by the alternate diet for another two weeks.

In this experiment, participants were allowed to eat additional food after meals. As a result, they consumed more energy (459±105 kcal /day) during the ultra-processed diet and gained 0.4±0.1 kg of body fat. In contrast, they lost 0.3±0.1 kg of body fat during the unprocessed diet.

Fasting blood tests showed that levels of the appetite-suppressing hormone peptide YY (PYY) increased during the unprocessed diet as compared with both the ultra-processed diet and baseline. Also, levels of the hunger hormone ghrelin decreased during the unprocessed diet compared to baseline. This suggests that participants felt less hungry during the unprocessed diet, whereas the ultra-processed diet provided less satiety, making participants feel hungrier[19]. 
           

I would like to explain the link between consumption of UPFs and an increase in obesity from the perspective of intestinal starvation.

Since the development of the NOVA classification, various studies have focused on the degree of food processing rather than calorie content, which is noteworthy.

Through this blog, I have explained that a combination of factors—such as an unbalanced diet leaning toward refined carbohydrates and UPFs, a lack of vegetables, and an irregular lifestyle—can induce intestinal starvation, potentially raising the body's set-point weight.

UPFs are often high in energy density, so they are generally believed to promote obesity when overeaten. However, I believe the biggest issue is the "ultra-processing" itself, as these foods are digested and absorbed more quickly than natural foods.

If the diet is skewed toward refined carbohydrates and UPFs, and the overall diet quality declines, blood sugar levels can fluctuate sharply. Additionally, since these foods leave nothing behind in the intestines after digestion, intestinal starvation can be triggered (Note 5).

The fact that adherence to the Mediterranean diet and the consumption of natural foods like vegetables are inversely correlated with obesity supports my perspective.

In Japan, In my opinion, the consumption of UPFs such as instant foods, cookies, sweet bread, and chocolate confection is not necessarily low. However, one reason Japan’s obesity rate is lower than in Western countries may be its rice-based food culture, and the fact that many Japanese people still follow traditional eating habits. 

(Note 5: Foods high in fat, such as ice cream, take longer to digest and may help prevent intestinal starvation.)

The World Obesity Federation (WOF) warns that if policy directions remain unchanged and no effective measures are taken to prevent and treat obesity, more than half of the global population will be classified as overweight or obese by 2035.

I think this suggests that past policies focused solely on "calories in/ calories out" have not been particularly effective. 

What we need now is a shift in focus from "calories" to factors such as the degree of food processing, the number of chews, and digestibility in policymaking.

However, many people today prefer soft foods that require little chewing and have become overly reliant on refined carbohydrates and UPFs. These diets are low in nutrients and fiber, making them easy to digest, allowing the body to absorb large amounts of energy with minimal effort.

Moreover, once all the food is fully digested in the intestines, a signal that “there is no food” might be sent to the brain.

Such dietary habits were likely rare, if not nonexistent, in human history—at least until around 1970. It is not an overstatement to say that the sharp rise in being overweight, obesity, and many lifestyle-related diseases coincided with the rapid industrialization of food in the 1970’s and 80’s.
               

<References>
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[14]Beunza JJ et al. Adherence to the Mediterranean diet, long-term weight change, and incident overweight or obesity: the Seguimiento Universidad de Navarra (SUN) cohort.  Am J Clin Nutr. 2010 Dec;92(6):1484-93. 

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[20] World Obesity Federation.