By Mario Kratz, PhD
Published March 31, 2022
Last updated on April 17, 2022
Today, we will take a close look at the emergence of what is often called the twin epidemics of obesity and type 2 diabetes. This twin epidemic has been taking place all over the world over the last 30-40 years, and it is still getting worse. We will examine the changes in diet that have occurred during this same time frame in several different affected populations. We will see some patterns emerge of specific changes in the diets of these populations that have almost certainly played a major role in the massive changes in body weights and metabolic health.
The Obesity and Diabetes Epidemics in the United States
Let’s start with the United States as our first example. As recently as 1985, obesity was not really a major issue of concern. Even though this was the first year that the US Centers for Disease Control and Prevention (the CDC) started issuing this map here to display the obesity prevalence in each state, most states had no data on this. Those states for which data were available mostly showed that less than 10% of adults were obese, with only some states showing a prevalence between 10 and 14%.
Just 5 years later, this picture had shifted, and another 5 years later, a new color had to be added for states with a prevalence between 15 and 19% range. As you can see in the maps above, new colors to represent ever higher prevalence rates had to be added to the map regularly, reflecting an extremely rapid increase in the percentage of U.S. adults who were becoming obese. The rate of increase has slowed down since, but the most recent data from 2017/2018 show that 42% of all American adults are obese.
Now, that’s a major health concern because being obese dramatically increases the risk to develop type 2 diabetes. The graph above shows that the risk of developing diabetes in a woman with a BMI of more than 35 is about 93 TIMES higher than that of a woman with a BMI of less than 22. In those that are obese (BMI of more than 30), the risk is at least 26-times higher than in those in the lowest weight category. This is just one study, but the data in numerous other studies confirm that there is a very strong and consistent link between having excess body fat mass and a substantially increased risk of type 2 diabetes.
Considering the rise in the obesity prevalence, and the strong association between BMI and diabetes risk, it is not astonishing then that the prevalence of diabetes has also increased several fold in this same time frame. The increase since the late 1950s shown in the graph above is really scary. Most recent data that I could find, published by the CDC, show a prevalence of 10.5% for 2018, a total of 34.2 Million Americans.
As recently as in 2001, when the prevalence was 4%, researchers estimated that the prevalence may reach 7.2% by the year 2050. Well, look at this graph above again: we reached 7.2% in 2015, 35 years earlier than predicted! More recent analyses for the year 2050 now estimate that one in three adult Americans will have diabetes in 2050, and considering the recent trajectory, that number doesn’t seem crazy.
Nutrition Transitions - General Overview
These dramatic changes in the prevalence of obesity and diabetes among the US population obviously raise the question: what happened with our diet and lifestyle that caused this?
There are undoubtedly several factors at play here, including more sedentary lifestyles, but one big thing that has almost certainly been a major driver of the obesity epidemic is one of the biggest nutrition transitions in the history of humankind.
In general, when we talk about nutrition transition, what we mean is that a population, either an entire country or a population within a country, substantially changes its diet over time. Dr. Barry Popkin is a leading researcher in this field who has published many good papers on nutrition transitions and the role of the changing food environment, including a very recent one on which the categorization of different dietary patterns and nutrition transitions is based.
As probably most of you know, for most of their time on earth, humans were Hunters and Gatherers, and so the first diet pattern that researchers have identified is commonly called “Collecting Food”. So this is the food pattern of all people before the advent of agriculture about 10,000 years ago, but we can certainly still find such Hunters and Gatherers in fairly modern times, such as the Inuit (prior to 1950/60) or certain indigenous tribes in the Amazon or Afrika. This pattern is characterized by people eating a diverse mix of wild plants and animal foods that are unprocessed. Hunting and collecting food is labor-intensive, so this life is active, and as a result, people are lean and robust. Life expectancy is low though because of high mortality during childbirth, infectious diseases, and accidents.
The very first nutrition transition is the move to agriculture, that is, a transition to the second pattern, which is commonly referred to among scientists as “Famine”. That is because while people in this pattern grow food, they struggle to regularly get enough calories. Many times, meals are based mostly on cooked grains with little variety in terms of other plant or animal foods. Growing food in this pattern is still very labor-intensive, so people are active, but they often don’t get enough to eat. This pattern is therefore characterized by both regular famines and also general micronutrient deficiency. As a result, the life expectancy of people following this dietary pattern is low.
The second nutrition transition happens when agriculture starts to provide more abundance, both in terms of producing enough calories and also in terms of providing more variety in both plant and animal foods. This allows people to obtain enough calories and also to meet most or all of their micronutrient needs. In this third pattern, commonly called ‘receding famine’, the majority of the food available to most people is still starchy from either grains or tubers such as potatoes or sweet potatoes, and animal foods make up a relatively small proportion of the diet. In this pattern mortality risks decline and life expectancy increases due to an overall better nutritional status.
So, pattern 1 refers to diets characterized by Hunting and Gathering, and patterns 2 and 3 refer to diets based on small- or medium-scale agriculture. Note how in all of these three patterns, the food is typically unprocessed or only minimally processed, like milk is fermented to make yogurt and cheese, or grains are baked into bread.
Now it’s going to get real interesting because now we are going to talk about pattern 4, and that is the pattern that we in the United States and many other “Western” countries such as Canada, Australia or those in Western Europe have been transitioning into over the last, let’s say 30 to 40 years. That transition may have started more than 100 years ago, but the change has really accelerated in the last 30 to 40 years. And that pattern is commonly referred to among researchers as “Chronic Disease”. Yes, I am not joking …
This transition is characterized by major shifts in the entire food system, specifically the industrialization of both agriculture and food processing. Typical for this transition is also the adoption of mass media such as TV or the internet, and much more exposure to advertisements, including for food.
Now, to clarify, in Western Europe or North America, the populations have more or less gone through these patterns from 1 through 4 chronologically over the last 10,000+ years. However, some populations around the world are now going directly from being Hunters and Gatherers to having access to industrialized foods. The Inuit of Alaska and Canada are good examples, and we’ll talk about these more further below. In again other regions of the world, we now have some rural populations that remain in the famine or receding famine stage while the wealthy urban elite is also transitioning into the fourth diet pattern called ‘chronic disease’.
Let’s take a closer look at what dietary changes this new diet pattern has brought that we have transitioned into in the United States and most Western countries. And, by the way, even if you are not living in North America, Western Europe, Australia, or New Zealand, you are likely living in a country that is experiencing some level of this transition right now, so I think this is equally relevant for everyone to understand.
The Nutrition Transition in the United States
Unfortunately, the data we have to address this question are pretty poor, because they are either survey data, which means they are based on self-report, or country-level food availability data, which is not exactly reflective of what individual people actually eat. But I do think they give us some pretty solid ideas of what has happened.
The first thing we may want to consider is whether the macronutrient composition of the American diet has changed. We have data from repeated surveys of a representative sample of Americans from the National Health and Nutrition Examination Survey (NHANES) for the entire time frame that seems most relevant here, starting in 1970 when the obesity prevalence in the US was still fairly low.
This first set of figures here show the changes in macronutrient intake among adult men and women between 1970 and the year 2000. We see a clear trend in both men and women of slightly increased carbohydrate and reduced fat intake, as a percentage of total calories consumed. During this time, the obesity prevalence roughly doubled, so many people have attributed this rise to increasing carbohydrate consumption.
However, when we look at more recent data for the time frame from 2000 to 2016, we see that carbohydrate intake (in percent of total energy intake) has declined again. During this time, the obesity prevalence continued to rise and actually almost doubled again, so this is not consistent with the idea that increased carbohydrate intake is the principal driver of the obesity epidemic in the United States.
Next, let’s take a look at shifts in the types of food eaten between 1970 and 2014. The data in the graph below are based on total food availability. We can see the increase in carbohydrate intake reflected here as well, particularly in the increased consumption of grains, but there has also been a pretty substantial increase in added fats and oils, from 337 kcal per person per day to 562 kcal per person per day. Also, based on this, total energy intake has increased in this time frame by almost 400 kcal per person per day, so even though fat intake as a percentage of total energy intake may have declined, absolute fat intake has probably not gone down.
Now, this graph suggests that there hasn’t been much of a change in most categories, such as fruit and vegetables, dairy, added sugars, as well as the meat, eggs, and nut category.
If we look at these food availability data in a different way though, we see major shifts in the consumption of some of these food categories (see figure below). For example, among meats, beef consumption has declined a lot between 1970 and 2014, but chicken consumption has increased a lot. Beet and cane sugar consumption has decreased, but corn sweeteners, so high fructose corn syrup, has increased a lot to make up for that reduction. Milk, particularly whole milk intake has declined, but cheese intake has increased. And among grains, corn products have gone up a lot.
Now, to try to figure out which of these shifts in the American diet best explain the explosion in obesity and diabetes, we could look at each of these categories by themselves, and many researchers have done that.
In this paper from 2004, for example, Drs. Bray, Nielsen, and Popkin proposed that the increase in high-fructose corn syrup consumption may have played a role in the epidemic of obesity. The figure I posted below from this paper shows clearly how high-fructose corn syrup consumption has increased from basically nothing in 1970 to about 90 g per person per day in the year 2000, during the time frame when the prevalence of obesity has roughly doubled.
Now, for sure, eating this much of a simple sugar cannot be good for anyone’s waistline or health. But, while some scientists were trying to place all of the blame on higher fructose consumption or specifically high-fructose corn syrup, others felt that other factors were more likely to blame. Maybe it was the massive increase in the consumption of vegetable oils, most of which are rich sources of omega-6 fatty acids, leading to a shift in the ratio of omega-6 to omega-3 unsaturated fatty acids that somehow may have changed our appetites. Again others thought that overeating and therewith the obesity epidemic could most plausibly be explained by changes in the energy density of food, or maybe food had gotten more rewarding or even more addictive over time. Again others speculated that overeating may be an attempt of the body to meet its requirements for essential micronutrients, possibly as a response to a reduction in the micronutrient content of our foods.
I’d say, all of these are, more or less, interesting ideas, and I followed this debate with a lot of interest over the last 20 or so years. With my group, I have even published a few papers and made some modest contributions to these very attempts to try to figure out the one factor, the one nutrient, or the one food that made America gain so much weight.
Well, we still don’t have conclusive evidence which factor or factors are the most critical ones, but I feel that a major step forward has been made fairly recently when we realized that all of the proposed diet changes that were suspected to contribute to the obesity epidemic are actually linked. And that critical link is the way our foods are produced and particularly the way they are processed.
In other words: the dietary change that has predisposed Americans, and as we will see, the entire world, to gain body weight at a historically unprecedented rate is a lot bigger than can be explained by looking at any one single dietary factor. Let me explain.
Let’s take a look at some of the main food categories the consumption of which has increased since 1970. Increased vegetable oils, increased high-fructose corn syrup, and increased ‘corn products’ in particular can tell us a lot about what has been going on here. How do people consume these foods? Are we chugging more than an ounce of soybean oil or cottonseed oil per person per day at home? That’s just the amount of increase since 1970, by the way. Are we buying jugs of high-fructose corn syrup to use in our home baking? And how often do you buy unprocessed ‘corn products’?
What the increased availability of these foods in our food system indicates is the rise of fast food and particularly the rise of industrially manufactured so-called ultra-processed foods.
You may have heard the term ultra-processed foods, but if you haven’t, let’s clarify this briefly. Ultra-processed food refers to “Industrial formulations of foods with typically 5 or more and usually many ingredients”. Major components of ultra-processed foods are salt, sugar (or I add high-fructose corn syrup), oils and fats, but also a long list of ‘substances not commonly used in culinary preparations’. These include hydrolyzed proteins, modified starches, hydrogenated oils, artificial sweeteners, artificial colors, artificial flavors, emulsifiers, and firming, de-foaming, anticaking, and glazing agents. And many others.
The term ultra-processed food was coined in 2009 by a Brazilian colleague, Dr. Carlos Monteiro, when he proposed that the the degree of processing is a major determinant of the health effects of a food.
Well, what are examples of ultra-processed foods? A good example would be a commercially-produced donut. See a typical ingredient list below: here you find the vegetable oils, the sugar, and a lot of other “substances not commonly found in culinary preparations”. These types of donuts are basically a refined grain with sugar or high-fructose corn syrup, fried in vegetable oil, but then further ‘enhanced’ in a factory to be even more irresistible than your normal homemade donut.
Other typical ultra-processed foods include flavored potato chips, flavored corn chips, sweetened and/or colorful breakfast cereals, certain types of ice cream, and even factory-produced packaged bread. Actual ingredient lists from products currently available for sale in the United States are posted below.
When looking at it like this, realizing how many – let’s be honest – absurd products we’ve allowed the food industry to serve us, I think you will realize that it is important to consider this entire huge shift in our food system and our diet, rather than trying to find the one nutrient, or the one food that caused the obesity epidemic. What has happened is so much bigger than people eating more sugar, chicken, or vegetable oil. We are now daily exposed to dozens of foods that were specifically designed to make us eat more and more, because that’s the only way the food industry could get us to buy more and more.
To really understand what has happened, we need to realize why and how all of these ultra-processed food products have been developed. You see, the managers in the food industry didn’t sit in a room and contemplated how they could make us more healthy by creating better food. They discussed how they could make bigger profits: how could they produce more cheaply and sell more?
So what they did is two things. The first was place a lot of adds for their ‘foods’: check out the green line here in this graph below that shoots up like a rocket just before the obesity epidemic is starting in earnest. The second was to industrially design foods to be irresistible, or as we sometimes call them today, hyperpalatable. Hyperpalatable doesn’t just mean yummy. It’s the kind of yummy that – whether you want it or not – makes you get a second serving, or the entire package. That has without doubt been good for sales numbers, but I think more and more emerging data strongly suggests that it has also had some – eh – side effects on consumers.
Well, the topic of industrially designed, hyperpalatable foods is something we’ll definitely talk about again in the future, but for today, I guess you all realize what I am talking about when I say these foods are hyperpalatable. An excellent book on this topic, by the way, is Michael Moss’s Salt, Sugar, Fat with the subtitle How the Food Giants Hooked Us.
Let’s actually look at some concrete data on ultra-processed food consumption in the United States. This table below shows that currently, ultra-processed foods probably provide somewhere between 50 and 60% of total calories in the US. There are a couple studies that come up with lower or higher estimates, but most studies found ultra-processed food consumption (UPF, last column) in the 50-60% range.
We also know that this number has increased in recent years. Two recent publications show clearly that ultra-processed food intake has increased in both children and adults in the last 20 years. Unfortunately, however, ultra-processed food consumption had already been quite high around the year 2000, and we don’t have any good data that I am aware of that provides an estimate of ultra-processed food consumption in the 1970s or earlier, you know, before the obesity epidemic began in earnest. That’s probably the biggest gap in our argument that ultra-processed foods have been and still are the major driver of the obesity epidemic.
So you may wonder, why do I suggest that increased consumption of ultra-procecessed foods has played a role in the obesity epidemic? Well, even though we don’t have solid data on ultra-processed food intake 50 years ago, I think it’s certain that a lot less ultra-processed food was eaten in the 1970s, prior to the rapid rise in the obesity prevalence. Sure, people were eating some breakfast cereal, a donut, or ice cream or drinking a soda once in a while, but if you look at the cereals, donuts, or ice cream from around that time, these would not necessarily be considered ultra-processed foods today. I am not saying these were health foods at the time, but they almost certainly were not the type of industrially-designed hyperpalatable foods that are so ubiquitous today. The degree of processing has undoubtedly increased substantially over the last 50 years, and so has the variety of different types of ultra-processed foods. My best guess is that Americans were probably getting around 10 or 20% of their calories from ultra-processed foods in the 1950s to 1970s. That would be similar to what we are seeing in Italy, Portugal, or Spain today (see below). But, admittedly, that’s a guess and not good, hard data, so let’s look at some other evidence to put the hypothesis to the test that ultra-processed foods may be a major culprit in the obesity epidemic.
The Nutrition Transition Towards More Ultra-Processed Foods in Other Countries
Now, what increases my confidence a lot that the nutrition transition towards more ultra-processed foods has played a causal role in increasing prevalence of obesity and type 2 diabetes is the fact that very similar observations have been made in dozens of other countries and populations around the world. Let’s take a look at a few of them.
This publication from 2012, for example, outlines the changes in diet and obesity prevalence in 42 developing countries between 1990 and 2010. The food environment has been changing rapidly in these countries, with many similarities between these countries. One notable change was that more and more grocery stores were opened, giving people more access to ultra-processed foods. In parallel, incomes rose which meant that more money was available to purchase ultra-processed foods. People also increased their consumption of added sugars, refined grains, and added fats and oils, i.e., all of the main ingredients of ultra-processed foods. They also increased their consumption of animal foods, but reduced their intake of whole grains, legumes, and vegetables.
Associated with these dietary changes, these countries were, and in most cases still are, experiencing changes in the percentage of adults that are overweight or obese, similar to what has happened in the US in the past 30-40 years. This figure below, for example, shows that in those 42 developing countries, the obesity prevalence has increased, on average by 0.5 percentage points in women living in rural areas, and by 0.8 percentage points in women living in urban areas, PER YEAR. Unfortunately, this paper did not directly quantify changes over time in ultra-processed food consumption in relation to the emergence of the obesity epidemic in these countries, but the description of the qualitative changes in relation to rapidly rising rates of obesity is another data point in support of the idea that increased consumption of ultra-processed foods is a key driver of weight gain.
To directly assess whether the obesity epidemic is generally more advanced in countries with greater adoption of ultra-processed foods, I took a look at countries for which we have data on ultra-processed food intake as well as obesity prevalence. I picked some countries that have low, some that have intermediate, and some that have high intakes of ultra-processed foods, and then looked at the obesity prevalence in each.
Now, this does look like quite a compelling association. Also, a side note for those of you who think that changes in carbohydrate intake are the major driver of the obesity epidemic, take a look at Italy here. As anyone who has ever been to Italy knows, Italians love not just pasta and pizza, but also risotto, polenta, gnocchi, and a particularly crusty white bread. And Italian soda and ice cream are famous in the entire world. Their carbohydrate intake, as a percentage of total calories, is actually 48%, which is pretty similar to the US, yet obesity prevalence in the country is 12%. I’d say that’s a point in favor of the idea that ultra-processing of food is a major culprit, rather than shifts in macronutrient intakes, because ultra-processed foods account for only 12% of all calories consumed in the country.
Remember though that these types of ecological observational data are fairly poor and subject to a lot of limitations. Also, to get a more complete picture, we’d have to look at many more countries, which would then pose some methodological problems because we don’t have similarly good data on ultra-processed food intake for most countries. Also, as soon as we include Asian countries, we would need to consider that obesity is defined differently among Asian populations.
From this graph, let’s just conclude that among the larger Western countries, there seems to be a compelling association between the consumption of ultra-processed foods and the prevalence of obesity. This doesn’t prove that there is a cause-effect relationship, but these data do provide some additional support for the hypothesis that ultra-processed foods MAY play a role in the development of weight gain and obesity.
In addition to comparing countries in terms of their consumption of ultra-processed foods in relation to the overall obesity prevalence, we can also look inside any one country and ask whether those individuals who consume the most ultra-processed foods have a higher body mass index and a higher risk of being obese.
The table below is from a 2020 paper showing that yes, indeed, among people in the United Kingdom, those in the highest quartile of ultra-processed food intake have a 90% higher likelihood of being obese than those in the lowest quartile, with a nice trend accross the quartiles. This analysis (model 2 in the table below) is adjusted for physical activity, age, and other major risk factors for obesity.
Very similar data were obtained in a Brazilian study. This one grouped people into quintiles, not quartiles, based on their ultra-processed food intake. Again, we are seeing that the risk of being obese is 97% higher in the fifth quintile, which means in the 20% with the highest ultra-processed food intake, compared to the first quintile. And again, this is after adjustment for major risk factors for obesity and other dietary factors.
The Nutrition Transition in Alaskan Inuit and Pima Indians
The nutrition transition can also affect a specific population within any given country.
A particularly interesting example are the Inuit populations of Alaska or Northern Canada. In both places, agriculture is impossible, and people there rely heavily on hunting. Traditionally, their diets consisted of meat such as venison and fowl, or hunted seafood from whale, walrus, seals, or fish. Occasionally, eggs or berries would be gathered. Now, I am not claiming this is an ideal diet, and there are some indications that Inuit on this diet had health problems, including low-bone mineral density leading to osteoporosis as well as atherosclerosis leading to heart disease. However, obesity and type 2 diabetes were not common in these populations until the 1950s or 60s. The data below, for example, show that the mean body mass index for almost all of these Inuit populations were in the normal range in the 1950s.
As some of the Inuit villages became accessible by plane, convenience stores opened that carried processed foods with a long shelf life: white flour or foods made from it, such as white bread, crackers, or cookies; soda; sugar; potato chips; candy; vegetable oils; and margarine. In other words, the very definition of ultra-processed foods. And the consumption of these foods has increased ever since.
For example, traditional foods accounted only for 22% of total calories consumed in 2007 in a community of Yup’Ik Eskimos in Western Alaska. If you look at this population categorized into quintiles based on their traditional food intake, we see that some of these Inuit are no longer consuming traditional foods. These are mostly the younger ones, while traditional food intake remains fairly high among the older generation. As one would expect, the fewer traditional foods are consumed, the more energy is consumed, and also the more carbohydrates.
I personally know several of the researchers working in these communities, and the consequences of this shift are predictable bad. Apparently, in some communities, the entire family drinks sugar-sweetened beverages all day, and as a result, many teenagers do not have any (healthy) teeth left. Obesity has risen dramatically, and even type 2 diabetes has been affecting more and more people. According to this 2007 paper, the average body mass index of this particular Inuit community is now higher than that of the US population. At the time of this study, the obesity prevalence was 32%, and the diabetes prevalence was 3.3%. Both have almost certainly increased further since 2007.
Let’s contrast this to a different population, namely that of the PIMA Indians in Mexico as compared to those living in the US. This 2006 paper here described that the Pima Indians in Mexico are living in a very remote mountainous region that had just recently become accessible by road. As a result, industrially-proceessed food was basically not available in these communities, and they were still in the agricultural, unprocessed food stage we discussed earlier called ‘receding famine’. That means they worked their farms and both men and women were physically very active, and their diet consisted primarily of traditional Mexican food centered around beans and corn. Their diet was quite low in fat and high in complex carbohydrates and fiber.
The situation was very different in the U.S. Pima. Due to very sad and – if you read up in this history a little bit – quite upsetting circumstances that had to do with access to water, farming had become gradually impossible for the US Pima living in Arizona, and they became more and more dependent on government funds to purchase normal US foods, which we now know are to a large degree ultra-processed.
I guess you can imagine what the results of these very discrepant diets and lifestyles are. The Pima are known to be genetically susceptible to obesity, and so even on their traditional diet and lifestyle, 6.5% of the men and 19.8% of the Mexican Pima men and women, respectively, were suffering from obesity. Compare that to the US Pima though, with an obesity prevalence of 63.8% among men and 74.8% among women.
As for type 2 diabetes, 35% of men and 42% of women had diabetes among the US Pima, with the prevalence hovering around 6-8% for the Mexican Pima.
I wanted to share these two examples because in both cases, we have an indigenous population living their traditional lifestyle and eating their traditional diets. In the case of the Inuit, this was a diet very rich in animal foods, fats, and protein, whereas in the case of the Mexican Pima, the diet was very high in complex carbohydrates and fiber and very low in fat. Very very different diets, with almost no overlap, but what they shared was that both traditional diets were unprocessed or only minimally processed. And while obesity and type 2 diabetes were not entirely absent when these populations were consuming these traditional diets, the prevalence of both was fairly low. Both of these peoples had far more problems with obesity and diabetes once they were exposed to factory-produced ultra-processed foods. I also feel this is another example suggesting that the critical change is the one towards more ultra-processed foods, not a change towards more carbs or more fats, because the changes in macronutrient intakes that coincided with the rise in obesity in these two populations could not have been more different from one another in this regard: the Inuit started eating a lot more carbs, but the Pima started eating a lot more fat.
Evidence that Ultra-Processed Foods Increase Ad Libitum Energy Intake
I think I have made my point that wherever we look, the more ultra-processed foods people consume, the more they tend to struggle with weight problems and the higher the prevalence of obesity is. Don’t we have more direct evidence, you may ask? Yes, we do, there is one particular study that is highly relevant to this discussion. But that is such a cool and important study, and there is so much to say about it, that this post here would get way too long (let’s be honest, it already is too long …). For example, we will want to take a more thorough look at what a diet rich in ultra-processed foods looks like, and also discuss through which mechanisms ultra-processed foods may trigger overeating. So, I am going to devote a separate post to that study, which will probably be ready in a couple of weeks or so. If your interest has been peaked as to whether our collective struggle with excessive body weight may be linked to ultra-processed foods, make sure you sign up for our newsletter below so that I can let you know whenever new content is up. Just as a little teaser: the study we are going to talk about is a controlled feeding trial, and produced very interesting results that clearly support the hypothesis put forth here in this blog post that ultra-processed foods may be a key factor in the obesity epidemic.
Let’s summarize what we learned from looking at these different examples of the global nutrition transition.
In populations all over the world, as the food pattern has shifted towards greater consumption of ultra-processed foods, the prevalence of obesity and associated health problems such as type 2 diabetes has skyrocketed. Now, to reiterate, there is currently no conclusive evidence that ultra-processed foods are the cause of the obesity epidemic, but I would say it’s a strong hypothesis with lots of evidence piling up in its favor.
We have also discussed how ultra-processed foods are characterized by several dietary factors that in and of themselves are linked to overeating. These include high-fructose corn syrup when consumed in the form of a sweetened beverage, a higher energy density due to the addition of fats or oils, hyperpalatability, or any of the many non-culinary substances that are routinely added to ultra-processed foods. A lot of research is currently ongoing to figure out whether it’s indeed ultra-processing of foods that make us overeat and gain weight, or if its a combination of some of these associated factors. My guess us that the hyperpalatability of ultra-processed foods is a big factor for sure, i.e., the fact that these foods are designed to make us eat more. Greater consumption of caloric beverages in the form of soda or energy drinks, and greater energy density are also plausible additional contributing factors. I’ll make sure to report on any new key findings in this area.
The Next Nutrition Transition
Most of the world is currently fully in the nutrition transition from pattern 3, ‘receding famine’, which is an agricultural food system with mostly unprocessed or minimally processed foods, to pattern 4, ‘chronic disease’, which is characterized by ultra-processed foods. Well, this doesn’t need to be the last transition. In fact, researchers have already proposed that the next transition could be characterized less by systemic changes in our food environment and more by individual actions each of us makes individually. That pattern 5 has been coined ‘behavioral change’, and I am suggesting that anyone who has understood that the current transition towards more and more ultra-processed food will make us all sick should feel invited to escape the long-term negative health consequences of this dietary pattern by removing as much ultra-processed foods as possible from their diet. Give it a try, just observe for a few days how many ultra-processed foods you regularly eat, and think about how that could be changed. Sure, ultra-processed foods are convenient, relatively inexpensive per calorie, and hyperyummy, but they also wreak havoc on our health.
Convenience versus health; shouldn’t be a difficult decision. But then, I do understand that it can be quite difficult in practice to stay away from ultra-processed foods. Let’s try our best, let’s support each other in our efforts, and let’s try to work together to move the food system away from absurd concoctions that are designed to make us obese and sick. And let’s not be too hard on ourselves and others if we struggle with overeating; this is a difficult battle against a food industry that has invested gobs of money to get us to eat more and more against our best intentions. It is a system that was not designed to support our biology but to exploit our evolutionary weaknesses, and if there is one thing obesity research has shown over the last few decades it is that it is difficult for anyone to avoid overeating in this obesogenic food environment.
- United States Centers for Disease Control and Prevention. Adult Obesity Prevalence Maps. Accessed on March 30, 2022.
- Boyle et al.; Projection of diabetes burden through 2050. Diabetes Care 2001; 24: 1936-40.
- United States Centers for Disease Control and Prevention. National Diabetes Statistics Report 2020. Estimates of Diabetes and Its Burden in the United States. Accessed on 03/25/2022.
- Popkin and Ng. The nutrition transition to a stage of high obesity and noncommunicable disease prevalence dominated by ultra-processed foods is not inevitable. Obesity reviews 2022; 23: e13366.
- United States Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey. Accessed on March 30, 2022.
- Shan et al.; Trends in dietary carbohydrate, protein, and fat intake and diet quality among US adults, 1999-2016. JAMA 2019; 322: 1178-87.
- Pew Research Center. What’s on your table? How America’s diet has changed over the decades. Accessed on March 30, 2022.
- Bray et al.; Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. Am. J. Clin. Nutr. 2004; 79: 537-43.
- Simopulos and DiNicolantonio. The importance of a balanced omega-6 to omega-3 ratio in the prevention and management of obesity. Open Heart 2016; 3: e000385.
- Mendoza et al.; Dietary energy density is associated with obesity and the metabolic syndrome in U.S. adults. Diabetes Care 2007; 30: 974-9.
- Berthoud et al.; Food reward, hyperphagia, and obesity. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2011; 300: R1266-77.
- Astrup and Bügel. Micronutrient deficiency in the aetiology of obesity. Int. J. Obes. 2010; 34: 947-48.
- Gibney. Ultra-processed foods: definitions and policy issues. Curr. Dev. Nutr. 2019; 3: nzy077.
- Monteiro. Nutrition and health. The issue is not food, nor nutrients, so much as processing. Publ. Health. Nutr. 2009; 12: 729-31
- Bentley et al.; Obesity, metabolism, and aging: a multiscalar approach. Prog. Mol. Biol. Transl. Sci 2018; 155: 25-42.
- Michael Moss. Salt Sugar Fat – How the Food Giants Hooked Us. 2014 Random House, New York.
- Marino et al. A systematic review of worldwide consumption of ultra-processed foods: findings and criticisms. Nutrients 2021; 13: 2778.
- Wang et al.; Trends in consumption of ultraprocessed foods among US Youths aged 2-19 years, 1999-2018. JAMA 2021; 326: 519-30.
- Juul et al.; Ultra-processed food consumption among US adults from 2001 to 2018. Am. J. Clin. Nutr. 2022; 115: 211-21.
- Popkin et al.; Global nutrition transition and the pandemic of obesity in developing countries. Nutr. Rev. 2012; 70: 3-21.
- USDA Agricultural Research Service. Consumption of Pizza. February 2014. Accessed on 03/25/2022.
- Statista. Statistics about the obesity prevalence in Italy in 2020. Accessed March 30, 2022.
- Australian Government. Australian Institute of Health and Welfare. Overweight and obesity: an interactive insight. Accessed on March 30, 2022.
- OECD. State of Health in the EU. Country Health Profile 2019: Spain. Accessed on March 30, 2022.
- Rauber et al. Ultra-processed food consumption and indicators of obesity in the United Kingdom population (2008-2016). PLOS One 2020; 15: e0232676.
- Da Costa Louzada et al.; Consumption of ultra-processed foods and obesity in Brazilian adolescents and adults. Prev. Med. 2015; 81: 9-15.
- Young. Are the circumpolar Inuit becoming obese? Am. J. Human Biol. 2007; 19: 181-9.
- Bersamin et al.; Nutrient intakes are associated with adherence to a traditional diet among Yup’Ik Eskimos living in remote Alaska native communities: the CANHR study. Int. J. Circumpolar Health 2007; 66:1.
- Mohatt et al.; The Center for Alaska Native Health Research Study: a community-based participatory research study of obesity and chronic disease-related protective and risk factors. Int. J. Circumpolar Health 2007; 66:1.
- Schulz et al.; Effects of traditional and Western environments on prevalence of type 2 diabetes in Pima Indians in Mexico and the U.S. Diabetes Care 2006; 29: 1866-71.