The obesity epidemics: another problem we don't know how to solve

A suburban market near Florence, Italy, a few days ago. This market is frequented only by local residents and it provides good evidence that the Italians, on the average, are not so fat. Most people you see walking there are in reasonably good shape and I tried hard to find someone truly obese, but I didn't see a single one.  It turns out that, indeed, Italy is less affected by obesity than most (although not all) countries of the Western World. But things are rapidly changing; Mediterranean diet notwithstanding, even in Italy people are more and more gaining weight and becoming obese. The obesity epidemic seems to be another one of those problems that keep getting worse and that we just don't know how to solve. 

We all know that the world suffers an obesity epidemic, hitting in particular the rich countries of the West. But what exactly makes people fat? You could say that it is because they eat too much and exercise too little and that would be, obviously, true. But should fat people be demonized because they can't control their appetite? Being overweight, and, in particular, being obese, brings all sorts of health problems; being also told that it is your fault just adds further misery to an already painful condition (*). Yet, this is a common attitude (See DeShazo et. al.). But consider that a whole scientific field has been developed with the specific purpose of creating food so tasty that people can't stop eating it. And we have a whole industry, the food industry, dedicated to making people eat more, and another, the medical industry, trying to make them eat less. A no win situation, if ever there was one.

There is more to say about the damage done by the modern, hypertechnological food industry. Food is not only a question of how many calories it contains, but also of the nutrients it contains. And there is a reason why we often use the term "junk food"; it is because this food contains plenty of calories, but few nutrients (see also this post of mine). So, it may be that people try to compensate for the lack of nutrients by eating more food; another likely reason for the obesity epidemic (see, e.g.  Swinburn et al.). Obese people are actually malnourished (see, e.g. Hyman).

But there may be more to this story if we consider the situation from a "systemic" viewpoint. Human beings are complex systems and complex systems are known to react in a non-linear manner to external forces. So, facing an obese person, if you are thinking in terms of systems, you won't just say "this person eats too much". Rather, you would ask, "what could have unbalanced the metabolic homeostasis of this person?"

To illustrate this point, let me compare the obesity epidemics to climate change (that we could call a "high temperature epidemic"). The Earth's atmosphere is a typical complex system that reacts in a strongly non linear manner to external perturbations (called, usually, "forcings"). The main forcing causing global warming is the increase in the concentration of the greenhouse gas carbon dioxide, CO2. It is not the only forcing agent, but surely the most important one in unbalancing the atmospheric homeostasis.

Note how all it takes is a small increase in CO2 concentration (little more than a hundred parts per million) to generate a major change in the atmospheric temperatures. It is a point that many people find difficult to understand; not unexpectedly because we are not used to think in systemic terms. But even a small change in the complex atmospheric system can generate a cascade of reinforcing feedbacks that create the disaster we call "climate change." That's the way complex systems work.

Now, could it be that something similar is taking place with the obesity epidemic? Could there be a single agent, or, anyway, a main one, that triggers a cascade of reinforcing metabolic feedbacks that turn normal human beings into land whales?

It can't be excluded, but identifying such a substance, if it exists, is a major - nearly impossible - task. A recent review by Simmons et al. reports a table of 23 putative obesogen substances, chemicals that go from heavy metals to saturated fat, including pesticides, hormones and more. And then the same authors report a table of 38 more possible obesogen additives, but never tested in this sense. A grand total of 61 possible additives that could make you fat; and I am sure that there are many more not listed in the paper.

The sheer number of possible culprits makes one's head spin.  But, in a sense, that can be seen also as promising. What if one of these chemicals plays the role of CO2 in the atmosphere? That is, could one of them be the main trigger of obesity? It would be great if we could point to a specific substance and say: "Look! This is the stuff that makes people obese! Stop putting it into the food we eat!" And, from then on, we would see no more land whales in shopping malls.

Unfortunately, things are not so simple. As I said, the human metabolic system is much more complex than the climate system and, therefore, it is hard to identify such a substance, assuming it exists. The best that can be done is to test the possible obesogens one by one, but what if their effects are reinforced by feedbacks created by their combination? To return to the climate example, by examining the climate system, we could conclude that water vapor is one of the causes of global warming, because it is a greenhouse gas and it is abundant in the atmosphere. But, no, the increase of water vapor concentration is not the cause of global warming, it is an effect of it. We can say that because we know the climate system much better than the human metabolic system.

Then, even if we could identify one or more substances that play a major role in triggering obesity, it may be impossible to remove them from food. Stuff such as heavy metals are just all around us; we have been creating or extracting them over centuries of industrial activity. There is no way to remove them completely from the ecosystem.

And, finally, even if we manage to have scientific proof that a specific substance is the main cause of obesity, we would likely see the food industry gearing up for a major denial campaign. It is easy to imagine politicians stating, "Look, I am not a scientist, but I believe that there is no proof that bis-tetraphenil-dyazin-watchamacallit causes obesity." and then you would hear in the news, "Fatgate: food scientists confess they have faked the obesity data in order to keep their research grants!"  And so on.....

In the end, it seems that the problem with obesity is the same we have with other gigantic problems we face: climate change, the food supply and many others. Often, we are not smart enough to understand what causes them and, even if we do, we are, unfortunately, smart enough that we can stop all attempts to solve them. It seems that we are creating a world so complex that it is becoming impossible for us to manage it.

Let me conclude, however, with a note of optimism (of a sort). Obesity has the advantage over climate change that people can experiment with it by themselves. So, a lot of different diets are being tried, from Vegan to Paleo, and everything in between. With all this experimenting going on, eventually we'll learn something about what makes people fat and how to avoid it. This is, after all, the way the universe manages complex systems: it just discards what doesn't work; it is called natural selection. It would be nice if we could apply the same strategy to climate change; too bad that we have just one planet.




(*) The author of this post has a body mass index (BMI) of 26.2, and that puts him on the lower side of overweight. 

h/t Roberto Rondoni