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Arguments For Calling Obesity A Disease #2: It Is Driven By Biology



feastContinuing in my miniseries on reasons why obesity should be considered a disease, I turn to the idea that obesity is largely driven by biology (in which I include psychology, which is also ultimately biology).

This is something people dealing with mental illness discovered a long time ago – depression is “molecules in your brain” – well, so is obesity!

Let me explain.

Humans throughout evolutionary history, like all living creatures, were faced with a dilemma, namely to deal with wide variations in food availability over time (feast vs. famine).

Biologically, this means that they were driven in times of plenty to take up and store as many calories as they could in preparation for bad times – this is how our ancestors survived to this day.

While finding and eating food during times of plenty does not require much work or motivation, finding food during times of famine requires us to go to almost any length and risks to find food. This risk-taking behaviour is biologically ensured by tightly linking food intake to the hedonic reward system, which provides the strong intrinsic motivator to put in the work required to find foods and consume them beyond our immediate needs.

Indeed, it is this link between food and pleasure that explains why we would go to such lengths to further enhance the reward from food by converting raw ingredients into often complex dishes involving hours of toiling in the kitchen. Human culinary creativity knows no limits – all in the service of enhancing pleasure.

Thus, our bodies are perfectly geared towards these activities. When we don’t eat, a complex and powerful neurohormonal response takes over (aka hunger), till the urge becomes overwhelming and forces us to still our appetites by seeking, preparing and consuming foods – the hungrier we get, the more we seek and prepare foods to deliver even greater hedonic reward (fat, sugar, salt, spices).

The tight biological link between eating and the reward system also explains why we so often eat in response to emotions – anxiety, depression, boredom, happiness, fear, loneliness, stress, can all make us eat.

But eating is also engrained into our social behaviour (again largely driven by biology) – as we bond to our mothers through food, we bond to others through eating. Thus, eating has been part of virtually every celebration and social gathering for as long as anyone can remember. Food is celebration, bonding, culture, and identity – all features, the capacity for which, is deeply engrained into our biology.

In fact, our own biology perfectly explains why we have gone to such lengths to create the very environment that we currently live in. Our biology (paired with our species’ limitless creativity and ingenuity) has driven us to conquer famine (at least in most parts of the world) by creating an environment awash in highly palatable foods, nutrient content (and health) be damned!

Thus, even without delving any deeper into the complex genetics, epigenetics, or neuroendocrine biology of eating behaviours, it is not hard to understand why much of today’s obesity epidemic is simply the result of our natural behaviours (biology) acting in an unnatural environment.

So if most of obesity is the result of “normal” biology, how does obesity become a disease?

Because, even “normal” biology becomes a disease, when it affects health.

There are many instances of this.

For example, in the same manner that the biological system responsible for our eating behaviour and energy balance responds to an “abnormal” food environment  by promoting excessive weight gain to the point that it can negatively affect our health, other biological systems respond to abnormal environmental cues to affect their respective organ systems to produce illnesses.

Our immune systems designed to differentiate between “good” and “bad”, when underexposed to “good” at critical times in our development (thanks to our modern environments), treat it as “bad”, thereby creating debilitating and even fatal allergic responses to otherwise “harmless” substances like peanuts or strawberries.

Our “normal” glucose homeostasis system, when faced with insulin resistance (resulting from increasingly sedentary life circumstances), provoke hyperinsulinemia with ultimate failure of the beta-cell, resulting in diabetes.

Similarly, our “normal” biological responses to lack of sleep or constant stress, result in a wide range of mental and physical illnesses.

Our “normal” biological responses to drugs and alcohol can result in chronic drug and alcohol addiction.

Our “normal” biological response to cancerogenous substances (including sunlight) can result in cancers.

The list goes on.

Obviously, not everyone responds to the same environment in the same manner – thanks to biological variability (another important reason why our ancestors have made it through the ages).

But, you may argue, if obesity is largely the result of “normal” biology responding to an “abnormal” environment, then isn’t it really the environment that is causing the disease?

That may well be the case, but it doesn’t matter for the definition of disease. Many diseases are the result for the environment interacting with biology and yes, changing the environment could indeed be the best treatment (or even cure) for that disease.

Thus, even if pollution causes asthma and the ultimate “cure” for asthma is to rid the air of pollutants, asthma, while it exists, is still a disease for the person who has it.

All that counts is whether or not the biological condition at hand is affecting your health or not.

The only reason I bring up biology at all, is to counter the argument that obesity is simply stupid people making poor “choices” – one you consider the biology, nothing about obesity is “simple”.

@DrSharma
Edmonton, AB

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