Hunting for the Causes of Obesity, and Maybe Solutions

The chronic disease of obesity is tough to wrap our heads around. On one hand, many people consider themselves to be amateur experts. Consumer media – and our spam folder – is full of glib advice about how to “lose belly fat.” Advice about foods that cause weight gain is everywhere. But the truth is that obesity is not what most people think it is. And the smartest obesity scientists know that boiling the causes of obesity down to a single factor – or even just a few – is a fool’s errand.

Several recent publications give us a more complete and complex view of what is at work when obesity becomes a problem

Looking at Individuals

The most recent perspective comes in the special issue of Nursing Clinics of North America devoted to obesity. Nikhil Dhurandhar, Kristina Petersen, and Chelsi Webster tell us that obesity is an impairment of complex biological systems that regulate energy storage:

“Obesity is a chronic disease with a multifactorial etiology.

“Most factors classified as contributors have an unclear role in ‘causing’ obesity. Nonetheless, in clinical settings, a better understanding of obesity’s causes and contributors may assist in effective weight management.”

Dhurandhar reviews dozens of factors that can cause or contribute to obesity. But this is no different from our knowledge of what causes cancer. Many factors may contribute. Some have a big role. Others have a small role. And it’s different in every person because both cancer and obesity are very heterogeneous conditions. In other words, they come in many different forms.

Likewise, Simone Theilade and colleagues explain that obesity has many causes. But they focus on biological systems. Common obesity results from the interaction of neurologic, endocrine, and metabolic systems with culture, behavior, and genetics. Sometimes there’s a simple cause. A single gene mutation can be at the root. Or a drug can cause weight gain. More often, though, it’s not a single cause. Instead, many factors contribute.

Looking at the Population

Moving to the population level, then, the picture becomes even cloudier. The systems map at the right, from the UK Foresight project, gives you an idea of the complexity. Attempts to pin rising obesity on a single factor or even a few factors are doomed to failure. Worse yet, they delude the public into thinking that simple solutions will reverse a trend that has progressed for decades.

Writing in Nutrition Reviews, Bruce Lee and colleagues tell us that obesity in the population is a problem of complex systems:

“There are a number of indications that the obesity epidemic is a systems problem, as opposed to a simple problem with a linear cause-and-effect relationship. What may be needed to successfully address obesity is an approach that considers the entire system when making any important decision, observation, or change.”

The Cause?

So, as Harry Rutter and colleagues explain, we really need to get over our desire to find the cause of obesity:

“A shift in thinking is required, away from simple, linear, causal models, to consideration of the ways in which processes and outcomes at all points within a system drive change. Instead of asking whether an intervention works to fix a problem, researchers should aim to identify if and how it contributes to reshaping a system in favourable ways.”

Both in the individual and in the population, obesity is a problem of systems gone out of whack. Linear thinking won’t yield solutions. Thinking about the complex systems that are causing it can bring us progress.

It’s time to get curious and dig deeper.

Click here for the Dhurandhar article and here for the paper by Theilade et al.

A Famous Cause, painting by Honore Daumier / WikiArt

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November 11, 2021