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The Obesity Epidemic From a Neuroscience Perspective


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Since the 1970s, there has been an alarming increase in obesity. According to the latest data from the Centers for Disease Control and Prevention (CDC), about 70% of Americans are either overweight or obese. Excess body weight is linked to numerous diseases, including more than 14 types of cancers. There are also substantial economic effects associated with obesity. The CDC estimated the medical costs of prevention, diagnosis, and treatment are estimated at about $150 billion per year in 2008 dollars. This grim situation is getting worse; childhood obesity is at shocking levels, yet it has not taken center stage in health-care debates.

Fad Diets Won’t Solve the Problem

Despite a thriving weight-loss market and busloads of health pundits, there is no solid evidence that any interventions have been able to curb obesity on a population-based level. What is driving this epidemic? Why are so many people susceptible to unhealthy weight gain, and what can be done to reverse this process before our health-care system literally collapses? These grandiose questions are tackled in The Hungry Brain: Outsmarting the Instincts That Make Us Overeat by Stephan J. Guyenet, PhD, a doctor of neurobiology.

Dr. Guyenet has authored many highly cited papers on obesity and is also a nationally regarded speaker in the field of nutrition and health. So, what does he bring to the obesity debate that adds something new? First of all, the simple calories in–calories out formula is cast aside in favor of a neuropsychopharmacologic perspective. His book gets thick with science, but the author writes in such a way that will hold the lay reader’s attention as well.

BOOKMARK

  • Title: The Hungry Brain: Outsmarting the Instincts That Make Us Overeat
  • Author: Stephan J. Guyenet, PhD
  • Publisher: Flatiron Books
  • Publication Date: February 2017
  • Price: $28.95, hardcover, 304 pages

An Obesogenic Environment

Organized in 11 chapters, The Hungry Brain begins by using data to show that the increase in weight gain over the past 40 years is largely driven by a shift in energy balance, as Dr. Guyenet puts it. In other words, we are consuming more calories on a daily basis and expending less energy, causing an increase in adipocytes. This isn’t a news flash, but he certainly makes a convincing argument that an obesogenic environment is public enemy number one.

In short, the availability of inexpensive, high-calorie food that is convenient to prepare and cleverly marketed throws our adaptive reward system into high gear, motivating us to overconsume. Overconsumption plus an indolent lifestyle with little physical work and exercise leads to obesity.

Neural Mechanisms

The author also explores the latest research on how insulin regulates fat storage and the neurotransmitter leptin, which controls appetite along with a dizzying array of neural mechanisms that play integral parts in regulating hunger and preventing fat loss. However, Dr. Guyenet is a neurobiologist, and the title of his book is The Hungry Brain, so readers will expect a lot of brain-related content, and they won’t be disappointed.

In short, the author contends that few Americans really want to overeat, and certainly no one wants to end up obese and suffer the multitude of attendant morbidities. “The conflict between the conscious and non-conscious brain explains why we overeat even though we don’t want to. And even though we try to control our behavior using the conscious parts of our brain, the non-conscious parts work to undermine our good intentions,” Dr. Guyenet writes. Although this is a slightly redundant explanation, which is illustrative of his attempts throughout the book to connect with the lay audience, it comes off with mixed results.

“The conflict between the conscious and nonconscious brain explains why we overeat even though we don’t want to.”
— Stephan J. Guyenet, PhD

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‘The Chemistry of Seduction’

Dr. Guyenet is at his best when he gets down to science, much of which is intriguing. In a chapter called “The Chemistry of Seduction,” the author neatly explains how we humans have developed our cravings and our innate food preferences, which explain why children prefer ice cream to Brussels sprouts or broccoli. It has to do with the ventral striatum, a part of the brain that functions as the reward system.

As far as the ventral striatum is concerned, the fact that Brussels sprouts are super loaded with vitamins and minerals means little to nothing, simply because they don’t deliver calories. “We crave ice cream because our brains know that its flavor and appearance predict a truckload of easily digested fat and sugar. Having evolved in an era of relative food scarcity, the human brain interprets this as highly desirable and draws us toward the freezer.”

This and other theories are fully explicated in chapters that dig deep into the biochemical and behavioral triggers that cause overeating and obesity. Another interesting area is the relationship between sleep loss and eating behavior. According to the author, sleep loss drives us to compensate by eating high-calorie foods. As throughout the book, Dr. Guyenet backs up this assertion with solid data.

The author also supports vigorous regulations on advertisements for unhealthy food that target children. To me, this is the weakest part of the book, largely because of the clout food lobbyists have on Capitol Hill. However, Dr. Guyenet makes a solid argument here.

Obesity is a vital issue with the oncology community, and more is better in the knowledge department. The Hungry Brain is a solid addition to books dealing with this issue, and it is recommended for readers of The ASCO Post. ■


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