Nonprofit, nonpartisan journalism. Supported by readers.

UCare generously supports MinnPost’s Second Opinion coverage; learn why.

Carbs as culprit: Could obesity be a cause, not a consequence, of overeating?

Potato chips
“The increasing amount and processing of carbohydrates in the American diet has increased insulin levels, put fat cells into storage overdrive and elicited obesity-promoting biological responses in a large number of people,” Ludwig and Friedman explain.

Is obesity a consequence or a cause of overeating?

For more than a century, we’ve been told that it’s the former — specifically, that we get fat because we eat too much and exercise too little.

In other words, maintaining a healthy weight is all a matter of having enough willpower.

But, as two obesity experts note in an article published online Sunday in the Journal of the American Medical Association (JAMA) and in a more reader-friendly commentary published the same day in the New York Times, research now suggests that we may have been looking at obesity from the wrong viewpoint.

“What if we’ve confused cause and effect?” ask Dr. David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital, and Mark Friedman, director of research at the Nutrition Science Initiative in San Diego, California. “What if it’s not overeating that causes us to get fat, but the process of getting fatter than causes us to overeat?”

“According to this alternative view,” they write, “factors in the environment have triggered fat cells in our bodies to take in and store excessive amounts of glucose and other calorie-rich compounds. Since fewer calories are available to fuel metabolism, the brain tells the body to increase calorie intake (we feel hungry) and save energy (our metabolism slows down). Eating more solves this problem temporarily but also accelerates weight gain. Cutting calories reverses the weight gain for a short while, making us think we have control over our body weight, but predictably increases hunger and slows metabolism even more.”

This may explain why so few people who lose pounds on calorie-reduction diets can maintain that weight loss for any significant length of time.

“For both over- and under-eating, these responses tend to push weight back to where it started — prompting some obesity researchers to think in terms of a body weight ‘set point’ that seems to be predetermined by our genes,” write Ludwig and Friedman.

Count carbs, not calories

But if those set points are genetically predetermined, why have obesity rates only skyrocketed in recent decades?

Because of a shift in our dietary habits, suggest Ludwig and Friedman. Over the past 30 years or so, we have been devouring ever-increasing amounts of highly refined (and quickly digestible) carbohydrates, often because those carbs been added to processed foods to take the place of dietary fat (which we’ve been told is our nemesis in the weight-loss battle).

That trend has had a devastating effect.

“The increasing amount and processing of carbohydrates in the American diet has increased insulin levels, put fat cells into storage overdrive and elicited obesity-promoting biological responses in a large number of people,” Ludwig and Friedman explain. “Like an infection that raises the body temperature set point, high consumption of refined carbohydrates — chips, crackers, cakes, soft drinks, sugary breakfast cereals and even white rice and bread — has increased body weights throughout the population.”

One of Ludwig’s own studies found that people burn an average of about 325 more calories per day on a low-carb than on a low-fat diet — about the same amount of energy that’s expended in an hour of moderate-intensive physical activity.

Entrenched interests

Scientists have yet to prove that obesity is a cause, not a consequence of overeating, but research seems to be heading in that direction. If the hypothesis is correct, “it will have immediate implications for public health,” write Ludwig and Friedman. “It would mean that the decades-long focus on calorie restriction was destined to fail for most people. Information about calorie content would remain relevant, not as a strategy for weight loss, but rather to help people avoid eating too much highly processed food loaded with rapidly digesting carbohydrates.”

In other words, instead of being told to reduce the quantity of our food, we’d be advised to improve its quality.

Of course, such a paradigm shift in our thinking about obesity will not happen overnight, no matter how strong the evidence becomes. It’s up against some powerful entrenched-interest headwinds. To begin with, most people like the calorie-in-calorie-out theory. It has an attractive simplicity that is both easy to grasp and that puts the blame for our obesity epidemic on individuals rather than on the institutions that grow, package and market our foods.

We seem to live in times when blaming individuals for social problems is not only fashionable, but has become a kind of blood sport.

And most members of the food and beverage industry would like to keep it that way. After all, the continued emphasis on calories serves Big Food’s economic interests, even if it doesn’t serve the economic interests of the rest of us. (The annual health costs related to obesity in the United States is now around $200 billion, or about 21 percent of all medical expenditures in the country.)

“The food industry — which make enormous profits from highly processed products derived from corn, wheat and rice — invokes calorie balance as its first line of defense,” write Ludwig and Friedman. “If all calories are the same, then there are no bad foods, and sugary beverages, junk foods and the like are fine in moderation. It’s simply a question of portion control. The fact that this rarely works is taken as evidence that obese people lack willpower, not that the idea itself might be wrong.”

You can read the two obesity experts’ New York Times commentary on that newspaper’s website. If you prefer a more scholarly take on the topic, you’ll find their JAMA article on that journal’s website.

Comments (7)

  1. Submitted by Susan Lesch on 05/20/2014 - 10:33 am.

    Hold on

    Friedman works for Gary Taubes who cofounded the Nutrition Science Initiative. Harriet Hall recently responded to Mr. Taubes.

    Dr. Fuhrman is on the right track. Please forgive me if I mischaracterize his most recent book, “The End of Dieting”. On page 90 to 91 basically he says to Americans, get off your butts and take responsibility for your diet. “Eating right is the right thing to do.”

    I have no patience for Ludwig and Lustig and Friedman and Taubes. According to J. Morris Hicks, we have less than 2 acres of arable land to feed each person on Earth. Let’s do that.

  2. Submitted by Rick Prescott on 05/20/2014 - 12:31 pm.

    No “patience”?

    “I have no patience for Ludwig and Lustig and Friedman and Taubes.”

    In saying that, you are admitting that you have no patience for actual science.

    The calories-in-calories-out model has virtually no scientific basis, and a significant amount of scientific (and observational) refutation. As Perry writes above, it persists mostly because it has an “attractive simplicity,” governmental backing, and provides an advantage for some very profitable businesses.

    I’m embarrassed for the “Society for Science-Based Medicine” after reading the post you linked. The argument is essentially that, since carb-reduction has not yet been PROVEN to be the answer, we should stick with what we have — despite the fact that what we have is itself essentially based on received conventional wisdom, and NOT science. Oh, and it doesn’t work either.

    It’s a little like believing that lead paint was safe because it had always been considered safe, even as evidence mounted for roughly 100 years that it was not. In other words, we’ve done this dance of “attractive simplicity” before — many times.

    We ignore actual science at our own peril.

    • Submitted by Susan Lesch on 05/25/2014 - 10:42 am.

      Hold on II

      Things are looking up.

      Ludwig articulated the priorities of US food policy better than anybody else in the film “Fed Up”. He impressed me.

      Lustig was able to state in the film that there “is an acceptable” level of sugar consumption. He said that clearly in the movie (something I could not find in his book “Fat Chance” which, contrary to its advertising blurb, also failed to prove that a calorie is not a calorie).

      Scientists are people. I’m “admitting” nothing whatsoever about “actual” science. Have you read their books? I’ve only had time to read about half of them.

  3. Submitted by Adam Miller on 05/20/2014 - 03:08 pm.


    There’s a bit of incongruity between the second and third sentences of this article. Of course we get fat because we eat too much (perhaps also of the wrong things) and exercise too little.

    But that’s doesn’t have to be a judgment, and it certainly says nothing about will power.

    None of us have much will power, for biological and evolutionary reasons. Getting the balance of eating the right amount (and the right stuff) and exercise right takes knowledge, planning, preparation and priority-setting, not will power.

  4. Submitted by Greg Kapphahn on 05/20/2014 - 03:11 pm.

    It Won’t Be Too Long

    Before the entire “common wisdom” of weight loss, obesity, and what constitutes a life-enhancing way of living,…

    all that has caused us Americans and those who sought to copy us to become so increasingly unhealthy for the past thirty years,…

    will be swept aside in favor of two things:

    1) a far greater awareness of how the human body actually works when it comes to food consumption, exercise and health,…

    and 2) an appreciation of how the genetic differences between us cause marked differences in how we process and tolerate various foods, how well we can tolerate exercise, and what types of exercise work best for each individual.

    Unfortunately, it will take a good deal longer before we come come to understand how the ancient systems within our brains, which operate at what we might think of as the system board, or system B.I.O.S. level within us,

    systems which actually create physical changes in the brain in response to things we experience,…

    tend to create programmed patterns of thought and behavior in response to our more difficult experiences,…

    programmed behaviors which may have served our most primitive, hunter-gatherer ancestors well, but which now cause major behavioral misfires and personality dysfunctions in response to the world in which we life.

    Indeed, I can only hope that someday secondary students will be taught how to reprogram their own brains to compensate for those misfires, and generally maintain the health and well being of their own psyches rather than just their bodies.

  5. Submitted by Lance Groth on 05/20/2014 - 03:36 pm.

    Not surprising

    We did not evolve eating lots of high glycemic carbs, and not at all eating highly processed carbs. You cannot override a couple of million years of evolution with a few thousand years of agriculture, and a couple of hundred years of processed foods.

    A diet rich in high glycemic carbs, especially paired with the modern sedentary lifestyle, leads to elevated insulin levels, leads to insulin resistance syndrome, leads to obesity, leads to type 2 diabetes. It is a vicious, self-reinforcing feedback loop. This is old news, really, going back at least to Atkins some 40+ years ago. What’s new is that mainstream research is increasingly supporting this view, and that is good news.

    But yes, changing the common “wisdom” is a slow process, especially with big commercial interests working against it.

  6. Submitted by mike schoonover on 05/29/2014 - 11:53 am.

    putting the cart before the horse

    first you have to eat to much and exercise less to get overweight.
    then when your overweight its why you eat to much?
    the number one single cause of obesity is eating to much and
    exercising to little. a very small percent may have hormonal
    problems and,genetics may (notice i said may)be a factor.
    now that obesity is considered a medical condition lets milk
    this cash cow for all its worth.instead of giving out prescriptions to the gym,lets try everything else first.
    you are not overweight because you have diabetes and hormone have diabetes and hormone problems because
    your overweight.

Leave a Reply