Scientists claim that overeating is not the primary cause of obesity


Date:
September 13, 2021
Source:
American Society for Nutrition
Summary:
A perspective article challenges the 'energy balance model,' which
says weight gain occurs because individuals consume more energy
than they expend. According to the authors, 'conceptualizing
obesity as a disorder of energy balance restates a principle of
physics without considering the biological mechanisms underlying
weight gain.' The authors argue for the 'carbohydrate insulin
model,' which explains obesity as a metabolic disorder driven
by what we eat, rather than how much. *Public health messaging
exhorting people to eat less and exercise more has failed to stem
rising rates of obesity and obesity-related diseases. *The energy
balance model, which says weight gain is caused by consuming more
energy than we expend, "restates a principle of physics without
considering the biological mechanisms driving weight gain." *The
carbohydrate-insulin model makes a bold claim: overeating doesn't
cause obesity; the process of getting fat causes overeating. *The
current obesity epidemic is due, in part, to hormonal responses to
changes in food quality: in particular, high-glycemic load foods,
which fundamentally change metabolism.

*Focusing on what we eat rather than how much we eat is a better
strategy for weight management.



FULL STORY ========================================================================== Statistics from the Centers for Disease Control and Prevention (CDC)
show that obesity affects more than 40% of American adults, placing them
at higher risk for heart disease, stroke, type 2 diabetes, and certain
types of cancer. The USDA's Dietary Guidelines for Americans 2020 --
2025 further tells us that losing weight "requires adults to reduce the
number of calories they get from foods and beverages and increase the
amount expended through physical activity."

==========================================================================
This approach to weight management is based on the century-old energy
balance model which states that weight gain is caused by consuming more
energy than we expend. In today's world, surrounded by highly palatable, heavily marketed, cheap processed foods, it's easy for people to eat
more calories than they need, an imbalance that is further exacerbated
by today's sedentary lifestyles.

By this thinking, overeating, coupled with insufficient physical activity,
is driving the obesity epidemic. On the other hand, despite decades of
public health messaging exhorting people to eat less and exercise more,
rates of obesity and obesity-related diseases have steadily risen.

The authors of "The Carbohydrate-Insulin Model: A Physiological
Perspective on the Obesity Pandemic," a perspective published in
The American Journal of Clinical Nutrition, point to fundamental
flaws in the energy balance model, arguing that an alternate model,
the carbohydrate-insulin model, better explains obesity and weight
gain. Moreover, the carbohydrate-insulin model points the way to more effective, long-lasting weight management strategies.

According to lead author Dr. David Ludwig, Endocrinologist at Boston
Children's Hospital and Professor at Harvard Medical School, the
energy balance model doesn't help us understand the biological causes
of weight gain: "During a growth spurt, for instance, adolescents may
increase food intake by 1,000 calories a day. But does their overeating
cause the growth spurt or does the growth spurt cause the adolescent
to get hungry and overeat?" In contrast to the energy balance model,
the carbohydrate-insulin model makes a bold claim: overeating isn't the
main cause of obesity. Instead, the carbohydrate-insulin model lays much
of the blame for the current obesity epidemic on modern dietary patterns characterized by excessive consumption of foods with a high glycemic
load: in particular, processed, rapidly digestible carbohydrates. These
foods cause hormonal responses that fundamentally change our metabolism, driving fat storage, weight gain, and obesity.

When we eat highly processed carbohydrates, the body increases insulin secretion and suppresses glucagon secretion. This, in turn, signals fat
cells to store more calories, leaving fewer calories available to fuel
muscles and other metabolically active tissues. The brain perceives that
the body isn't getting enough energy, which, in turn, leads to feelings
of hunger. In addition, metabolism may slow down in the body's attempt
to conserve fuel.

Thus, we tend to remain hungry, even as we continue to gain excess fat.

To understand the obesity epidemic, we need to consider not only how
much we're eating, but also how the foods we eat affect our hormones and metabolism. With its assertion that all calories are alike to the body,
the energy balance model misses this critical piece of the puzzle.

While the carbohydrate-insulin model is not new -- its origins date to the early 1900s -- The American Journal of Clinical Nutrition perspective is
the most comprehensive formulation of this model to date, authored by a
team of 17 internationally recognized scientists, clinical researchers,
and public health experts. Collectively, they have summarized the growing
body of evidence in support of the carbohydrate-insulin model. Moreover,
the authors have identified a series of testable hypotheses that
distinguish the two models to guide future research.

Adoption of the carbohydrate-insulin model over the energy-balance
model has radical implications for weight management and obesity
treatment. Rather than urge people to eat less, a strategy which usually doesn't work in the long run, the carbohydrate-insulin model suggests
another path that focuses more on what we eat. According to Dr. Ludwig, "reducing consumption of the rapidly digestible carbohydrates that flooded
the food supply during the low-fat diet era lessens the underlying drive
to store body fat. As a result, people may lose weight with less hunger
and struggle." The authors acknowledge that further research is needed
to conclusively test both models and, perhaps, to generate new models
that better fit the evidence.

Toward this end, they call for constructive discourse and
"collaborations among scientists with diverse viewpoints
to test predictions in rigorous and unbiased research." ========================================================================== Story Source: Materials provided by American_Society_for_Nutrition. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. David S Ludwig, Louis J Aronne, Arne Astrup, Rafael de Cabo, Lewis C
Cantley, Mark I Friedman, Steven B Heymsfield, James D Johnson,
Janet C King, Ronald M Krauss, Daniel E Lieberman, Gary Taubes,
Jeff S Volek, Eric C Westman, Walter C Willett, William S Yancy,
Cara B Ebbeling. The carbohydrate-insulin model: a physiological
perspective on the obesity pandemic. The American Journal of
Clinical Nutrition, 2021; DOI: 10.1093/ ajcn/nqab270 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210913135729.htm

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