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Scientists claim that overeating is not the primary cause of obesity

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Scientists claim that overeating is not the primary cause of obesity

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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. 

Published: September 13, 2021

Source: American Society for Nutrition

In today's world, 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, together with insufficient physical activity, is driving the obesity epidemic. 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. 

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.

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 characterised 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.

We need to consider not only how much we're eating, but also how the foods we eat affect our hormones and metabolism. 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. 

Further research is needed to conclusively test both models and, perhaps, to generate new models that better fit the evidence.

 

Story Source and Journal References:

Materials provided by American Society for Nutrition. Content may be edited for style and length.

  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


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