Reviewing a Recent Article on the Cause of Obesity

A recent article from the American Journal of Clinical Nutrition is causing controversy. Within the article, a proposition was made that the long-used energy-balance model of intake may not be the full explanation of obesity. Rather, obesity is driven more by the quality of calories consumed rather than the quantity. The piece was written primarily by Dr. David Ludwig who conducts research at Boston Children’s Hospital and is a professor at Harvard. Ludwig proposed a new explanation for obesity which he calls the “Carbohydrate-Insulin Model.” This model states that foods with a high glycemic index are the drivers behind a vicious cycle of blood sugar spikes and increased hunger levels.

Ludwig argues in his journal that a low-carb, low-glycemic diet can help end the seemingly endless cycle of increased hunger levels and fat storage. When we consume less high-glycemic-index foods, we are helping our bodies by lowering the insulin-to-glucagon ratio. As many people experience insulin resistance, this occurs most often from a sensitivity to insulin that develops when we have a large blood sugar spike after a meal. Dr. Robert Lustig is a proponent of the Carbohydrate- Insulin Model as well and brings a knowledgable insight by theorizing that the hormone leptin drives energy expenditure more so than insulin. Leptin is the hormone that inhibits hunger and diminishes fat storage in our cells, mainly in more long-term regulation of our energy expenditure.

While Ludwig and Lustig bring up valuable insight backed by science, there are many people who have been angered by this explanation of obesity. They argue that obesity is based on the previously adopted ‘calories consumed vs. calories expended’ theory. In other words, it doesn’t matter what foods you consume, as long as you remain in a deficit weight loss will be a product. In response, we must consider that while this may be true in certain aspects, our metabolic health and risk of disease are very much influenced by the quality of calories we intake. Ludwig and Lustig aim to focus on the quality of carbohydrates in our long-term state of health through their Carbohydrate-Insulin Model.

Blog Written by:

Elizabeth Hoffman, Nutrition Intern Fall 2021

References:

Putka, Sophie. “Obesity Paper Has Diet Researchers Riled Up.” Medical News, MedpageToday, 12 Oct. 2021, https://www.medpagetoday.com/special-reports/exclusives/94985.