What causes obesity? Most health professionals blame weight gain on an imbalance between calories in versus calories out. In other words, eating too much and moving too little. This concept is known as the Energy Balance Model or EBM. But a new perspective published in the American Journal of Clinical Nutrition calls that idea into question (American Journal of Clinical Nutrition, online Sept. 13, 2021).
Is Weight Gain Due to Eating Too Much or to Eating Processed Carbs?
The authors are some of the leading nutrition experts in the world, including David Ludwig, Walter Willett and Eric Westman. They recommend research to see whether the Carbohydrate-Insulin Model (CIM) fits the evidence on weight gain better.
In this paradigm, consuming highly processed, quickly digested carbohydrate kickstarts insulin production, which results in fat storage. They hypothesize that the brain then senses inadequate energy for other tissues. When it does, it triggers hunger that results in overeating. When the body uses insulin this way, hormonal changes may privilege fat accumulation over other physiological needs.
How Can We Find Out What Is Driving Obesity?
To find out for sure, scientists will have to do studies aimed at clarifying whether this model explains the evidence. This will undoubtedly be quite challenging.
The article enumerates eight testable hypotheses on weight gain. If the CIM offers the best explanation, public health authorities will need to base their policies on the evidence. That would be a shift away from blaming overweight individuals for their condition.
The carbohydrate-insulin model proposes that not all calories are equal. People might need to cut back on highly processed carbs (sugar and starch) to break the cycle.
As the authors note:
“A practical strategy is to substitute high-GL [glycemic load] foods (refined grains, potato products, concentrated sugars) with high-fat foods (e.g., nuts, seeds, avocado, olive oil), allowing for moderate intake of total carbohydrate from whole-kernel grains, whole fruits, and legumes and nonstarchy vegetables.”
Nothing should stop any of us from doing our own private experiment at reversing weight gain by reducing our intake of highly-refined foods.