The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the carbohydrate-insulin model (CIM) of obesity, asserting that it better reflects knowledge on the biology of weight control as compared with what was described as the dominant energy balance model (EBM), which fails to consider biological mechanisms that promote weight gain. Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest most comprehensive formulation abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

Automated summary

This article discusses two models of obesity, the carbohydrate-insulin model and the energy balance model. The article points out that the carbohydrate-insulin model better reflects the biology of weight control, while the energy balance model does not consider the biological mechanisms that promote weight gain. The article also provides an accurate description of the energy balance model, stating that the brain is the primary organ responsible for body weight regulation.