By Joseph E. Scherger, MD, MPH
Core Faculty, Eisenhower Health Family Medicine, Residency Program, Eisenhower Health Center, La Quinta, CA; Clinical Professor, Keck School of Medicine, University of Southern California, Los Angeles
SYNOPSIS: Researchers posit that solving the obesity epidemic is not as simple as eating less and moving more.
SOURCE: Ludwig DS, Aronne LJ, Astrup A, et al. The carbohydrate-insulin model: A physiological perspective on the obesity pandemic. Am J Clin Nutr 2021; Sep 13:nqab270. doi: 10.1093/ajcn/nqab270. [Online ahead of print].
Carbohydrates all become sugar in the body and stimulate insulin secretion. Our ancestral diets were relatively low in carbohydrates. Further, those carbohydrates that existed in nature were unrefined and did not raise blood sugar levels quickly like today’s processed foods.
Recently, Ludwig et al argued why eating less and moving more is a failed strategy for losing weight and combatting obesity. These conditions are not a matter of energy balance or calories in vs. calories out, what might be referred to as the energy balance model (EBM). Rather, Ludwig et al traced the problem to the types and quality of food consumed through what they called the carbohydrate-insulin model (CIM).1
A key part of CIM is glycemic load (GL) and how that affects insulin. Processed grains and foods with high levels of free sugar carry a heavier GL. The authors explained how consuming a high GL diet can trigger a series of physiological events that disrupt normal bodily functions and lead to more insulin resistance, which can cause more fat deposition.
The consequences are devastating to health and results in a long list of chronic diseases. Besides excess weight and obesity, insulin resistance has been connected to fatty liver disease, hypertension, hyperlipidemia, and type 2 diabetes.2-5
To put it in simpler terms, Ludwig et al believe the focus should be more on what humans eat — the quality of the food consumed — more than how much food is consumed. CIM is theoretical, but the authors have provided a framework with hypotheses that can be tested. They called on other investigators to conduct more rigorous studies into the EBM vs. CIM, which could lead to progress on this critical public health matter.
What we eat is more important than the calories we consume. It is hard to move beyond the logic of calories in, calories out for understanding excess weight. In the end, calories do matter.
Carbohydrates drive hunger through fluctuating blood sugar levels. Those who consume processed carbs eat much more in the end. Energy-dense fats and protein foods (e.g., nuts, seeds, eggs, meat, and fish) are much more satisfying and result in less hunger and stable blood sugar levels.
As Ludwig et al and others have hypothesized, time-restricted eating (i.e., consuming meals only during an eight- to 12-hour daytime window) could be important for a healthy metabolism.6,7 I tell my patients the magic formula for a proper diet is low carbohydrate intake, adequate protein intake, healthy fats, and time-restricted eating (a window no wider than 12 hours daily).
- Ludwig DS, Ebbeling CB. The carbohydrate-insulin model of obesity: Beyond “calories in, calories out.” JAMA Intern Med 2018;178:1098-1103.
- Utzschneider KM, Kahn SE. Review: The role of insulin resistance in nonalcoholic fatty liver disease. J Clin Endocrinol Metab 2006;91:4753-4761.
- Tarray R, Saleem S, Afroze D, et al. Role of insulin resistance in essential hypertension. Cardiovascular Endocrinology 2014;3:129-133.
- Morino K, Petersen KF, Sono S, et al. Regulation of mitochondrial biogenesis by lipoprotein lipase in muscle of insulin-resistant offspring of parents with type 2 diabetes. Diabetes 2012;61:877-887.
- Veerkamp MJ, de Graaf J, Stalenhoef AF. Role of insulin resistance in familial combined hyperlipidemia. Arterioscler Thromb Vasc Biol 2005;25:1026-1031.
- Fung J. The Obesity Code: Unlocking the Secrets of Weight Loss. 2016.
- Taubes G. The Case for Keto: Rethinking Weight Control and the Science and Practice of Low-Care/High-Fat Eating. 2020.