The Obesity Epidemic and How We Got It Wrong
Abstract & Commentary
By Joseph E. Scherger, MD, MPH
Vice President, Primary Care, Eisenhower Medical Center; Clinical
Professor, Keck School of Medicine, University of Southern California,
Los Angeles
Dr. Scherger reports no financial relationships relevant to this field of study.
Synopsis: Recent evidence suggests that the ingestion of high
glycemic carbohydrates is the main problem with overweight
and obesity and intake of these products increased after the
introduction of low-fat foods.
Source: Ng M, et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: A systematic analysis for the Global Burden of Disease Study 2013. Lancet 2014; May 28.
doi: 10.1016/S0140-6736(14)60460-8. [Epub ahead of print.]
The numbers are startling. the rates of overweight and obesity have soared worldwide in the last 33 years, according to the Global Burden of Disease Study 2013, funded by the Bill and Melinda Gates Foundation in cooperation with the World Health Organization. More than half of the obese people live in 10 countries — the United States, China, India, Russia, Brazil, Mexico, Egypt, Germany, Pakistan, and Indonesia — showing that obesity is no longer tied to culture or socioeconomic status. There has been a 28% increase in overweight and obesity in adults and a 47% increase in children. This robust study looks at both gender and age with respect to rates of overweight and obesity among different countries.
COMMENTARY
Many factors converge to cause overweight and obesity. Most populations have become more sedentary with increased urbanization. More people eat away from home than previously, especially at "fast food" restaurants. Interestingly, the rise in overweight and obesity starting in the 1980s coincided with the recognition that elevated blood cholesterol is a cardiac risk factor and the development of a low-fat food industry.
Thinking that fats, especially saturated fats, are a risk factor for heart disease is logical, but is not borne out by the data.1,2 In his popular book, Grain Brain, neurologist and nutritionist David Perlmutter lays out the benefits of saturated fats, especially on the neurologic system, and describes the dangers of elevated blood sugar coming from ingesting high glycemic carbohydrates.3
Body fat, especially around the trunk, is associated with hyperlipidemia and the other components of the metabolic syndrome, raising cardiovascular risk. The foods that are most associated with increasing body fat are the high glycemic carbohydrates. Cardiologist William Davis lays out these data well in his popular book, Wheat Belly.4
The glycemic index of foods is a nutritional measure of how much the blood sugar rises in the 90-120 minutes after a food is consumed. This measure was developed in a study at the University of Toronto published in 1981.5 Pure glucose has a glycemic index of 100. Interestingly, grain-based starches have a higher glycemic index than table sugar.6 Whole grain bread has a glycemic index of 72, white bread 68, wheat cereal 67, and table sugar 59.4-6
High glycemic foods trigger rapid insulin release and ultimately the conversion and storage of body fat in persons who are not working or exercising vigorously. High glycemic carbohydrates also drive hunger as rising and falling blood sugars trigger the desire to eat. Replacing fat with carbohydrates, especially grain-based foods, has coincided with an increase in calories consumed.7
Thirty years of discouraging saturated fats and promoting whole grains has been misguided. It is not just about calories in and calories out. The hormonal responses to the calories we eat play a major role in how much we eat and what happens in our body. The problem is excess body fat, especially in the trunk. The nutritional approach to curbing overweight and obesity is to reduce the foods that contribute most to appetite and body fat, and those are the high glycemic carbohydrates, especially grain-based foods.
References
- Chowdhury R, et al. Ann Intern Med 2014;160:398-406.
- Siri-Tarino PW, et al. Am J Clin Nutr 2010;91:535-546.
- Perlmutter D. Grain Brain. New York, NY: Little, Brown and Co.; 2013.
- Davis W. Wheat Belly. New York, NY: Rodale; 2011.
- Jenkins DJ, et al. Am J Clin Nutr 1981;34:362-366.
- Juntunen KS, et al. Am J Clin Nutr 2002;75:254-262.
- Jakobsen MU, et al. Am J Clin Nutr 2010;91:1764-1768.
